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UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO 
POSGRADO EN CIENCIAS BIOLÓGICAS 
INSTITUTO DE BIOLOGÍA 
ECOLOGÍA 
 
LA ESTRUCTURA DE LOS ENSAMBLES DE ESPECIES EN 
ESPACIO Y TIEMPO 
TESIS 
QUE PARA OPTAR POR EL GRADO DE: 
DOCTOR EN CIENCIAS 
 
P R E S E N T A: 
Constantino González Salazar 
 
 
TUTOR PRINCIPAL: DR. ENRIQUE MARTÍNEZ MEYER, INSTITUTO DE BIOLOGÍA UNAM 
COMITÉ TUTOR: DR. ADOLFO NAVARRO SIGÜENZA, FACULTAD DE CIENCIAS, UNAM 
DR. VÍCTOR SÁNCHEZ CORDERO, INSTITUTO DE BIOLOGÍA UNAM 
TUTORA INVITADA: DRA. PILAR RODRÍGUEZ MORENO, POSGRADO EN CIENCIAS BIOLÓGICAS 
 
 
MÉXICO, D.F. SEPTIEMBRE 2014 
ii 
 
 
COORDINACIÓN 
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Agradecimientos 
 
 
Agradezco al Posgrado en Ciencias Biológicas de la UNAM por la oportunidad y el apoyo 
recibido para realizar mis estudios de doctorado. También quiero extender mis 
agradecimientos al Consejo Nacional de Ciencia y Tecnología (CONACyT) por la beca 
otorgada para la realización mi tesis doctoral. 
Quiero agradecer el apoyo y tiempo dedicado por parte del Dr. Enrique Martínez Meyer, y 
miembros de mi comité tutoral: Dr. Adolfo Navarro Sigüenza, Dra. Pilar Rodríguez 
Moreno y Dr. Víctor Sánchez Cordero, para mi formación personal y académica. 
 
 
ii 
 
Agradecimientos a título personal 
 
 
Quiero agradecer a Enrique Martínez Meyer, primero que nada por brindarme su amistad 
durante todos estos años y permitirme formar parte de su grupo de trabajo, donde he podido 
crecer en lo personal y lo profesional, sin duda su apoyo y excelente guía me permitieron 
culminar esta meta. 
Agradezco a los miembros de mi comité tutoral Dr. Adolfo Navarro Sigüenza, Dra. Pilar 
Rodríguez Moreno y Dr. Víctor Sanchez Cordero, quienes aportaron ideas valiosas para 
alcanzar los objetivos planteados en este proyecto. 
Al comité de candidatura por los comentarios y sugerencias en el desarrollo de esta tesis: 
Dr. Hector Arita, Dra. Ma. Del Coro Arizmendi, Dr. Joaquín Arroyo, Dr. Adolfo Navarro y 
Dr Rodrigo Medellín. 
A los miembros de mi jurado de grado, Dra. Ella Vázquez, Dr. Joaquín Arroyo, Dr. Víctor 
Sánchez Cordero, Dra. Livia León y Dr. Luis Antonio Sánchez, por sus valiosos 
comentarios y sugerencias que han permitido mejorar sustancialmente este trabajo. 
A mis amigos y compañeros del Laboratorio de Análisis Espaciales: Armando, Saúl, Edith, 
Karina, Caro, Mariana, Samara, Anny, Delia, Yaya, Miguel, Julián, Yajaira, por la 
compañía diaria y las buenas conversaciones a la hora de la comida. 
Y porque al final es mejor pasarla en familia que pasarla bien, quiero agradecer su apoyo a 
Juany, Bety, Luis, Enrique, Hortencia, Jorge, Amilcar, Jero, y de manera muy especial a 
quienes siempre están a mi lado y que seguirán aguantándome durante mucho tiempo 
Lupita y Aura. 
 
 
 
iii 
 
Índice 
Resumen....................................................................................................................... 1 
Abstract........................................................................................................................ 3 
Introducción general.................................................................................................... 5 
 
Capítulo 1 
González-Salazar, C., Martínez-Meyer E., López-Santiago, G. (en prensa) A 
Hierarchical Classification of Trophic Guilds for North American Birds and 
Mammals. Revista Mexicana de Biodiversidad.......................................................... 14 
 
Capítulo 2 
González-Salazar, C. Trophic structure of species assemblages and spatial scales: a 
case study of North American birds and mammals. Manuscrito preparado para ser 
sometido en Community Ecology................................................................................ 44 
 
Capítulo 3 
González-Salazar, C. Body size and guild structure of birds and mammals 
assemblages across spatial scales. Manuscrito preparado para ser sometido en Acta 
Oecologica.................................................................................................................. 72 
 
Discusión general......................................................................................................... 101 
 
Apéndice: Material suplementario Capítulo1 (Listado con la clasificación en 
gremios para aves y mamíferos).................................................................................. 111 
 
1 
 
 Resumen 
Determinar si las comunidades bióticas son estructuradas por procesos deterministas 
o estocásticos es un tema central en la ecología de comunidades. Varios estudios han 
identificado que los patrones de coexistencia de las especies son consistentes con la 
hipótesis de que la competencia y la diferenciación de nichos estructuran los ensambles de 
especies. Sin embargo, éstos se han centrado principalmente en la evaluación del efecto de 
las interacciones bióticas en la estructuración de ensamblajes de especies a escalas locales, 
usando sistemas con pocas especies pertenecientes a un gremio o grupo taxonómico. En 
cambio, la estructura funcional de los ensambles de especies a través de escalas espaciales 
y de una variedad de grupos focales ha sido poco estudiada. Trabajos recientes destacan la 
importancia de integrar diferentes enfoques que representan múltiples escalas espaciales y 
temporales, así como una variedad de grupos de especies, para identificar los mecanismos 
que determinan cómo se organizan las comunidades. Así, en este estudio, se examinó la 
estructura funcional de los ensambles de aves y mamíferos de América del Norte (México, 
E.U.A. y Canadá) a través de diferentes escalas espacies, para explorar la importancia 
relativa de las restricciones ambientales y bióticas sobre la coexistencia de las especies. 
Para ello, el primer paso fue establecer un sistema de clasificación en gremios tróficos para 
este conjunto de especies (Capítulo 1). Con este fin consideré 1502 especies de avesy 
mamíferos tomando en cuenta tres criterios principales: (a) tipo de alimento principal, (b) el 
sustrato donde obtienen el alimento y (3) el periodo de actividad. La clasificación que 
obtuve fue de 22 gremios de aves y 27 de mamíferos. Siguiendo esta clasificación, en el 
Capítulo 2 examiné si los ensambles de especies muestran constancia en la proporción de 
gremios considerando varias escalas espaciales (de lo regional a lo local). Los resultados de 
este capítulo muestran que la proporción de gremios fue constate a escalas locales, 
indicando que las interacciones bióticas juegan un papel importante en la estructuración de 
las comunidades a esta escala. Por el contrario, a escalas regionales se observo que la 
distribución de los gremios no fue proporcional, es decir, el número de especies por gremio 
varía entre las diferentes regiones. Lo anterior sugiere que a esta escala los filtros 
ambientales son más importantes, limitando o favoreciendo la presencia de ciertos gremios. 
Cuando evalué la organización de las especies dentro de cada gremio (Capítulo 3), la 
2 
 
