Abundance, diet and food availability of Citreoline Trogon (Trogon citreolus) in a regenerating tropical dry forest in the Central Pacific, Mexico

Abstract

Trogonidae make up a family of birds with a mixed diet composed of fruit and animal matter. However, there is little research examining the foraging ecology of Trogon citreolus in regenerating tropical forest. We studied T. citreolus abundance and diet from November 2020 to April 2022 in a regenerating dry tropical forest of Central Pacific Mexico. Also, we investigate the relationship between food availability and trogon abundance. The relative trogon abundance was 2.6 ± 2.3 individuals per point count, which varied temporally. The species consumed the fruits of 14 plant species from 10 families. The three most consumed species were Ficus cotinifolia, Comocladia engleriana, and Randia gentlei. Trogon citreolus displayed a moderate niche breadth (Best = 0. 420) whit low food diet diversity (H’ = 0.94), and the dominance of a particular type of food (λ = 0.85). Our results demonstrated a positive correlation between trogon abundance and food resource availability. The dietary breadth of T. citreolus enable the species to adapt to fluctuations in fruit availability in regenerating forests. These findings highlight the ecological importance of forest regeneration in providing food resources for T. citreolus and other frugivorous birds.

Full text

411
Abundance, diet and food availability of Citreoline Trogon (Trogon
citreolus) in a regenerating tropical dry forest in the Central
Pacic, Mexico
Esmeralda Floreán-Díaz1, Miguel Angel De Labra-Hernández2
1 División de Estudios de Posgrado, Maestría en Ciencias: Manejo de Fauna Silvestre, Universidad del Mar campus Puerto Escondido, San Pedro Mixtepec,
Oaxaca, Mexico
2 Instituto de Ecología, Universidad del Mar campus Puerto Escondido, San Pedro Mixtepec, Oaxaca, Mexico
Corresponding author: Miguel Ángel De Labra-Hernández (m.delabrah@gmail.com)
Copyright: © Esmeralda Floreán-Díaz &
Miguel Ángel De Labra-Hernández.
This is an open access article distributed under
terms of the Creative Commons Attribution
License (Attribution 4.0 International – CC BY 4.0).
Research Article
Abstract
Trogonidae make up a family of birds with a mixed diet composed of fruit and animal
matter. However, there is little research examining the foraging ecology of Trogon cit-
reolus in regenerating tropical forest. We studied T. citreolus abundance and diet from
November 2020 to April 2022 in a regenerating dry tropical forest of Central Pacic
Mexico. Also, we investigate the relationship between food availability and trogon abun-
dance. The relative trogon abundance was 2.6 ± 2.3 individuals per point count, which
varied temporally. The species consumed the fruits of 14 plant species from 10 fami-
lies. The three most consumed species were Ficus cotinifolia, Comocladia engleriana,
and Randia gentlei. Trogon citreolus displayed a moderate niche breadth (Best = 0. 420)
whit low food diet diversity (H’ = 0.94), and the dominance of a particular type of food
(λ = 0.85). Our results demonstrated a positive correlation between trogon abundance
and food resource availability. The dietary breadth of T. citreolus enable the species to
adapt to uctuations in fruit availability in regenerating forests. These ndings high-
light the ecological importance of forest regeneration in providing food resources for
T. citreolus and other frugivorous birds.
Key words: Frugivorous birds, fruit availability, Levins index, phenology transects,
successional dry forest, Trogonidae
Introduction
In the context of regenerating forests, an understanding of how birds utilize
food resources and their responses to changes in food availability is of signif-
icant value for the effective management of habitats and the conservation of
species (Fleming 1992). In tropical birds, there is evidence that food availability
is related to temporal changes in abundance, and also inuences foraging be-
havior (Levey 1988; Loiselle 1988). Trogons and quetzals (Trogonidae) inhabit
the tropical regions of America, Asia, and Africa. The Trogonidae family com-
prises 46 species, 25 of which are found in the Neotropical region, including
nine species distributed in Mexico (Winkler et al. 2020). These birds have a
Academic editor: Piter Boll
Received:
29 May 2024
Accepted:
9 September 2024
Published:
2 October 2024
ZooBank: https://zoobank.
