Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73 (S2): e64548, mayo 2025 (Publicado May. 15, 2025)

Differences in foraging strategies and morphology of

five warbler species (Parulidae) in a tropical mangrove forest

Gilbert Barrantes*1,2; https://orcid.org/0000-0001-8402-1930

Ana Catalina Sánchez-Quirós1; https://orcid.org/0000-0002-8714-4327

Luis Sandoval1, 2, 3; https://orcid.org/0000-0002-0793-6747

1. Escuela de Biología, Universidad de Costa Rica, San José, Costa Rica; gilbert.barrantes@gmail.com (*Correspondence);

catasq@gmail.com

2. Centro de Investigaciones en Biodiversidad y Ecología Tropical, Universidad de Costa Rica, San José, Costa Rica.

3. Laboratorio de Ecología Urbana y Comunicación Animal, Escuela de Biología, Universidad de Costa Rica, San José,

Costa Rica; biosandoval@gmail.com

Received 02-IX-2024. Corrected 13-I-2025. Accepted 04-III-2025.

ABSTRACT

Introduction: Understanding the factors underlying the interactions among closely related species continue to be

an important issue in ecology and evolution. Warblers have been the group model for studying niche partitioning

through interspecific competition, without considering other possible factors. A more recent approach includes

species-specific morphologies as an important factor that correlates with habitat (or niche) partitioning.

Objective: to compare the foraging strategies of five warbler species (Setophaga p. erithachorides, S. petechia,

Protonotaria citrea, Parkesia noveboracensis, and Leiothlypis peregrina) in a mangrove forest, and to compare

the foraging strategies of S. p. erithachorides, the only resident warbler, between periods (presence vs. absence of

migrants).

Methods: We collected information on substrates and maneuvers used during foraging for the five warbler spe-

cies during 39 sampling sessions. Each session consisted of recording information for 9 successive days every

two weeks.

Results: P. noveboracensis differed extensively from the other species in the foraging substrates and maneuvers.

The other species formed a more compact group, but some differences in both, substrates and maneuvers, were

detected between S. p. erithachorides and L. peregrina. Differences in forging strategies correlate with differences

in the morphology among the five warbles species. The foraging strategy of S. p. erithachorides differed between

periods. This warbler used the substrates similarly in both periods, but used other maneuvers or change their

frequency when migrants are present.

Conclusion: differences in the foraging strategy of five warblers can be attributed to a process of morphological

and behavioral adaptation to an adaptive scape that includes differences in microhabitat, and biotic interactions

(e.g., predation, prey availability) rather than exclusively to interspecific competition.

Keywords: substrate use; capture maneuvers; warbler morphology; Mangrove warbler; wintering warblers.

RESUMEN

Diferencias en las estrategias de alimentación y morfología de cinco especies de reinitas

(Parulidae) en un bosque de manglares tropicales

Introducción: La comprensión de los factores que subyacen a las interacciones entre especies estrechamente

relacionadas sigue siendo un tema importante en ecología y evolución. Las aves de la familia Parulidae han sido

https://doi.org/10.15517/rev.biol.trop..v73iS2.64548

SUPPLEMENT

SECTION: ECOLOGY

2Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73 (S1): e64548, mayo 2025 (Publicado May. 15, 2025)

INTRODUCTION

Ecological-interactions studies among

closely related species, particularly within a

particular habitat, have a long history in ecology

(MacArthur, 1958; Miller, 1967; Pianka, 1994).

This has been a central issue to understand

habitat partitioning and competition among

species, species-specific adaptive responses,

and the importance of such interactions in

shaping the evolution within a particular group

of species (MacArthur, 1972; Ricklefs & Miles,

1994; Winkler & Leisler, 1985). For decades,

interaction among closely related species spun

around competition and niche partitioning. A

large number of investigations have focused

on measuring differences among species and

attributing such differences to competition,

without certainly tested if competition was

the source of the differences detected, and

much less, the effect of competition on spe-

cies reproduction (Strong, 1984). Competition

cannot be completely discarded as a potential

factor influencing the coexistence of related

species in a community, since in some groups

of species competition has been important in

shaping the structure of communities (Tilman,

1987; Tilman, 1994). However, in other cases

careful conducted experiments demonstrated

that competition was inexistent, in groups of

species for which competition had previously

been considered an important ecological fac-

tor shaping the communities (Wiens, 1989;

Wise, 1993).