distribución de los tamaños corporales de las especies no fue constante, lo cual sugiere que 
no hay evidencia de una separación morfológica significativa entre las especies que 
coexisten, y que algunas especies pueden formar grupos de tamaños similares. Sobre la 
base de los patrones observados en este estudio, concluyo que la estructura gremial de cada 
comunidad se forma por la selección del conjunto de los gremios disponibles después del 
efecto de los filtros ambientales y los procesos históricos a lo que están sujetos las especies. 
Finalmente, destaco la importancia de utilizar un enfoque de gremios ecológicos para 
describir y comprender como se estructuran los ensambles de especies. 
 
 
 
 
3 
 
Abstract 
Whether biotic communities are structured by deterministic or stochastic processes 
is a central issue in community ecology. Several studies have shown patterns of species 
segregation that are consistent with the hypothesis that competition and niche-partitioning 
structure species assemblages in animal communities. However, these have been mainly 
focused in understanding the role of biotic interactions in structuring species assemblages at 
fine scales; therefore, differences in functional structure of species assemblages across 
spatial scales remains unclear. Additionally, most studies included few species belonging a 
particular guild or taxonomic group; therefore, understanding mechanism of species 
assembly for large assemblages is much less advanced. Ecologists are increasingly aware 
that to interpret patterns in community assembly requires approaches representing multiple 
spatial and temporal scales. Consequently, methods that can provide a directed 
quantification of structural differences of communities across spatial scales will offer more 
reliable inference about community assembly compared to methods that characterize local 
community structure alone. In this study, I examined guild structure patterns of birds and 
mammals assemblages in North America (Mexico, USA, Canada) using a multi-scale 
approach to explore the relative importance of environmental and biotic filters. The first 
step to reach this objective was to establish a classification scheme for trophic guilds 
(Chapter 1). For this purpose we considered 1502 species of mainland birds and mammals. 
This classification takes into account three main criteria to identify each guild: main food 
type, foraging substrate and activity period. The resulting classification distinguishes 22 
guilds for birds and 27 for mammals. With species grouped in this manner, the proportional 
representation of these groups in samples can be used to assess the underlying causes of 
community assembly. In Chapter 2 I examined whether species assemblages show 
constancy in guild proportions at various spatial scales (regional to local). Significant 
assembly patterns based guild proportionality models suggest that biotic interactions play 
an important role in structuring local communities, and that environmental filters are more 
important at regional scales. In contrast, when I evaluated intra-guild organization (Chapter 
3) I found little evidence that structuring of guild assemblages was mediated by constant 
body-size ratios for both taxonomic groups. Rather, I found greater variance of body-size 
4 
 
ratios within guilds, suggesting that evidence for a morphological segregation of species 
within guilds was weak and some groups of species may show aggregation in sizes within 
guilds. Based on patterns observed in this study, I suggested that using ecological guilds is 
an efficient way to describe and understand the structure of species assemblages. Guild 
structure may assume that every community is formed by selection from the set of available 
guilds after they have been filtered through the local environment and subject to historical 
contingency. 
 
5 
 
Introducción general 
Ecological communities are among the most complex systems that scientists attempt to 
understand… 
—Peacor et al. 2005 
Uno de los principales objetivos en ecología es comprender y explicar la 
importancia relativa que tienen los procesos a diferentes escalas (local oregional) para 
determinar la estructura de una comunidad (Ricklefs y Schluter 1993; Samuels y Drake, 
1997; Belyea y Lancaster, 1999; Weiher y Keddy, 1999). Para comprender cómo se 
estructuran las comunidades se han planteado una variedad de modelos que proponen lo 
que se conoce como “reglas de ensamblaje”, con el propósito de entender e identificar 
patrones comunes en la composición de especies y fundamentar los mecanismos que los 
dirigen (Diamond, 1975; Fox, 1987; Fox, 1999). Estas reglas pueden ser vistas como 
restricciones para la coexistencia entre especies (Diamond, 1975; Wilson y Whittaker, 
1995; Weiher y Keddy, 1999) y representan límites para la conformación de las 
comunidades locales a partir del conjunto regional de especies. 
La teoría original sobre el ensamble de comunidades refleja la idea de que las 
especies no co-ocurren al azar sino que su coexistencia está determinada por interacciones 
inter-especificas (e.g., competencia, facilitación, mutualismo). Sin embargo, ésta puede 
redefinirse bajo un marco más general, donde la co-ocurrencia de las especies es un 
producto tanto de factores bióticos como abióticos, así como de procesos históricos como 
especiación y extinción (Pakeman et al., 2000; Adamík et al., 2003; Grönroos y Heino, 
2012), considerando que ninguno de estos procesos son mutuamente excluyentes 
(Götzenberg et al., 2011). 
La percepción de los patrones en la estructura de los ensambles es a menudo 
influenciada por el método de agregación de las especies (Weiher y Keddy, 1995; French y 
Picozzi, 2002). Por esta razón, un ensamble puede ser visto en términos taxonómicos 
(identidad de las especies) o en términos de grupos de especies delimitadas por alguna 
característica ecológica o por su parecido en la explotación de los recursos disponibles. 
6 
 