org/9EF0CD1C-D642-4ABC-839B-
82A5151A5877
Citation: Floreán-Díaz E, De Labra-
Hernández MA (2024) Abundance,
diet and food availability of Citreoline
Trogon (Trogon citreolus) in a
regenerating tropical dry forest in the
Central Pacic, Mexico. Neotropical
Biology and Conservation 19(4):
411–425. https://doi.org/10.3897/
neotropical.19.e128529
Neotropical Biology and Conservation 19(4): 411–425 (2024)
DOI: 10.3897/neotropical.19.e128529

412
Neotropical Biology and Conservation 19(4): 411–425 (2024), DOI: 10.3897/neotropical.19.e128529
Esmeralda Floreán-Díaz & Miguel Ángel De Labra-Hernández: Abundance and diet of Trogon citreolus
mixed diet composed of fruits from diverse tropical plants and animal items
such as caterpillars, insects, and small vertebrates (Remsen et al. 1993; Avi-
la et al. 1996; del Hoyo et al. 2001; Pizo 2007; Riehl and Adelson 2008). The
inuence of fruit availability on population density and altitudinal migration
patterns in this avian group has been documented, as demonstrated by the
quetzal (Pharomachrus mocinno) within its breeding range in Costa Rica and
southeastern Mexico (Wheelwright 1983; Solórzano et al. 2000).
Among trogon species, the Citreoline Trogon (Trogon citreolus Gould, 1835),
an endemic species of Mexico, is found along the Pacic slope from Sinaloa to
northwestern Chiapas, mainly associated with tropical dry and semi-deciduous
forest, mangroves and secondary growth forests (Howell and Webb 1995; Col-
lar 2020). The Citreoline Trogon has been observed to consume both fruits and
small invertebrates as part of its diet (Skutch 1948). Eguiarte and Martínez del Rio
(1985) observed that the Citreoline Trogon exhibited a frugivorous diet during the
dry season in preserved forests in Mexico. Other studies indicate that the species
exhibits plasticity in the use of food resources throughout the year, including the
consumption of fruits from February to June, insects from July to October, and a
combination of fruits and insects from November to January (Morán-Dimayuga
2002; Collar 2020). Nevertheless, there has been a paucity of research examining
the foraging ecology of T. citreolus in regenerating forest ecosystems. Identifying
the tree species that comprise the Citreoline Trogon’s diet in these habitats is
crucial for developing effective long-term habitat-management strategies.
The Citreoline Trogon is not legally protected by Mexican laws (SEMARNAT
2010) and there is no published information regarding their abundance (Collar
2020). In this paper, we aimed to determine the relative abundance and diet
of T. citreolus, the relationships between food sources availability and trogon
abundance in a regenerating dry tropical forest of Central Pacic, Mexico. We
tested the hypothesis that food resource availability affects the abundance
and foraging behavior of T. citreolus. Additionally, we predicted that changes
in T. citreolus abundance are related to local fruiting patterns, with some plant
species having the highest frequency of consumption.
Materials and methods
Study area
The study was conducted at the Puerto Escondido Botanical Garden of the Uni-
versidad del Mar (hereafter JBPE), in the coastal plain of Oaxaca, southwest-
ern Mexico (15°54'41.7"N, 97°04'29.2"W; 15°55'1.0"N, 97°04'52.9"W; Fig. 1).