A more recent approach integrates mor-

phology and ecology (competition included as

a potential but not an exclusive factor) under

an evolutionary framework to understand the

habitat partitioning and foraging strategies of a

group of closely related species (Losos, 1990a;

Losos, 1990b; Losos 1990c; Losos & Miles,

1994; Norberg, 1994). This approach opened

the opportunity to consider habitat (and niche)

partitioning as an adaptive response of [indi-

viduals within species] species to variation in

the environment, considering environment as

the interaction between abiotic (e.g., vegeta-

tion structure, ambient temperature) and biotic

factors (e.g., resource availability, predation).

Within birds, new world warbles (Parulidae)

are a group model that has been the focus of

el grupo modelo para estudiar la partición de nichos por medio de competencia interespecífica, sin considerar

otros posibles factores. Un enfoque más reciente incluye las morfologías específicas de las especies como un factor

importante que se correlaciona con la partición del hábitat (o nicho).

Objetivo: comparar las estrategias de alimentación de cinco especies de reinitas (Setophaga p. erithachorides, S.

petechia, Protonotaria citrea, Parkesia noveboracensis y Leiothlypis peregrina) en un bosque de manglares, y com-

parar las estrategias de alimentación de S. p. erithachorides, la única reinita residente, entre períodos (presencia

vs. ausencia de migrantes).

Métodos: Recopilamos información sobre sustratos y maniobras utilizadas durante la alimentación de las cinco

especies de reinitas durante 39 sesiones de muestreo. Cada sesión consistió en registrar información durante 9

días sucesivos cada dos semanas.

Resultados: P. noveboracensis difirió ampliamente de las otras especies en los sustratos y maniobras de alimen-

tación. Las otras especies formaron un grupo más compacto, pero se detectaron algunas diferencias tanto en

los sustratos como en las maniobras entre S. p. erithachorides y L. peregrina. Las diferencias en las estrategias de

alimentación se correlacionan con las diferencias en la morfología entre las cinco especies de reinitas. La estrategia

de alimentación de S. p. erithachorides difirió entre períodos. Esta reinita utilizó los sustratos de manera similar en

ambos períodos, pero utilizó otras maniobras o cambió su frecuencia cuando hay migrantes presentes.

Conclusión: las diferencias en la estrategia de alimentación de las cinco reinitas se pueden atribuir a un proceso

de adaptación morfológica y conductual a un entorno adaptativo que incluye diferencias en el microhábitat y

las interacciones bióticas (por ejemplo, depredación, disponibilidad de presas) en lugar de exclusivamente a la

competencia interespecífica.

Palabras clave: uso de substrato; maniobras de captura; morfología de reinitas; reinita de manglar; reinitas

invernantes.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73 (S2): e64548, mayo 2025 (Publicado May. 15, 2025)

attention in competition and niche partitioning

(MacArthur, 1958), and on their interaction

with their tropical counterparts during the win-

tering season (Keast, 1980).

The mangrove warbler (Setophaga pete-

chia erithachorides) is the only warbler pres-

ent during the non-wintering season of North

America migratory birds in Costa Rican man-

groves (Barrantes, 1998). However, during the

overwintering period, the mangrove warbler

shared its habitat with large numbers of other

warblers, including the yellow warbler (S. pete-

chia). Yellow warblers consist of a large group

of subspecies, including the mangrove warbler

(Lowther et al., 1999). This particular condition

permits the comparison of foraging strategies

in a group of related birds inside of a relatively

simple tropical forest, the mangrove forest.

Additionally, the arriving of migratory warblers

permits contrasting the foraging strategies of

the mangrove warbler, and thus its flexibility

(plasticity), between two very different condi-

tions: being the only warbler in its habitat,

and sharing the habitat with a large number of

other family members. We specifically focus on

answering the following questions: (1) Do the

foraging strategies differ among five warbler

species (Setophaga p. erithachorides, S. petechia,

Protonotaria citrea, Parkesia noveboracensis,

and Leiothlypis peregrina) in the mangrove

forest? We particularly focus on two aspects

of foraging strategies: the substrates use by

warblers while foraging, and the maneuvers

they use to attempting capturing prey. In this

case we predict that those species more similar

in morphology shared similar foraging strate-

gies. (2) Do the mangrove warblers modify its

foraging strategy when migratory warblers are

present? We expect that if migratory warblers

with similar foraging strategies are abundant,

the mangrove warbler will modify its forag-

ing strategy. A plastic response that allows

mangrove warblers to reduce competition with

other family members.