Estos conjuntos de especies diferenciados por el uso de recursos son llamados gremios o 
grupos funcionales (Root, 1967; Gitay y Noble, 1997). El estudio de estos gremios es 
importante por su aporte al conocimiento de la estructura comunitaria, y porque ayuda a 
entender los procesos asociados a su organización, permitiendo formular reglas generales 
sobre cómo se ensamblan las comunidades (Terborgh y Robinson, 1986; Wilson, 1989; 
Keddy, 1992; Bycroft et al., 1993). De igual manera, la utilización de estos gremios nos 
provee una medio eficaz de vincular la biodiversidad con los patrones ambientales, ya que 
podemos esperar que éstos respondan de manera similar ante cambios ambientales (Gitay y 
Noble, 1997; Bond y Chase, 2002; Mac Nally et al., 2008). Consecuentemente, la 
identificación y análisisde la estructura funcional en ensambles resulta un aspecto 
fundamental en la comprensión de los procesos que determinan la organización y estructura 
comunitaria, y de cómo está puede modificarse (Pianka, 1980; Kelt et al., 1999; McCay et 
al., 2004). 
 Otro aspecto importante es el estudio de la organización intra-gremial. Al enfocar 
estudios sobre las interacciones entre las especies dentro de un gremio, se pueden describrir 
los mecanismos asociados con la diversidad (o coexistencia) dentro de cada nivel trófico 
(Wilson y Wittaker, 1995). Si las interacciones competitivas entre las especies que 
conforman una comunidad se concentran dentro de los gremios, su estudio ayuda a 
entender los aspectos organizativos de las comunidades (Wiens, 1989). Así, la estructura de 
los ensambles de especies estaría determinada por la representatividad de diferentes grupos 
funcionales, mientras que la organización del número de especies dentro de un grupo 
funcional podría estar estructurada por la diversidad morfológica. El argumento básico es 
que las diferencias morfológicas entre las especies están asociadas a la selección de 
alimentos (McCloskey, 1978; Morgan, 2005; Davies et al., 2007). Es esta diferenciación en 
el uso del recurso lo que determinaría la posibilidad de coexistencia (Jones, 1997; Tokeshi, 
1999; Holt, 2001). En consecuencia, es necesario corroborar la relación entre las 
características morfológicas de las especies y la manera en que usan los recursos 
disponibles en una localidad (Dayan et al., 1989; Jones, 1997; Dayan y Simberloff, 1994; 
Gotelli y Ellison, 2002). 
7 
 
Otro factor relevante en la búsqueda de patrones en la estructura y organización de 
los ensambles de especies es la escala a la cual se realizan las observaciones, dado que la 
estructura de la comunidad puede variar en espacio, tiempo y en múltiples escalas (Ricklefs 
y Schluter, 1993; Harrison, 1993; Holt, 1996; Morris, 2005). A través del tiempo, la 
composición de especies de una comunidad cambia continuamente, con la expansión y 
contracción de las áreas de distribución geográfica, extinciones y colonizaciones. A través 
del espacio, las comunidades reflejan la influencia de una variedad de factores, como las 
diferencias de hábitat, factores históricos y restricciones geográficas (Belya and Lancaster, 
1999). Esto implica que, para comprender los patrones observados en la estructura de los 
ensambles de especies, debe incluirse información sobre factores abióticos y procesos 
históricos cuando se buscan generalizaciones ecológicas a nivel local (Roughgarden y 
Diamond, 1986; Rickleffs y Schluter, 1993; Poff y Allan, 1995). 
La identificación de los factores que determinan la coexistencia de las especies y los 
mecanismos que regulan su organización es esencial para comprender el entorno biótico 
actual y para predecir la respuesta de las comunidades a cambios ambientales o 
modificaciones en el hábitat. El objetivo general de este trabajo fue determinar si existe una 
estructura y organización funcional de los ensambles de especies a través de diversas 
escalas espaciales (locales y regionales) y si los patrones de organización son similares 
entre diferentes grupos taxonómicos, para el caso particular de las aves y mamíferos 
terrestres de Norteamérica (México, Estados Unidos y Canadá). 
Para alcanzar el objetivo planteado, la primera meta fue contar con una clasificación 
gremial para los dos grupos taxonómicos. Considerando la extensión geográfica del estudio 
y la falta de una clasificación con criterios similares para asignar cada especie dentro de un 
gremio, el objetivo principal del primer capítulo fue generar una clasificación siguiendo la 
definición original de gremio propuesta por Root (1967). Esta clasificación se basa en los 
recursos alimenticios, los hábitos de forrajeo, así como los periodos de actividad de las 
diferentes especies, permitiendo tener una clasificación gremial donde cada especie 
pertenezca únicamente a un gremio. 
8 
 
 Una vez obtenida la clasificación de las especies, en el capítulo 2 se analizó la 
estructura gremial de los ensambles de aves y mamíferos a través de varias escalas 
espaciales (local a regional), con el objetivo de identificar si la organización de las 
comunidades bióticas está determinada por filtros bióticos o abióticos. Para poder analizar 
la organización aun nivel multi-trófico se examinó la regla de proporcionalidad de gremios, 
la cual establece que la proporción de especies de cada grupo funcional tiende a permanecer 
constante para cada localidad (Wilson, 1989; Wilson, 1995; Wilson y Roxburgh, 1994). 
Para identificar el papel de los factores bióticos y abióticos en la estructura de los 
ensambles, se dividió el conjunto regional de especies en conjuntos de especies afines a 
ambientes similares, (Belmarker y Jetz, 2013). Estas áreas fueron los biomas delineados en 
le mapa de ecorefiones de la World Wildlife Fund (Olson et al., 2001). Lo anterior nos 
permite analizar los ensambles locales con la regla de proporcionalidad de gremios 
considerando únicamente las especies que pueden formar parte de una comunidad local 
después de un filtro ambiental. 
Por último, en el capítulo 3 se analizó la organización intra-gremial con base en la 
variación morfológica de las especies, con el objetivo de determinar cómo se organizan las 
especies dentro de cada gremio. Para ello se utilizó la medida de masas corporales de las 
especies, ya que es un parámetro que ha permitido describir diversos patrones de 
organización en las comunidades bióticas (Brown, 1975; Kelt y Brown, 1998; Brown y 
Nicoletto, 1991; Smith et al., 2004). Se utilizó la regla de separación constante de tamaños 
en cada gremio, donde se espera que la distribución de las especies tenga una separación 
constante de acuerdo a su tamaño, permitiendo la coexistencia de especies que utilizan 
recursos de manera similar (Bowers y Brown, 1982). Al aplicar esta regla en diferentes 
escalas se espera que a niveles regionales esta separación no sea observada y que la 
variación en tamaños corporales sea menor que la observada en nivel local. 
 
 
9 
 
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14 
 
 
 
 
 
 
 
 
 
 
CAPITULO 1 
A Hierarchical Classification of Trophic Guilds for 
North American Birds and Mammals 
 
Clasificación jerárquica de gremios tróficos para aves y mamíferos de 
Norteamérica 
 
 
 
 
 
González-Salazar, C., Martínez-Meyer E., López-Santiago, G. (en prensa) A Hierarchical 
Classification of Trophic Guilds for North American Birds and Mammals. Revista Mexicana de 
Biodiversidad. 
 