The JBPE consists of 16.7 hectares intended for the study and conservation of
regional biodiversity (Fig. 1A). The site was previously used for planting corn,
beans, sesame, and pumpkin between 1972 and 1983. In 2004, the municipal
government donated the area to the Universidad del Mar (Luis-Reyna 2018). The
site is distinguished by the presence of a rugged topography, with hills that range
in elevation from 70 to 160 masl and small ravines that traverse the site.The
area is currently dominated by tropical dry forest (Rzedowski 2006) that has un-
dergone 20 years of secondary succession, allowing for vegetation repopulation
(Fig. 1B). The most common plant families include Anacardiaceae, Annonaceae,
Burceraceae, Fabaceae, and Rubiaceae. Common tree species in the area are

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Neotropical Biology and Conservation 19(4): 411–425 (2024), DOI: 10.3897/neotropical.19.e128529
Esmeralda Floreán-Díaz & Miguel Ángel De Labra-Hernández: Abundance and diet of Trogon citreolus
Bursera simaruba, Ceiba parvifolia, Cochlospermun vitifolium, Comocladia en-
gleriana, Guapira macrocarpa, and Tabebuia chrysantha (Luis-Reyna 2018). The
region is characterized by a warm, subhumid climate with summer rains. There
are two distinct seasons, the dry season from November to May and the wet
season from June to October. The average annual temperature ranges from 22
to 43.2 °C, and precipitation ranges between 800 to 1000 mm (Trejo 2004).
Abundance and diet of Trogon citreolus
From November 2020 to April 2021, we counted individuals of T. citreolus using
the point counts method with a xed radius of 30 m (Bibby et al. 1992; Gildardi
and Munn 1998). We established 15-point counts, which were geo-referenced
using GPS, to maintain a distance of 150 m between points and ensure the in-
dependence of the records (Fig. 1). At each point, we conducted a 10 min count
to record all individuals of T. citreolus seen and heard. The sound records were
considered for a single individual, regardless of group size. For each record, we
noted the date, time, number of individuals, activity (hatch, ight), and foraging
observations. Counts were conducted by a single person (EFD) in the morning
from 6:00 to 10:00 h and in the evening from 16:30 to 18:30 h.
We determined diet through focal observations of foraging trogon during
the same period and time as the point counts. We also considered opportunis-
tic observations of foraging trogon when these were encountered outside the
point counts. For each forage record, we noted: (1) date and time; (2) number
of individuals; and (3) tree species. We considered a foraging record as one
or more individuals feeding on a tree; when the individuals moved to another
resource of the same tree or another tree, this was considered a second forag-
ing record (Galetti 1993). Foraging records were carried out by a single person
using binoculars (MADLH).
Food resource availability
We established 10 phenological transects (100 × 4 m) (Fig. 1) to determine
food resource availability for trogons (Chapman et al. 1992). Phenological tran-
sects were visited monthly from November 2020 to April 2021. In transects, all
fruit trees or shrubs were marked and identied. For each fruiting tree or shrub,
we measured the diameter at breast height (DBH) and estimated the propor-
tion of fruits in the crown based on four categories (1 = 0–25%; 2 = 26–50%;
3 = 51–75% and 4 > 75%) (Chapman et al. 1994). We calculated a fruit abun-
dance index by multiplying tree DBH by the proportion of the canopy with fruits
(∑ (DBH * proportion of fruits)/number of transects) (Chapman et al. 1992).
Additionally, for each transect, we considered the number of tree species fruit-
ing, the number of fruiting trees/shrubs, and the sum of the fruit abundance
index, as variables of food resource abundance that could be compared among
months. Tree and shrub species were identied in the eld or by means of bo-
tanical sampling collected for later identication at the Laboratory of Biological
Collections of the Universidad del Mar, campus Puerto Escondido. Tree iden-
tication and nomenclature followed Salas-Morales et al. (2003), Pennington
and Sarukhán (1998), Salas-Morales et al. (2007), García-Mendoza and Meave
(2011), and Pérez and Barajas-Morales (2011).