MATERIAL AND METHODS

Description of the study area: We con-

ducted this research from July 1986 to Decem-

ber 1987 in a mangrove forest in Chomes,

Puntarenas, Costa Rica (10°, 02’ N; 84°, 54’

W). We delimited an area of 70 ha in which

all data were collected. Climatically, the region

is characterized by a long dry season, from

December to May or June, with the rainy sea-

son that includes the other months (Epifanio

et al., 1983).

The vegetation in the area vary according

to the tides influence. The zone of greater influ-

ence includes trees of Rhizophora mangle, R.

harrisonii, Avicennia germinans, A. bicolor, and

Laguncularia racemosa (Jiménez & Soto, 1985),

but in areas above the tides influence (or nearly

so) plants such as Volkameria pittieri, Conocar-

pus erectus, Prosopis juliflora, Pithecellobium

dulce, Capparis odoratissima and Cynophalla

flexuosa are common.

Substrates and foraging maneuvers: To

record the use that different warbler species

made of the mangrove forest we defined six for-

aging substrates (Supplementary Table 1). The

categorization of substrates was based on pre-

liminary observations of warblers in the study

area. To evaluate if each warbler species used

a different set of maneuvers to capture prey, we

defined 15 different maneuvers (Supplemen-

tary Table 1) based on preliminary observations

of warblers in the study area and published

information by Holmes et al. (1979); Fitzpatrick

(1980); and Robinson & Holmes (1982). These

maneuvers were defined as a combination of

specific maneuvers on a particular substrate

(Supplementary Table 1), following Fitzpatrick

(1980), Holmes et al. (1979), and Remsen &

Robinson (1990).

Collected and preparation of data: To

compare the foraging pattern of each warbler

4Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73 (S1): e64548, mayo 2025 (Publicado May. 15, 2025)

species we collected data along transects hap-

hazardly selected in the interior and border of

the mangrove. All observations were collected

from 630 to 1 200 h for 9 days every two weeks

for a total of 39 sampling sessions. Prior to col-

lect the information we created a unique letter

code for substrates (e.g., a = trunk, e = foliage)

and a unique numeric code for the maneuvers

(e.g., 1 = gleaning, 2 = probing).

We used a voice recorder (Sony M-570V

Handheld Cassette Voice) to collect the for-

aging activity of warblers. When a warbler

was found foraging, we described to the voice

recorder the sequence of different substrates

and different maneuvers that the warbler used

during the observation time. For instance, a

sequence of a1-e2-a2 means that during the

observation time the bird glean on a trunk,

then probe in the foliage, and finally probe in a

trunk. We then played back the tape to extract

the time that each individual bird spent on each

substrate and used each specific maneuver. For

each individual we summed the effective time

for each substrate and maneuver. We also had

a code to indicate that the bird was inactive.

This allowed us to subtract this time from the

total time recorded for a specific individual and

obtain the effective time.

For each individual of each species for

which we obtained a foraging sequence, we

calculated the weighted mean to compensate

for differences in the total time we observed

each individual. For example, if T1 was the total

effective time of the sequence of bird 1, Si the

time the bird foraged in the substrate i, and ΣT

the sum of the effective time of all birds of the

same species in a particular sampling session,

we calculated the weighted mean as: Si*T1/

ΣT. We next sum the weighted means of all

individuals of each species for each particular

sampling session to have an entrance (row) for

species for sampling session. This approach has

two advantages; first, it compensates for differ-

ences in the effective time across individuals,

making the data comparable across species;

and second, we reduced the effect of pseudo-

replicates, because it was likely that we recorded

some of the same individuals in consecutive

days in a sampling session. We used the same

approach for the time warbles spent in each of

the capturing maneuvers.

Morphological data: We obtained mea-

surements of seven morphological traits 1)

tarsus length [from the intertarsal joint to the

middle of the sole of the foot], 2) wing chord

length [unflattened], 3) tail length, 4) culmen

length, 5) culmen width, 6) culmen depth, and

7) weight, from specimens of the same warbler

species, from the ornithology collection of

Museo de Zoología, CIBET, Universidad de

Costa Rica. We performed a Principal Compo-

nent Analysis on morphological traits to reduce

the number of variables. The first component

explained 81% of the variance corresponding

to the seven morphological traits. Therefore,

we used the first PCA as a proxy of the birds’

morphology for comparisons.