15 
 
Guilds will become the standard currency of ecologists in their efforts to understand community 
relationships of many kinds 
Terborgh& Robinson, 1986 
 
Abstract 
 The identification and analysis of ecological guilds have been fundamental to 
understand the processes that determine the structure and organization of communities. 
However, reviewing studies that have tried to categorize species into trophic guilds we 
found many different criteria on which such categorizations are based; consequently, a 
single species may have several guild designations, limiting its accuracy and applicability. 
In this paper we propose a classification scheme for trophic guilds as a first step to establish 
a common terminology. For this purpose we considered 1502 species of mainland birds and 
mammals from North America (Mexico, USA, and Canada). This classification takes into 
account three main criteria to identify each guild: mainfood type, foraging substrate and 
activity period. To determine the trophic guilds and assign species to them, we performed a 
cluster analysis to classify species according to their similarities in feeding patterns. The 
resulting hierarchical classification distinguishes six main levels of organization, which 
may occur in different combinations among taxonomic groups and sites: (1) taxon (e.g., 
birds or mammal), (2) diet (e.g., granivore, insectivore), (3) foraging habitat (e.g., 
terrestrial, arboreal), (4) substrate used for foraging (e.g., ground, foliage), (5) foraging 
behavior (e.g., gleaner, hunter), and (6) activity period (e.g., nocturnal, diurnal). We 
identified 22 guilds for birds and 27 for mammals. This approach aims to group together 
species that use similar resources in a similar way, and extend the usefulness of this 
approach to studies intend to analyze the organization of biotic communities. 
 
16 
 
Introduction 
The term “guild” was originally proposed and defined by Root (1967) as a group of species 
that exploit the same class of environmental resources in a similar way. The way Root 
applied the concept in his own work clarifies the importance he gave to functional 
relationships in a guild. For instance, Root described a “foliage-gleaning guild” containing 
five species that overlapped in their foraging maneuver, use of substrate and diets. The term 
thus groups together species, without regard to taxonomic position, that overlap 
significantly in their niche requirements. Moreover, the concept focuses attention on all 
sympatric species involved in a competitive interaction, regardless of their taxonomic 
relationship (Root, 1967; Wiens, 1989a). Consequently, we can expect that each species 
fulfills an ecological role according to its use of resources within a community (Ricklefs, 
2010). 
 Since Root (1967) proposed the term “guild”, there has been a steady rise in the use 
of the concept in three major contexts in the ecological literature (Terborgh and Robinson, 
1986; Blondel, 2003): (1) studies aiming to determine how species belonging to the same 
guild partition the resources (e.g., M’Closkey, 1978; Browers and Brown, 1982; Wiens, 
1989b); (2) studies of single communities to identify the resources that determine the 
community structure (e.g., Diamond, 1975; Landres and MacMahon, 1980; Corcuera, 
2001), and (3) comparisons of different communities in similar or contrasting environments 
(e.g., Karr, 1980; Gómez de Silva and Medellin, 2002; Mouillot et al., 2006; Adams, 2007). 
Therefore, biologists can use the guild concept to show how different taxa interrelate and 
how habitat change influences community dynamics and not just individual species. 
 However, despite the debates around the guild concept and its relevance in 
community ecology, it has been used with little attention on its theoretical basis, to the 
point that the term has been losing precision and acquiring a variety of meanings (Jaksić, 
1981; Gitay and Noble, 1997). Moreover, other terms have been proposed as a means to 
provide more precision to the concept; for instance: structural guild, referred to as a group 
of species using the same resource, but not necessarily in the same manner (Szaro, 1986); 
management guild, a group of species with similar responses to changes in their 
17 
 
environment (Verner, 1984); or functional group, defined as a group of species that respond 
similarly to environmental factors (Friedel et al., 1988). Accordingly some authors have 
used different terms more or less synonymously to “guild” and “functional group” (see 
MacMahon et al., 1981). Recently, Blonde (2003) provided a comprehensive review of the 
differences between these two concepts. 
 Some studies have proposed different types of grouping species, according to 
various concepts. On one hand, Gitay and Noble (1997) distinguished between groups 
based on resource use by species (structural guild and functional guild) and groups based 
on the response of species to environmental changes (response group and functional group). 
On the other hand, Wilson (1999) suggested applying the term “alpha guilds” to groups of 
species that used the same resource, and “beta guilds” to groups of species facing similar 
environmental conditions. Both proposals distinguish between resource used (i.e., guilds) 
and environmental conditions to assign species into a guild. The variety of terms is wide, 
and a detailed review of these concepts is beyond the scope of this work. 
 In addition to the proliferation of connotations to the term “guild”, many approaches 
have been taken to assign species to a guild, and comparisons between different studies 
have been difficult because of differences in terminology. For instance, Root (1967) 
defined the “foliage-gleaning guild,” in which Polioptila caerulea was included, but in 
subsequent works this species was classified as: “foliage and bark gleaning,” by Wagner 
(1981); “insectivore,” by Emlen (1981); “upper foliage and branch gleaner,” by De Graaf 
and Wentworth (1986); “canopy insectivore,” by Hutto (1989) and Greenberg et al. (1997); 
“twig insectivore,” by Greenberg et al. (2000); and “forest gleaner,” by Corcuera (2001). 
The lack of consensus on a common terminology results in many different ways of 
grouping species into guilds, limiting its accuracy and generalization (De Graaf et al., 1985; 
Hawkins and MacMahon, 1989; Simberloff and Dayan, 1991). 
 Most studies have binned species into guilds using food resource sharing as the sole 
criterion (e.g., herbivores, carnivores, insectivores), regardless of the way they exploit the 
resource (e.g., Cagnolo et al., 2002; Feeley, 2003; Aragón et al., 2009). A problem with 
using such coarse categories is that species overlap on the resource used; hiding the 
18 
 