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Neotropical Biology and Conservation 19(4): 411–425 (2024), DOI: 10.3897/neotropical.19.e128529
Esmeralda Floreán-Díaz & Miguel Ángel De Labra-Hernández: Abundance and diet of Trogon citreolus
Statistical analysis
The relative abundance of T. citreolus was calculated monthly (November 2020
to April 2021) by dividing the number of individuals recorded per point count
by the total point counts. Due to the data not meeting the assumption of nor-
mality (Shapiro-Wilk) even with logarithmic transformation, we compared the
relative abundance of T. citreolus using the Friedman nonparametric test and
Tukey-Kramer post hoc test with Bonferroni adjustments, to identify the pat-
tern of change in abundance over the study period (Quinn and Keough 2002).
Foraging records were used to estimate the food-niche breadth of T. citreolus
using the Levins standardized index (Best = (B - 1) / (n - 1); where B = 1 / Σpi
2 y
pi = proportion of individuals using the resource i (Levins 1968; Hulbert 1978).
This index expresses the niche breadth on a scale from 0 (narrow niche), indi-
cating that the use is concentrated on a few resources, to 1 (wide niche), when
the resources are equally used (Colwell and Futuyma 1971). The niche breadth
quanties the species’ specialization within a given environment (Krebs 1999).
To describe diet diversity, we calculated Shannon-Wiener’s index, H’ = Σ pi ln pi,
and Simpson index, λ = 1-Σ(pi)2 (Sherry 1990). In regard to the Shannon-Wiener
index, the following arbitrary criteria were employed: (a) if the value H’ > 3, it is
dened as high food diversity; (b) if the H’ value is within the 1–3 interval, it is
Figure 1. Location of the Puerto Escondido Botanical Garden of the Universidad del Mar, coastal plain of Oaxaca,
southwestern Mexico. The point counts are indicated with “P” and the phenological transects with “T”. (A) the area
covered by the Botanical Garden. (B) example of the plant structure.

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Neotropical Biology and Conservation 19(4): 411–425 (2024), DOI: 10.3897/neotropical.19.e128529
Esmeralda Floreán-Díaz & Miguel Ángel De Labra-Hernández: Abundance and diet of Trogon citreolus
dened as moderate food diversity; and (c) if the value of H’ < 1, it is dened as
low food diversity. The criteria for the Simpson index value are: (a) if the λ value
is close to 0, no particular food type dominates, and (b) if the λ value is close to
1, there is a particular food type that dominates.
Additionally, we compared the fruit availability recorded in the 10 phenologi-
cal transects in terms of the number of species fruiting, the number of fruiting
trees, and the sum of a fruit abundance index, to evaluate whether there was
variation in resource availability. We performed either parametric tests (repeat-
ed-measures ANOVA) or non-parametric tests (Friedman), according to the nor-
mality of the data (Shapiro-Wilk), and when signicant differences occurred,
we applied the post hoc Tukey-Kramer test to determine which group produced
a signicant difference among months (Quinn and Keough 2002). Ultimately,
Pearson’s correlation test was employed to ascertain the relationship between
T. citreolus abundance and fruit availability for all trees, as well as fruit availabil-
ity for diet trees (Zar 1999). The analyses considered the fruit abundance index
and the number of individuals recorded per point count for each month. To en-
sure consistency in the analysis, the trogon abundance recorded at points 1–2,
4–5, 8–11, 9–10, and 14–15, which were near phenology transects (Fig. 1), was
averaged. This adjustment allowed for an identical number of phenology tran-
sects and point counts (n = 10). Analyses were carried out using R statistical
software with the package “rstatix” (R Core Team 2016). Descriptive statistics
are presented as mean with standard deviation, and we considered P < 0.05 as
signicance differences in statistical analyses.
Results
Trogon citreolus abundance
During the study period, we obtained a total of 159 records of T. citreolus. The
largest number of records occurred in April (n = 46; 28.9%), followed by March
(n = 29; 18.2%), and the smallest number occurred in December (n = 16; 10.1%).