Statistical analyses: We used two differ-

ent approaches to compare the use of sub-

strates and capturing maneuvers across species.

First, we compared the variation in time birds

spent foraging in each substrate and using each

capturing maneuver across species with the

coefficient of variation (cv). Lower cv values

indicate that birds used substrates or maneu-

vers more homogeneously.

Second, analyses of habitat use and for-

aging behavior include, in most cases, mul-

tiple variables, making univariate statistical

analyses unpractical. Considering the type of

data obtained in this study, we took a differ-

ent approach. We used statistics designed for

comparing species composition across com-

munities, but instead of species abundances we

fed the models with frequencies, specifically

with the time (number of seconds) an indi-

vidual of a given warbler species forage on

each specific substrate or spend in each of the

foraging maneuvers.

We constructed two matrices, one for sub-

strates and another for maneuvers. The col-

umns of these matrices consisted of either

the substrates or the maneuvers, and the rows

included several entries of each species. Each

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73 (S2): e64548, mayo 2025 (Publicado May. 15, 2025)

row including the number of seconds birds of

a given species forage on each specific substrate

or spend on each specific maneuver during

each sampling session (see above).

To test for differences in substrates and

maneuvers across species and for Setophaga

p. erithachorides between seasons (presence

vs. absence of migrants), we used the permu-

tational analysis of variance (PEMANOVA)

(vegan::adonis2; Oksanen et al., 2020). We test-

ed for homogeneity of multivariate variances,

using the vegan::betadisper function to test for

equal dispersion in the data, and found homo-

geneous variances (P values ranged from 0.16

to 0.68) in all cases.

The morphology was compared among

warbler species with a linear model. We includ-

ed the PCA scores corresponding to the first

component as the response variable and the

species as the predictor. We then compared

between species the PC1 means with the

functions emmeans and pairs of the package

emmeans (Lenth et al., 2018). We used the R

statistical language for all analyses (R Core

Team, 2024).

RESULTS

General results: We collected informa-

tion on foraging substrates and maneuvers

employed to capture prey for 12 warbler species

in the mangrove forest. However, only 5 species

had enough sample size to be included in the

analyses (Setophaga p. erithachorides, S. pete-

chia, Protonotaria citrea, Parkesia noveboracen-

sis, and Leiothlypis peregrina). The abundance

of migrants fluctuated over the study period

but it increased rapidly after the first arrivals,

overpassing by far the number of S. p. eritha-

chorides (Fig. 1).

Foraging substrates and foraging maneu-

vers- all species: The time warblers foraged

on each substrate varied widely across spe-

cies (Supplementary Table 2), but with spe-

cies aggregated in two groups. The first group

included S. p. erithachorides, S. petechia and

P. citrea which used the substrates more

homogeneously (lower cv values) than the sec-

ond group that included P. noveboracensis and

L. peregrina (Fig. 2A).

The use of capture maneuvers was more

heterogeneous than the use of substrates as

indicated by higher values of the cv (Fig. 2B;

Supplementary Table 3), but there were some

patterns. Two of the species (S. petechia and

L. peregrina) had higher mean cv values, indi-

cating an even more heterogenous used of

maneuvers than S. p. erithachorides and P. citrea;

with P. noveboracensis having a larger varia-

tion in maneuvers used across foraging ses-

sions. Hence, P. noveboracensis and L. peregrina

showed a narrower preference for substrates

than the other warblers, and S. petechia and

L. peregrina showed a narrower preference for

maneuvers (Fig. 2A-B).

The use of substrates (analyzed with PER-

MANOVA) also indicated a marked difference

across species (Table 1A; Fig. 2C). Parkesia

noveboracensis differed notably from the other

warblers that showed a larger similarity in

the use of different substrates. However, even

within this compact group (Setophaga p. eritha-

chorides, S. petechia, Protonotaria citrea, and

Fig. 1. Abundance of the four (S. petechia, P. citrea, P.

noveroracensis, and L. peregrina) migrant warblers (black

dots) and the resident S. p. erithachorides (white dots).

The absence of migrants (0 individuals) is consequence

of migrants flying to their breeding grounds in North

America.

6Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73 (S1): e64548, mayo 2025 (Publicado May. 15, 2025)

Fig. 2. Comparison of foraging strategies of the five warbler species: Setophaga petechia erithachorides [S.p.e], S. petechia

[S.p], Protonotaria citrea [P.cit], Parkesia noveboracensis [P.nov], and Leiothlypis peregrina [L.pe]. Coefficient of variation

(mean and confidence intervals) calculated for the time warblers used the different foraging substrates (a) and the foraging

maneuvers (b). Use of substrates by the five warbler species (c) and excluding P. noveboracensis (d). Use of foraging

maneuvers by the five warbler species (e), and excluding P. noveboracensis (f). The squares represent the centroids and the

ellipses are the 95% confident intervals.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73 (S2): e64548, mayo 2025 (Publicado May. 15, 2025)

L. peregrina) the foraging substrates used by

L. peregrina differed from those used by S. p.

erithachorides (Table 1B; Fig. 2D).

The use of foraging maneuvers showed

a similar pattern than the use of foraging

substrates. P. noveborascensis stand out from

the other four species which group together

(Table 1C; Fig. 2E). When P. noveborascensis

was excluded from the analysis, L. peregrina

differed in the use of foraging maneuvers with

S. p. erithachorides (Fig. 2F; Table 1D). This

indicated that P. noveborascensis used a set of

substrates and foraging maneuvers that notably

differed from the substrates and maneuvers

used by the other four warbler species. On the

contrary, S. p. erithachorides used a wider range

of substrates and maneuvers than the other spe-

cies (Fig. 2C-F).

Foraging substrates and foraging maneu-

vers- S. p. erithachorides: The foraging sub-

strates used by S. p. erithachorides did not differ

whether the migrant warblers were present or

not (F = 1.26, P = 0.313). However, the used

of foraging maneuvers differed between both

periods (F = 3.55, P = 0.004). When migrants

were present, S. p. erithachorides used more

maneuvers, and slightly more homogeneously

as indicated by cv values (cvpresent = 3.48, cvabsent

= 3.60).

Warblers’ morphology: The morphology

differed between groups of species. S. p. eritha-

chorides, S. petechia, and L. peregrina did not

differ in their morphology (Fig. 3). P. citrea and

P. noveborascensis differed from the two Setoph-

aga and L. peregrina, and P. noveborascensis dif-

fered from the other four species (Fig. 3).

DISCUSION

Behavioral ecology studies often provide

relevant information on the factors underlying

the coexistence of closely related species. In this

study warblers exhibited foraging strategies that

differed remarkably among species in a man-

grove forest. There are two well-defined groups

(Fig. 2C-F); one of such groups includes only

a single species, the ground foraging Parkesia

noveborascensis, which stands out from the

rest of species. This is a species that forages

primarily on the ground, gleaning for insects

Table 1

Use of foraging substrates and foraging maneuvers by five warbler species (Setophaga p. erithachorides, S. petechia,

Protonotaria citrea, Parkesia noveboracensis, and Leiothlypis peregrina) in a mangrove forest.

ASubstrates use: all species

Factor DF Sum of squares R2F P

Species 4 12.31 0.76 80.41 0.001

Residual 102 3.90 0.24

Total 106 16.22 1.00

BSubstrate use: excluding P. noveborascensis

Species 3 1.08 0.27 10.27 0.001

Residual 83 2.92 0.73

Total 86 4.00 1.00

CForaging maneuvers: all species

Species 4 10.65 0.72 66.70 0.001

Residual 103 4.11 0.28

Total 107 14.76 1.00

DForaging maneuvers: excluding P. noveborascensis

Species 3 0.88 0.25 9.15 0.001

Residual 83 2.66 0.75

Total 86 3.54 1.00

8Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73 (S1): e64548, mayo 2025 (Publicado May. 15, 2025)

and other invertebrates on bare soil or in the

litter. The other warblers form a more compact

group (Supplementary Table 2). They primar-

ily forage by gleaning prey from leaves and

twigs, but there are some differences between

S. p. erithachorides and L. peregrina. Although,

both species forage mostly by gleaning, S. p.

erithachorides glean 45% of its time on leaves

and 46% of its time on twigs, while L. peregrina

glean 80% of its time on leaves, making the

foraging of this species different from the other

species in the group (Fig. 2, Supplementary

Table 3).

Morphology is usually associated with par-

ticular foraging strategies and microhabitat

use in different groups of species (Brandl,

et al., 1994, Fitzpatrick, 1985; Losos, 1990c;

Moermond & Denslow, 1985; Norberg, 1994).