ecological role they play at using similar resources in different ways. Root (1967) gave us a 
clear example when he divided insectivore birds in foliage gleaning insectivores, and 
flycatching insectivores. He considered that including the way in which species exploit 
resources was more informative about how species fulfill the niche space according to their 
ecological role. 
 Other approaches have classified species using as criteria a mix of food resources 
with other variables, such as nesting site, habitat type (e.g., Connell et al., 2000; French and 
Picozzi, 2002), morphological characteristics –e.g., quadruped, biped, flying, body size– 
(e.g., Fox and Brown, 1993; Adams, 2007) or their response to environmental conditions 
(e.g., Landres, 1983; Szaro, 1986; Croonquist and Brooks, 1991; Mac Nally et al., 2008). 
Although these classifications have proved valuable for the study of communities, they lack 
universality since are restricted to each particular study. Certainly, Root (1967) mentioned 
that it is possible to categorize species into guilds based on several types of resources. For 
example, he assigned Parus inornatus to the foliage-gleaning guild with regard to its 
foraging habits, but also it belongs to the hole-nesting guild according to its nest-site 
requirements. In any case, it is necessary to explicitly inform about the type of guild is 
being analyzed (i.e., foraging, nesting, habitat, or reproductive guild). 
 Another significant problem to obtain a uniform classification of guilds is to 
establish what criteria should be considered to classify species into guilds. Jaksić (1981) 
recognized two general approaches to characterize guilds: a priori and a posteriori. The 
first one is based on predefined guild categories and then fit species into them. The second 
approach is based on field surveys and statistical evaluation of variables describing 
foraging strategies, which reduces subjectivity. 
 Therefore, multivariate statistical techniques have been proposed to make the 
process of guild delineation more objective (e.g.,principal components analysis, cluster 
analysis, canonical correlation; Voigt et al., 2007); however, since these techniques are 
mainly based on the proportion of items, for example, the food type contained in the diet 
(Jaksić and Medel, 1990; Marti et al., 1993), they require too much information thus are 
limited to few species (Holmes and Recher, 1986; Sarrías et al., 1996; Muñoz and Ojeda, 
19 
 
1997; Rau and Jaksić, 2004; Zapata et al., 2007). Furthermore, these classifications 
consider only the shared resources and neglect the way in which species use them, an 
important aspect in guild assignment. 
 The overall result is that each study using guilds must be evaluated on its own 
merits. Beside one must be cautious when comparing guild analysis between studies 
because it frequently occurs that classifications do not match and species are designated to 
different guilds. Undoubtedly, guilds can be combined in different ways for different 
purposes; however, unified criteria are important to reach a common classification and 
terminology. 
 In this study we attempted to recover the original definition of “guild” proposed by 
Root (1967), avoiding some of the problems mentioned above (Jaksić, 1981; Hawkins and 
MacMahon, 1989; Simberloff and Dayan, 1991; Gitayand Noble, 1997; Wilson, 1999). 
Here we propose a hierarchical classification scheme for trophic guilds applied to North 
American birds and mammals using two main characteristics. First, we considered three 
main classification variables: main food item, foraging substrate and activity period. These 
three components were selected because they are the basic information available for most 
species. Second, the combination of these variables produce exclusive guilds, i.e., every 
species belongs to a single guild. These two attributes make this proposal widely applicable 
for most species of birds and mammals and allow unequivocal designations of species into 
guilds that facilitates intra- and inter-community analysis. 
Methods 
List of species: To classify birds and mammals into guilds we first obtained the list of North 
American (Mexico, USA and Canada) species, excluding those mostly associated with 
marine and coastal environments, and non-native species. The final list consisted of 1502 
species, of which 858 were birds and 644 mammals. For both groups, their taxonomy was 
reviewed and updated, eliminating problems of synonymy and taxonomic changes. For 
mammals, we followed the criteria described by Hall (1981), Ramírez-Pulido et al. (2005), 
and Wilson and Reader (2005). For birds, the corresponding authorities were the American 
20 
 
Ornithologists’ Union (AOU, 1998) and supplements 42 to 50 (AOU, 2000; Banks et al., 
2002, 2003, 2004, 2005, 2006, 2007, 2008; Chesser et al., 2009). 
Main food items: To classify species based on diet we considered the main food resource 
used by birds and mammals as follows: vertebrates (birds, mammals, reptiles, amphibians 
and fish), aquatic and terrestrial invertebrates, carrion, nectar, fruits, seeds, other plant 
material (e.g., stems, buds, leaves, etc.) and grass. Additionally, we included vertebrate 
blood as a resource for vampire bats. A key issue was how to assign the main food item to 
each species. To solve this, we took into account the food type representing the highest 
percentage in the diet of each species (when the relevant information existed), using only 
data for adult individuals and considering reproductive season for migratory birds. If 
quantitative information was not available, we considered the main food type reported in 
the literature. In cases where even this information was not available, we made a decision 
based on the information for the genus of the target species. 
Foraging substrate and technique: The foraging substrate refers to the place where 
organisms obtain their food. In this component we considered four main divisions: ground, 
air, trees, and freshwater. However, given the differences between birds and mammals, 
these categories have subdivisions exclusive to each group (Table 1). Additionally, we 
considered for each species its foraging behavior or technique used to obtain its food. This 
information indicates the way they use the resource. For birds, we considered: gleaner, 
excavator, hawker, aerial chaser, and scavenger. For mammals we considered: hunter, 
hawker, excavator, browser, grazer and scavenger. 
Activity period: Elton (1933) divided species into diurnal and nocturnal as a means to 
understand community structure, but this feature has been largely ignored for analyzing 
resource exploitation by species in guild classifications. Notable exceptions are the works 
of Schoener (1974), Marti et al. (1993) and more recently Kronfeld-Schor and Dayan 
(2003), who integrated this aspect into the analysis of community structure. In this study 
we considered two classes: (1) diurnal, if the activity period started mainly in the morning 
and continued during the day; and (2) nocturnal, when activity starts in the late hours of the 
afternoon and continues throughout the night. 
21 
 
Assigning species into a guild: Information about diet, foraging substrate and activity 
period was obtained from a review of published specialized literature and information 
available online (Electronic Supplementary Material Appendix 1).With this information in 
hand we built a binary matrix of species traits for a cluster analysis. The similarity matrix 
was obtained using the Jaccard’s Similarity Coefficient (Krebs, 1989; Mainly, 1994) and 
the dendrogram was constructed with the single linkage algorithm (Hammer et al., 2001). 
To determine the level of similarity that defines the groups in the dendrogram, we 
considered two criteria simultaneously: (1) the average similarity between all pairs of 
species (Crisci and López-Armengol, 1983), and (2) the largest increase of dissimilarity 
between successive clusters in the dendrogram (a measure of the variability of error; Hair 
1995). When both criteria were not coincident, priority was given to larger similarity 
(Gauch, 1982; Crisci and López-Armengol, 1983). 
Results 
Guild classification 
 The cluster analysis summarizes the relationships among species based on their feeding 
patterns (Electronic Supplementary MaterialAppendix 2), determining 22 bird and 27 
mammal guilds (Figs. 1 and 2, respectively). In addition, the cluster analysis also helped to 
identify particular features associated to each of these guilds. Below we provide a brief 
description of the guilds identified for birds and mammals; the full list of species with their 
associated guild is available in Table S1 and S2. 
Bird guilds 
The 22 guilds obtained for birds can be grouped into eight broader groups based on diet, as 
follows: carnivores (five guilds), frugivores (two guilds), granivores (two guilds), 
herbivores (one guild), insectivores (eight guilds), nectarivores (one guild), scavengers (one 
guild), and omnivores (two guilds). In the following paragraphs we describe each guild, 
providing examples of species belonging to them. 
1. Carnivores 
22 
 