The relative abundance of T. citreolus was 2.6 ± 2.3 individuals per point count.
T. citreolus exhibited a steady pattern of abundance (November 2021–March
2022), with an increase at the end of the study period in April 2022. The Fried-
man test indicated that signicant differences in trogon abundance occurred
between months (Friedman X2
5 = 11.32, P = 0.045; Fig. 2). The Tukey post hoc
test showed that trogon abundance was signicantly higher in April (3.9 ± 2.5
individuals; n = 59; interval: 0–9), compared to December (Q = 4.07, P < 0.05),
the month with the lowest abundance (1.1 ± 1.0 individuals; n = 17; interval:
0–3). No other comparisons were signicant (P > 0.05).
Trogon diet and food niche breadth
We obtained a total of 41 foraging records of T. citreolus (n = 88 individuals),
consuming 14 plant species from 10 families (Table 1). Only fruit consump-
tion was recorded during the foraging observations, and no other items were
consumed. The most common plant families in the trogon diet were Anacardi-
acae (34.1%; n = 19 individuals), Rubiaceae (17.1%; n = 21 individuals), Mora-
ceae (12.3%; n = 24 individuals), and Vitacae (9.8%; n = 6 individuals) (Table 1).

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Neotropical Biology and Conservation 19(4): 411–425 (2024), DOI: 10.3897/neotropical.19.e128529
Esmeralda Floreán-Díaz & Miguel Ángel De Labra-Hernández: Abundance and diet of Trogon citreolus
Among the plant species listed in Table 1, 57.2% correspond to mature decid-
uous tropical forest species, while 42.8% are common in regenerating forests
(Pennington and Sarukhán 1998; Rzedowski 2006).
Considering the number of trogons using each food resource, we calculated
an overall Levins´ niche breadth of Best = 0.420. This represents a moderate
niche breadth where use was spread relatively equally over the resources, with
six plant species contributing > 5% of the diet. Nevertheless, three plant species
Table 1. Diet of Trogon citreolus in the regenerating dry tropical forest of the Puerto Escondido Botanical Garden, coastal
plain of Oaxaca, southwestern Mexico, from November 2021 to April 2022. The percentage (%) is shown in parentheses.
Family Specie Common name Foraging
records
Number of
individuals Month
Anacardiaceae Comocladia engleriana Loes. Tetlatia 12 (29.3) 17 (19.3) February–March 2021
Spondias purpurea L. Mexican plum 2 (4.9) 2 (2.3) April 2021
Apocynaceae Tabernaemontana grandiora Jacq. Wedding tree 1 (2.4) 1 (1.1) December 2020
Burseraceae Bursera simaruba (L.) Sarg. Gumbo limbo 1 (2.4 1 (1.1) January 2021
Ebenaceae Diospyros verae-crucis (Standl.)
Standl.
Willow Leaf
Persimmon
3 (7.3) 4 (4.5) November 2020,
January 2021
Moraceae Ficus cotinifolia Kunth Poplar tree 5 (12.2) 24 (27.3) January 2021
Passioraceae Passiora sp. Passionfruit 3 (7.3) 6 (6.8) December 2020,
January 2021
Polygonaceae Coccoloba barbadensis Jacq. Fresh watergrape 1 (2.4) 2 (2.3) February 2021
Coccoloba liebmannii Lindau Liebmann´s seagrape 1 (2.4) 3 (3.4) February 2021
Resedaceae Forchhammeria pallida Liebm. Olive tree 1 (2.4) 1 (1.1) January 2021
Rubiaceae Hamelia longipes Standl Long-stemmed
Firebush
1 (2.4) 2 (2.3) February 2021
Hintonia latiora (Sesse & Moc. Ex.