Hence, species with similar morphologies, as

a result of closely phylogenetic relatedness (or

convergent evolution) tend to occupy similar

microhabitats and use similar foraging strate-

gies (Brandl, et al., 1994, Losos, 1990c). Within

the studied warblers, the most distant species

(i.e., P. noveboracensis) has the most discrepant

morphology and foraging strategy (Lovette &

Bermingham, 1999; Klein et al., 2004; Lovette

et al., 2010). Protonotaria citrea and L. per-

egrina (= Vermivora peregrina) are, each one,

placed in a different clade but both closer to

the Setophaga (= Dendroica) clade than P. n o v e -

borascensis (Lovette et al., 2010). Protonotaria

citrea differed morphologically from Setophaga

species, but the morphology of Leiothlypis is

similar to that of Setophaga spp. However, Pro-

tonotaria have a similar foraging strategy than

both Setophaga species, despite their morpho-

logical differences, while the foraging pattern

of L. peregrina differed at least from that of S.

p. erithachorides, despite their high similarity

in morphology. In the case of Setophaga, both

taxa have similar morphology and similar for-

aging strategies. Therefore, although morphol-

ogy associates with similar foraging strategies

in this group of warblers, there are some subtle

differences in foraging patterns likely deter-

mined by species specific foraging adaptations

(e.g., preference for certain prey type) or other

morphological features (e.g., wing loading) not

considered in this study.

The foraging strategy of S. p. erithacho-

rides changes when migrants arrive. The use of

foraging substrates does not change but there

was a tendency to use other foraging maneu-

vers (e.g., gleaning of the ground) or use some

maneuvers more frequently (e.g., hanging, hov-

ering) when migrants were present. Competi-

tion is usually advocated to explain changes in

habitat use and foraging behavior, particularly

when species interact with similar and abun-

dant counterparts with similar morphology and

foraging strategies (Bennett, 1980; Cody 1985;

Diamond, 1978; MacArthur, 1958). However,

other factors may usually explain the changes

in habitat or foraging strategies attributed ini-

tially to interspecific competition (Morse, 1985;

Strong, 1984; Wiens, 1989). For instance, the

period of winter residence coincides with the

period of minimal insect abundance in north-

western Costa Rica (Hespenheide, 1980; Jan-

zen, 1980). This fact could be enough to change

the foraging strategy of S. p. erithachorides dur-

ing the wintering period of migratory warblers,

if birds focus on other (or more) prey types.

Thus, more generalist behavior is expected

Fig. 3. Comparison of the morphology, represented by the

median, lower, and upper quantiles of PC1 scores, of the

five warbler species.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73 (S2): e64548, mayo 2025 (Publicado May. 15, 2025)

when resource availability decreases (Carpenter

& MacMillen, 1976; Grant, 1993), but further

evidence is required to support this hypothesis.

Differences and similarities in the foraging

strategies of the five warbles species match the

species’ morphology. This suggests that the for-

aging strategy of each species has been molded

by different (or similar) adaptation processes

along the evolution of each species or group.

Therefore, species that have occupied the same

adaptive landscape or are constrained by their

recent ancestry—such as S. p. erithachorides and

S. petechia (Chavarria-Pizarro et al., 2019)—are

expected to exhibit more similar morphologies

and foraging strategies. Our results provide

little support for the niche partitioning hypoth-

esis, as similar species (morphologically and/

or phylogenetically) use the habitat similarly—

contrary to the prediction that similar species

would use the habitat differently. Competition

cannot be entirely excluded, but it would be

only one aspect, like predation and seasonal

changes in resources, of the adaptive scape in

which each species evolved.

Ethical statement: the authors declare that

they all agree with this publication and made

significant contributions; that there is no con-

flict of interest of any kind; and that we fol-

lowed all pertinent ethical and legal procedures

and requirements. All financial sources are fully

and clearly stated in the acknowledgments sec-

tion. A signed document has been filed in the

journal archives.

See supplementary material

a10v73s2-suppl1

ACKNOWLEDGMENTS

We thank José Pablo Marín for measur-

ing the morphology of warbler specimens.

LS thanks the Vicerrectoría de investigación,

Universidad de Costa Rica for the support to

conduct this investigation under project num-

ber C2706.

REFERENCES

Barrantes, G. (1998). Biología y comportamiento de la

reinita de manglar (Dendroica petechia xanthotera).

Brenesia, 49-50, 61–69.

Bennett, S. E. (1980). Interspecific competition and niche

of the American Redstart (Setophaga ruticilla) in

wintering and breeding communities. In A. Keast & E.

S. Morton (Eds.), Migrant birds in the Neotropics (pp.

319–335). Smithsonian Institution Press.