 Air-hawker: species that specialize in hunting prey in the air; their main food item is 
other birds and bats. Representative species of this guild are falcons, e.g., Falco 
columbarius (merlin), F. peregrinus (peregrine falcon); 
 Arboreal-hawker: represented by some eagles specialize in hunting prey in the 
canopy, such as monkeys, reptiles or birds; for example, Harpia harpyja (harpy eagle) and 
Geranospiza caerulescens (crane hawk); 
 Ground-hawker: includes birds of prey that feed on a wide variety of vertebrates 
(birds, mammals, reptiles) that they catch on the ground, e.g., Buteo jamaicensis (red-tailed 
hawk), Circus cyaneus (northern harrier); 
 Nocturnal: species active mainly at night; including mostly owls that hunt several 
species of vertebrates, e.g.,Bubo virginianus (great horned owl); 
 Freshwater-forager: species that feed mainly on fish and a large number of aquatic 
invertebrates caught in rivers or lakes, e.g., Pandion haliaetus (osprey), Megaceryle 
torquata (ringed kingfisher), Cinclus mexicanus (American dipper). 
2. Frugivores 
 Ground to lower canopy gleaner: species that forage on the ground andin the lower 
parts of trees or shrubs, e.g., Tinamus major (great tinamou), Crax rubra (great curassow); 
 Upper-canopy gleaner: birds foraging on fruits mainly in the upper parts of trees, 
e.g., Ortalis vetula (plain chachalaca), Aratinga holochlora (green parakeet). 
3. Granivores 
 Ground to undergrowth gleaner: these birds glean seeds principally on the ground 
and shrubs and rarely forage in trees, e.g., Callipepla squamata (scaled quail), Junco 
hyemalis (dark-eyed junco); 
 Lower to upper canopy gleaner: these species get their food on any of the tree 
strata, e.g., Loxia curvirostra (red crossbill), Acanthis flammea (common redpoll). 
23 
 
4. Herbivores 
 Ground forager: represented mainly by species distributed in northern United States 
and Canada. These birds eat different parts of plants mostly on the ground, e.g., Lagopus 
lagopus (willow ptarmigan), Dendragapus obscurus (dusky grouse). 
5. Insectivores 
 Air hawker above canopy: species feeding mainly on insects caught in the air above 
the tree canopy, e.g., Cypseloides storeri (white-fronted swift), Elanoides forficatus 
(swallow-tailed kite), Ptiliogonys cinereus (gray silky-flycatcher); 
 Air hawker under canopy: birds feeding mainly on insects caught in the air mostly 
under the canopy, e.g., Elaenia martinica (Caribbean elaenia), Momotus momota (blue-
crowned motmot), Contopus pertinax (greater pewee); 
 Bark excavator: species that feeds on insects caught on the internal side of tree bark, 
e.g., Melanerpes chrysogenys (golden-cheeked woodpecker), Picoides scalaris (ladder-
backed woodpecker), P. villosus (hairy woodpecker); 
 Bark gleaner: these species feed on insects caught on the surface of barks, e.g., 
Sittasomus griseicapillus (olivaceous woodcreeper), Sitta canadensis (red-breasted 
nuthatch), Mniotilta varia (black-and-white warbler); 
 Ground gleaner: includes species that feed primarily on insects caught on the 
ground, e.g., Campylorhynchus brunneicapillus (cactus wren), Turdus migratorius 
(American robin); 
 Lower canopy foliage gleaner: species that feed on insects caught on the foliage, 
foraging from the lower to middle parts of trees, e.g., Thamnophilus doliatus (barred 
antshrike), Piaya cayana (squirrel cuckoo), Vireo huttoni (Hutton's vireo); 
 Upper canopy foliage gleaner: Includes species that feed on insects caught on the 
foliage, foraging from the middle to high parts of trees, e.g., Leptodon cayanensis (gray-
24 
 
headed kite), Coccyzus americanus (yellow-billed cuckoo), Piranga ludoviciana (western 
tanager); 
 Nocturnal: species feeding on insects at night, e.g., Megascops cooperi (pacific 
screech-owl), Chordeiles acutipennis (lesser nighthawk), Nyctibius jamaicensis (northern 
potoo). 
6. Nectarivores 
 Nectarivore: species which main food item is nectar from flowers, e.g., 
Campylopterus curvipennis (wedge-tailed sabrewing), Amazilia candida (white-bellied 
emerald), Lampornis amethystinus (amethyst-throated hummingbird). 
7. Scavengers 
 Scavenger: species that feed on carrion, e.g., Coragyps atratus (black vulture), 
Cathartes burrovianus (lesser yellow-headed vulture). 
8. Omnivores 
This group included species that cannot be differentiated by any type of food, yet they can 
be distinguished by their foraging habits. 
 Arboreal forager: species that feed on a wide variety of foods (insects, vertebrates, 
seeds, fruits, parts of plants) obtained from the canopy of trees, e.g., Cyanocorax morio 
(brown jay), Cacicus melanicterus (yellow-winged cacique); 
 Ground forager: includes species that forage on several types of food, including 
carrion, mainly on the ground, e.g., Corvus corax (common raven), Pica hudsonia (black-
billed magpie), Quiscalus mexicanus (great-tailed grackle). 
Mammal guilds 
For mammals, we obtained 27 guilds grouped into eight feeding groups, namely carnivores 
(three guilds), frugivores (three guilds), granivores (four guilds), herbivores (seven guilds), 
25 
 