DC.) Bullock
Bitter tree 3 (7.3) 5 (5.7) January 2021
Randia gentlei Lundell Wild calabas 3 (7.3) 14 (15.9) December 2020,
January 2021
Vitaceae Ampelocissus acapulcensis (Kunth)
Planch
Grape vine 4 (9.8) 6 (6.8) March – April 2021
Figure 2. Relationship between fruit abundance index and abundance of Trogon citre-
olus in the tropical regenerating dry forest of the Puerto Escondido Botanical Garden
from November 2020 to April 2021.

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Neotropical Biology and Conservation 19(4): 411–425 (2024), DOI: 10.3897/neotropical.19.e128529
Esmeralda Floreán-Díaz & Miguel Ángel De Labra-Hernández: Abundance and diet of Trogon citreolus
contributed more than 60% of the trogon diets, with more individuals recorded
consuming fruits of Ficus cotinifolia (n = 24 individuals; 27.3%), Comocladia
engleriana (n = 17 individuals; 19.3%), and Randia gentlei (n = 14 individuals;
15.9%) (Table 1). The Shannon-Wiener Index showed low food diet diversity
(H’ = 0.94), and the Simpson Index showed the dominance of a particular type
of food (λ = 0.85), F. cotinifolia exhibited the highest frequency of consumption
by T. citreolus.
Temporal variation in food resource availability
We recorded 266 trees of 28 species from 13 families in the phenology tran-
sects (See Suppl. material 1). Plant families with the largest number of tree
species fruiting were Fabaceae (n = 23 species), Rubiaceae (n = 9 species),
Polygonaceae (n = 5 species), Apocynaceae (n = 4 species), and Bignonaceae
(n = 4 species). Figure 3 illustrates the phenological patterns of the diet trees
(n = 9) of the T. citreolus documented at the study area. The most abundant diet
trees fruiting in November and December 2021 were Randia gentlei, Diospyros
verae-crucis, and Tabernaemontana grandiora, in January and February 2022
were D. verae-crucis, and Coccoloba liebmannii and in March and April 2022
were D. verae-crucis, and Spondias purpurea. Hintonia latiora and Coccoloba
barbadensis only fruited during November and April, respectively. On the other
hand, four species that are part of T. citreolus diet were not recorded in the
phenology transects (Table 1). However, we observed the presence of fruits on
Ficus cotinifolia and Forchhammeria pallida in January, Passiora sp. in Decem-
ber-January, and Ampelocissus acapulcensis in March.
Considering all fruiting trees, there were signicant differences in food re-
source availability during the sampling period. This was evidenced in the
number of tree species fruiting (F5,59 = 17.8, P < 0.001), the number of trees
fruiting (F5,59 = 3.4, P = 0.011), and fruit abundance index (Friedman X2
5 = 38.7,
P < 0.001) (Table 2). Post hoc test (Tukey-Kramer) found signicantly more tree
species fruiting and a larger number of trees fruiting in November and April. In
terms of fruit abundance index, there was a signicant increase during March
to April (Table 2).
Figure 3. Fruiting phenology of nine tree and shrub species consumed by Trogon citre-
olus at Puerto Escondido Botanical Garden, Oaxaca, Mexico, from November 2020 to
April 2021. Thick lines indicate high density of fruiting individuals (>5 individuals/0.4 ha),
and thin lines indicate low density of fruiting individuals.

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Esmeralda Floreán-Díaz & Miguel Ángel De Labra-Hernández: Abundance and diet of Trogon citreolus
Relationship of food resource availability with Trogon citreolus
abundance
In general, the months in which T. citreolus was abundant were those corre-
sponding to the highest fruit availability (Fig. 2). The total fruit abundance index
recorded in phenology transects and the number of trogons per point count in
each month exhibited a signicant correlation (r = 0.61; P < 0.001). Similarly, a
signicant correlation was observed between the availability of tree fruit diet
only and the abundance of T. citreolus (r = 0.68; P < 0.001). From January to
April, T. citreolus showed an increase in abundance and fed most frequently
on Comocladia engleriana (19.3% in February–March), Ficus cotinifolia (27.3%
in January), Passiora sp. (6.8% in November–January), Randia gentlei (15.9%
in December–January), and Ampelocissus acapulcensis (6.8% in March-April).