Brandl, R., Kristín, A., & Leisler, B. (1994). Dietary niche

breadth in a local community of passerine birds: An

analysis using phylogenetic contrasts. Oecologia, 98,

109–116.

Carpenter, F. L., & MacMillen, R. E. (1976). Threshold

model of feeding territoriality and test with a

Hawaiian honeycreeper. Science, 194, 639–642.

Chavarria-Pizarro, T., Gomez, J. P., Ungvari-Martin, J., Bay,

R., Miyamoto, M. M., & Kimball, R. (2019). Strong

phenotypic divergence in spite of low genetic struc-

ture in the endemic Mangrove Warbler subspecies

(Setophaga petechia xanthotera) of Costa Rica. Ecology

and Evolution, 9, 13902–13918.

Cody, M. L. (1985). An introduction to habitat selection in

birds. In M. L. Cody (Ed.), Habitat selection in birds

(pp. 4–46). Academic Press.

Diamond, J. M. (1978). Niche shifts and the rediscovery of

interspecific competition: Why did field biologists so

long overlook the widespread evidence for interspeci-

fic competition that had already impressed Darwin?

American Scientist, 66, 322–331.

Epifanio, C. E., Murer, E., & Dittel, A. (1983). Seasonal

changes in nutrients and dissolved oxygen in the Gulf

of Nicoya, a tropical estuary on the Pacific coast of

Central America. Hidrobiologia, 101, 231–238.

Fitzpatrick, J. W. (1980). Foraging behavior of neotropical

tyrant flycatchers. Condor, 82, 43–57.

Fitzpatrick, J. W. (1985). Form, foraging behavior, and

adaptive radiation in the Tyrannidae. Ornithological

Monographs, 36, 447–470.

Grant, J. W. A. (1993). Whether or not to defend? The

influence of resource distribution. Ecology, 74,

171–179.

Hespenheide, H. A. (1980). Bird community structure in

two Panama forests: Residents, migrants, and seaso-

nality during the nonbreeding season. In A. Keast &

E. S. Morton (Eds.), Migrant birds in the Neotropics

(pp. 227–237). Smithsonian Institution Press.

Holmes, R. T., Bonney, R. E., & Pacala, S. W. (1979). Guild

structure of the Hubbard Brook bird community: A

multivariate approach. Ecology, 60, 512–520.

10 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 73 (S1): e64548, mayo 2025 (Publicado May. 15, 2025)

Janzen, D. H. (1980). Heterogeneity of potential food abun-

dance for tropical small land birds. In A. Keast & E.

S. Morton (Eds.), Migrant birds in the Neotropics (pp.

545–552). Smithsonian Institution Press.

Jiménez, J. A., & Soto, R. (1985). Patrones regionales en la

estructura y composición de los manglares de la costa

pacífica de Costa Rica. Revista Biología Tropical, 33,

25–37.

Keast, A. (1980). Spatial relationship between migratory

parulid warblers and their ecological counterparts

in the neotropics. In A. Keast & E. S. Morton (Eds.),

Migrant birds in the Neotropics (pp. 109–130). Smith-

sonian Institution Press.

Klein, N. K., Burns, K. J., Hackett, S. J., & Griffiths, C. S.

(2004). Molecular phylogenetic relationships among

the wood warblers (Parulidae) and historical biogeo-

graphy in the Caribbean basin. Journal of Caribbean

Ornithology, 17, 3–17.

Lenth, R., Singmann, H., Love, J., Buerkner, P., & Herve,

M. (2018). Emmeans (Version 4.0-3) [Com-

puter software]. https://CRAN.R-project.org/

package=emmeans

Losos, J. B. (1990a). Phylogenetic analysis of character

displacement in Caribbean Anolis lizards. Evolution,

44, 558–569.

Losos, J. B. (1990b). The evolution of form and function:

Morphology and locomotion performance in West

Indian Anolis lizards. Evolution, 44, 1189–1203.

Losos, J. B. (1990c). Ecomorphology, performance capa-

bility, and scaling of West Indian Anolis lizards:

An evolutionary analysis. Ecological Monographs, 60,

369–388.

Losos, J. B., & Miles, D. B. (1994). Adaptation, constraint,

and the comparative method: Phylogenetic issues and

methods. In P. C. Wainwright & S. M. Reilly (Eds.),

Morphological ecology: Integrative organismal biology

(pp. 60–98). University of Chicago Press.