insectivores (six guilds), nectarivores (one guild), sanguinivores (one guild), and omnivores 
(two guilds). 
1. Carnivores 
 Ground hunter-diurnal: mammals feeding mainly on vertebrates hunted on the 
ground during the day, e.g., Puma yagouaroundi (jaguarundi), Mustela frenata (long-tailed 
weasel); 
 Ground hunter-nocturnal: species that hunt on the ground at night, e.g., Lynx rufus 
(bobcat), Panthera onca (jaguar), Gulo gulo (wolverine); 
 Freshwater forager: mammals that feed mainly on aquatic vertebrates in rivers or 
lakes, e.g., Noctilio leporinus (greater bulldog bat), but can also eat aquatic invertebrates, 
e.g., Lontra canadensis (North American river otter), Rheomys mexicanus (Mexican water 
mouse). 
2. Frugivores 
 Arboreal forager-diurnal: includes mammals that eat fruits collected on trees during 
the day, e.g., Alouatta pigra (Mexican black howler monkey), Sciurus deppei (Deppe's 
squirrel); 
 Arboreal forager-nocturnal: includes mammals that eat fruits collected on trees 
during the night, e.g., Artibeus jamaicensis (Jamaican fruit-eating bat), Potos flavus 
(kinkajou); 
 Ground forager-diurnal: mammals which primary food is fruit collected on the 
ground, e.g., Dasyprocta mexicana (Mexican agouti). 
3. Granivores 
 Arboreal forager-diurnal: species that eat seeds and forage primarily in the canopy 
during the day, e.g., Sciurus griseus (western gray squirrel), Tamiasciurus mearnsi 
(Mearns's squirrel); 
26 
 
 Arboreal forager-nocturnal: species that eat seeds in the canopy at night, e.g., 
Glaucomys sabrinus (northern flying squirrel), Ochrotomys nuttalli (golden mouse); 
 Ground forager-diurnal: includes animals that feed mainly on seeds collected on the 
ground, e.g., Tamias merriami (Merriam's chipmunk), Ammospermophilus harrisii 
(Harris's antelope squirrel); 
 Ground forager-nocturnal: mammals that forage seeds on the ground mostly at 
night, e.g., Dipodomys merriami (Merriam's kangaroo rat), Peromyscus maniculatus (deer 
mouse), Zapus trinotatus (Pacific jumping mouse). 
4. Herbivores 
 Arboreal forager-diurnal: mammals that feed on several plant parts, including fruit, 
seeds, and leaves, mainly in the canopy and during the day, e.g., Sciurus arizonensis 
(Arizona gray squirrel), Sciurus colliaei (Collie's squirrel); 
 Arboreal forager-nocturnal: mammals that feed in the canopy on a large variety of 
plant parts, including fruit, seeds, leaves; mainly at night, e.g., Arborimus pomo (Sonoma 
tree vole), Tylomys bullaris (Chiapan climbing rat); 
 Fossorial: mammals adapted to live and carry out most of their activities (eating, 
resting and reproducing) underground, feeding mainly on stems, roots and bulbs, e.g., 
Geomys arenarius (desert pocket gopher), Thomomys mazama (western pocket gopher); 
 Ground forager-diurnal: mammals that feed on a great variety of plant parts mainly 
on the ground, foraging mainly during the day, e.g., Tayassu pecari (white-lipped peccary), 
Cynomys mexicanus (Mexican prairie dog); 
 Ground forager-nocturnal: mammals that feed on a great variety of plant parts 
mainly on the ground and foraging mainly at night, e.g., Lepus californicus (black-tailed 
jackrabbit), Cuniculus paca (lowland paca); 
 Freshwater forager: mammals that feed mainly on aquatic vegetation, e.g., Ondatra 
zibethicus (muskrat), Castor canadensis (American beaver); 
27 
 
 Grazers: species that eat mainly on grass and leaves, e.g., Bison bison (American 
bison), Odocoileus virginianus (white-tailed deer). 
5. Insectivores 
 Aerial hawker-nocturnal: includes bat species that feed mainly on insectscaught in 
the air at night, e.g., Balantiopteryx plicata (gray sac-winged bat), Pteronotus personatus 
(Wagner's mustached bat), Myotis albescens (silver-tipped myotis); 
 Arboreal forager: includes species that feed mainly on insects in the trees, e.g., 
Cyclopes didactylus (silky anteater), Marmosa mexicana (Mexican mouse opossum); 
 Fossorial: species of fossorial habits that feed mainly on insects caught 
underground, e.g., Scapanus latimanus (broad-footed mole), Blarina carolinensis (southern 
short-tailed shrew); 
 Ground forager-diurnal: mammals that feed on insects caught on the ground, during 
the day, e.g., Cryptotis nelsoni (Nelson's small-eared shrew), Sorex arizonae (Arizona 
shrew), Sorex ventralis (chestnut-bellied shrew); 
 Ground forager-nocturnal: mammals that feed on insects caught on the ground at 
night, e.g., Spilogale pygmaea (pygmy spotted skunk), Onychomys leucogaster (northern 
grasshopper mouse); 
 Forager-nocturnal: bats feeding primarily on insects, but that rarely catch their 
prey on the fly; however, they do not have preference for any type of substrate to forage, so 
they can get their food on the ground or in trees; e.g., Mimon crenulatum (striped hairy-
nosed bat), Tonatia saurophila (stripe-headed round-eared bat). 
6. Nectarivores 
 Nectarivore-nocturnal: bat species that feed primarily on nectar, e.g., Glossophaga 
leachii (gray long-tongued bat), Leptonycteris curasoae (southern long-nosed bat). 
7. Sanguinivores 
28 
 
 Sanguinivore: represented by only three species of bats that feed on vertebrate 
blood, e.g., Diaemus youngi (white-winged vampire bat). 
8. Omnivores 
Like birds, these are mammals that cannot be distinguished by their type of food or 
foraging substrate yet can be classified by their activity period. 
 Omnivore-diurnal: mammals that eat a wide variety of food items. They get their 
food from different substrates, mainly during the day, e.g., Nasua narica (white-nosed 
coati), Martes americana (American marten). 
 Omnivore-nocturnal: mammals that eat a wide variety of food. They get their food 
from different substrates, mainly at night, e.g., Canis latrans (coyote), Bassariscus astutus 
(ringtail). 
Discussion 
 Since Root (1967) proposed the guild concept, a number of authors have discussed 
guild terminology, definitions and its applications in ecological studies (see Jaksić, 1981; 
Terborgh and Robinson, 1986; Hawkins and MacMahon, 1989; Wiens 1989a; Simberloff 
and Dayan, 1991). Consequently, new terms of guilds have been suggested (e.g., Gitay and 
Noble, 1997; Wilson, 1999), and many approaches have been undertaken to assign species 
to a guild (e.g., Jaksić and Medel, 1990; Leso and Kropil, 2007). Because of this, very few 
studies have sought to establish the firm basis for a common terminology in ecological 
guilds (e.g., De Graaf et al., 1985). 
 Considering the lack of a unified classification for ecological guilds, we reviewed 
the available information about guild classifications for birds and mammals, and found two 
contrasting situations for these groups. Root’s guild concept has been used in a large 
number of studies of birds, and they may involve a great number of species and several 
guilds (e.g., Cody, 1983; Case et al., 1983; Pearman, 2002; Adamík et al., 2003; Korňan et 
al., 2013), but only one work has attempted to provide a guild classification for a great 
29 
 
number of North American birds (De Graaf et al., 1985); yet, they used different 
terminologies, making it of little use for comparisons. For mammals, most studies 
regarding guild classifications were focused only on a few species within particular feeding 
guilds, such as granivores or insectivores, or a few species belonging to a taxonomic group, 
such as Rodentia or Carnivora (e.g., Fox and Brown, 1993; Zapata et al., 2007; Aragón et 
al., 2009). Also in some cases, morphological traits were used to classify guilds –e.g., 
quadruped, biped, flying, body size– (e.g., Fox and Brown, 1993; Adams, 2007). 
 Although, these classifications have provided valuable results in the study of 
communities, these do not strictly follow the original concept of guild (Root, 1967), and are 
restricted to specific studies. Moreover, until now, there is not a study that has attempted to 
provide a guild classification for mammals in the sense established by Root (1967). It is 
possible that the fundamental reason for this lack of agreement in the use of a common 
framework and terminology is that the guild concept is a theoretical construct rather than a 
natural unity in life. Therefore, instead of “discovering” a hidden entity, we are attempting 
to understand the way nature self-organizes in a complex, multidimensional and multiscalar 
setting. 
 Hence, given the multiplicity of approaches to assign guild membership and the lack 
of a unified terminology, we proposed a classification scheme for North American birds 
and mammals. Towards this end, we identified a variety of exclusive trophic guilds for 
mainland birds and mammals that show a clear, unequivocal separation among them 
regarding the use of available food resources.This classification is hierarchical and 
distinguishes six main levels of organization: (1) taxon (e.g., birds or mammal), (2) diet 
(e.g., granivore, insectivore), (3) foraging habitat (e.g., terrestrial, arboreal), (4) substrate 
used for foraging (e.g., ground, foliage), (5) foraging behavior (e.g., gleaner, hunter), and 
(6) activity period (e.g., nocturnal, diurnal). Certainly, this hierarchical classification would 
vary between birds and mammals, and not always the six levels are represented in guilds. 
However, our classification allows subdividing biotic communities in different levels and 
identifying ecological roles played by numerous species. Interestingly, in our classification 
bird guilds were subdivided mainly by the arboreal stratum, whereas mammal guilds were 
30 
 
divided principally by activity period, indicating different mechanism of organization 
between these taxonomic groups. 
 Undoubtedly, our proposal does not escape to issues inherent in building a 
classification of guilds (a priori vs. a posteriori approach and the concept used). Our 
classification of guilds follows the concept proposed by Root (1967) and we used a 
posteriori classification (sensu Jaksić, 1981), to make it applicable in other regions or other 
taxonomic groups. Variables used to assign species to guilds may be controversial, such as 
activity period; however, recent studies have highlighted the importance of temporal 
separation to promote species coexistence (e.g., Castro-Arellano and Lacher, 2009; Di 
Bitetti et al., 2009; Stuble et al., 2013). Some shortcomings that we have identified in our 
proposal include the fact that for birds we only considered the breeding season 
characteristics, and for mammals the gross feeding items to assign species into a guild, thus 
seasonal variations in feeding habits were not taken into account. As well, geographic 
variations in feeding habits were dismissed. Finally, we used only three qualitative 
variables for the classification. Certainly, the use of a larger set of variables, including 
quantitative ones (e.g., proportion of food items) would strengthen the statistical analyses; 
however, this information is lacking for a large proportion of species, thus including them 
in a classification would produce an incomplete scheme, reducing its applicability. 
 Another important aspect of Root’s definition is that guild classification should be 
independent of taxonomic relationship. In this regard, Jaksić (1981) suggested that a guild 
should include all kind of species that exploit the same resource (birds, mammals, reptiles 
or insects); he referred to these groups as community guild; otherwise, he defined 
assemblage guilds when the recognition of guilds were defined within taxonomicassemblages. He mentioned that restrict guild membership by arbitrary taxonomic 
boundaries may lead to a neglected of important influences among distantly related taxa. 
Even though, our classification may be considered an assemblage guild under these terms 
because guilds were built independently for birds and mammals, some of them may be 
considered as equivalent. For instance, carnivore birds and mammals that take their food on 
the ground can be considered one guild. Thus, quoting Jaksić (1981) …It seems, then, that 
31 
 
the study of guild structure within taxonomic assemblages is only a preliminary step for 
understanding the role of guilds in the organization of communities. 
 Community studies focused on guild composition bring greater clarity about 
assembly processes in contrast to studies focused on species composition. These may 
provide a more fruitful avenue for developing and testing general ecological hypotheses of 
community organization across biogeographic scales and processes of environmental 
change (e.g., Kissling et al., 2011). This standardization may provide means by which 
ecological studies can give us more robust information about relationships among species 
and their environment, and a better understand how species that form a guild might respond 
to environmental changes (Keddy, 1992; Mateos et al., 2011). For instance, analysis based 
on individual species may help to elucidate distribution patterns, whereas analyses using 
ecological groups (such as guilds) may identify assemblages according to habitat 
characteristics (Hoeinghaus et al., 2007). Sekercioglu et al., (2004) proposed a framework 
to characterize potential ecological consequences of avian declines using functional roles of 
birds and a stochastic model. This kind of studies provides a different perspective of the 
effects of environmental change on species and biotic communities. 
 Briefly, the misuse and abuse of the guild concept has driven to ad hoc 
interpretations and applications, where the usefulness of the concept depends more on the 
acuity of researchers (Jaksić, 1981; MacMahon et al. 1981; Hawkins and MacMahon, 
1989). Certainly, it will be difficult to achieve a universally accepted classification for 
guilds; however, we believe that is possible to find a standardized nomenclature to identify 
ecological groups (Dale, 2001; Korňan and Adamík, 2007; Leso and Kropil, 2007; Blaum 
et al., 2011). We hope that this study serve as a first step towards finding such common 
terminology for ecological guilds. 
 
 
 
32 
 
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