Lovette, I. J. & Bermingham, E. (1999). Explosive specia-

tion in the New World Dendroica warblers. Procee-

dings of the Royal Society B: Biological Sciences, 266,

1629–1636.

Lovette, I. J. Pérez-Emán, J. L., Sullivan, J. P., Banks, R. C.,

Fiorentino, I., Córdoba-Córdoba, S., Echeverry-Gal-

vis, M., Barker, K. F., Burns, K. J., Klicka, J., Lanyon,

S. M., & Bermingham, E. (2010). A comprehensive

multilocus phylogeny for the wood-warblers and a

revised classification of the Parulidae (Aves). Molecu-

lar Phylogenetics and Evolution, 57, 753–770.

Lowther, P. E., Celada, C., Klein, N. K., Rimmer, C. C., &

Spector, D. A. (1999). Yellow Warbler (Dendroica

petechia). In A. Poole & F. Gill (Eds.), The Birds of

North America (No. 454). Birds of North America,

Philadelphia.

MacArthur, R. H. (1958). Population ecology of some

warblers of northeastern coniferous forests. Ecology,

39, 599–619.

MacArthur, R. H. (1972). Geographical ecology: Patterns in

the distribution of species. Princeton University Press.

Miller, R. S. (1967). Patterns and processes in competition.

Advances in Ecological Research, 4, 1–74.

Moermond, T. C., & Denslow, J. S. (1985). Neotropical

avian frugivores: Patterns of behavior, morphology,

and nutrition, with consequences for fruit selection.

In M. L. Cody (Ed.), Habitat selection in birds (pp.

865–897). Academic Press.

Morse, D. H. (1985). Habitat selection in North American

parulid warblers. In M. L. Cody (Ed.), Habitat selec-

tion in birds (pp. 131–157). Academic Press.

Norberg, U. (1994). Wing design, flight performance, and

habitat use in bats. In P. C. Wainwright & S. M. Reilly

(Eds.), Morphological ecology: Integrative organismal

biology (pp. 205–239). University of Chicago Press.

Oksanen, J., Blanchett, F. G., Friendly, M., Kindt, R., Legen-

dre, P., McGlinn, D. P. R., O’Hara, M. R. B., Simpson,

G. L., Solymos, P., Stevens, M. H. H., Szoecs, E., &

Wagner, H. (2020). Vegan: Community ecology pac-

kage (Version 2.6-6.1) [Computer software]. CRAN.

https://CRAN.R-project.org/package=vegan

Pianka, E. C. (1994). Evolutionary ecology. Harper Collins.

R Core Team. (2024). R: A language and environment

for statistical computing (Version 4.4.0) [Computer

software]. R Foundation for Statistical Computing.

https://www.R-project.org/.

Remsen, J. V., & Robinson, S. K. (1990). A classification

scheme for foraging behavior or birds in terrestrial

habitats. Studies in Avian Biology, 13, 144–160.

Ricklefs, R. E., & Miles, D. B. (1994). Ecological and evolu-

tionary inferences from morphology: An ecological

perspective. In P. C. Wainwright & S. M. Reilly (Eds.),

Morphological ecology: Integrative organismal biology

(pp. 13–41). University of Chicago Press.

Robinson, S. K., & Holmes, R. T. (1982). Reviewed Fora-

ging behavior of forest birds: the relationships among

search tactics, diet, and habitat structure. Ecology, 63,

1918–1931.

Strong, D. R. (1984). Exorcising the ghost of competition

past: Phytophagous insects. In D. R. Strong, D. Sim-

berloff, L. G. Abele, & A. B. Thistle (Eds.), Ecological

communities: Conceptual issues and the evidence (pp.

28–41). Princeton University Press.

Tilman, D. (1987). The importance of the mechanisms of

interspecific competition. American Naturalist, 129,

769–774.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 73 (S2): e64548, mayo 2025 (Publicado May. 15, 2025)

Tilman, D. (1994). Competition and biodiversity in spatia-

lly structured habitats. Ecology, 75, 2–16.

Wiens, J. A. (1989). The ecology of bird communities: Foun-

dation and patterns. Cambridge University Press.

Winkler, H., & Leisler, B. (1985). Morphological aspects of

habitat selection in birds. In M. L. Cody (Ed.), Habitat

selection in birds (pp. 415-434). Academic Press.

Wise, D. H. (1993). Spiders in ecological webs. Cambridge

University Press.