Discussion
Abundance and diet of Trogon citreolus
This study presents the rst report on the abundance of T. citreolus in a regen-
erating tropical dry forest in the Mexican Pacic. The abundance of T. citreolus
exhibited notable variation throughout the study period, with a marked increase
observed in March and April, which corresponds to the end of the dry season.
The observed variation in T. citreolus abundance may be associated with uc-
tuations in the availability of food resources in the study area, as demonstrated
in previous studies on the quetzal (Solórzano et al. 2000) and other frugivorous
birds (Levey 1988; Blendinger et al. 2012).
The Citreoline Trogon consumed the fruits of 14 plant species, mostly of Fi-
cus cotinifolia, Comocladia engleriana and Randia gentlei, possibly due to their
high nutritional value (Stiles 1993). Ficus cotinifolia, C. engleriana, Spondias pur-
purea, and Forchhammeria pallida have been reported as part of this species´
diet in conserved areas of tropical dry forest off the coast of Jalisco (Eguiarte
and Martínez del Rio 1985; Morán-Dimayuga 2002). In particular, F. cotinifolia
and C. engleriana are the species with the highest percentage of consumption
by T. citreolus during the dry season on the coast of Jalisco (Morán-Dimayuga
2002), congruent with our nding in tropical regenerating dry forest. On the
other hand, 10 plant species have not been previously reported (Table 1), of
which R. gentlei, Passiora sp., and Ampelocissus acapulcensis contribute >
5% to the Citreoline Trogon´s diet. Nonetheless, T. citreolus has the potential to
consume these resources owing to the distinct fructication patterns of each
plant species within the tropical dry forest of JBPE. Randia gentlei fructies
Table 2. Mean (± SD) food resource availability for Trogon citreolus from November 2020 to April 2021 at Puerto Escondido
Botanical Garden, Oaxaca, Mexico, with parametric (one-way ANOVA) and non-parametric (Friedman) test of signicance.
Letters indicate signicantly different post hoc pairwise comparisons (Tukey-Kramer, P < 0.05) between the months.
Variables November December January February March April Signicance values
Tree species fruiting 5.1 ± 1.1a4.1 ± 1ab 2.4 ± 1.4d3.1 ± 1.4bcd 3.9 ± 1.9abc 4.8 ± 1.6aF5,59 = 17.8; P < 0.001
Trees fruiting 12.8 ± 5.3a9.4 ± 5.3ab 8.2 ± 4b9.2 ± 4.4b9 ± 6.5b11.5 ± 5.1aF5,59 = 3.4; P = 0.011
Fruit abundance index 3.7 ± 1.8bc 2.1 ± 0.8cd 1.9 ± 0.8cd 3.3 ± 1.5bc 4.7 ± 1.8ab 6.1 ± 2.4aFriedman X2
5 = 38.7,
P < 0.001

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Neotropical Biology and Conservation 19(4): 411–425 (2024), DOI: 10.3897/neotropical.19.e128529
Esmeralda Floreán-Díaz & Miguel Ángel De Labra-Hernández: Abundance and diet of Trogon citreolus
from November to April, while F. cotinifolia only fructies in January and C. en-
gleriana in February and April (Fig. 3). Of these tree species, F. cotinifolia trees
are very scarce in the study area, and their fructication period is short (about
a month). However, we observed the largest number of individuals feeding on
gs of this tree, in groups of up to seven individuals. In the preserved dry forests
of the central Mexican Pacic, the Citreoline Trogon is observed to consume
eshy, soft, and sweet fruits that are brown, red, and red-brown in color. These
fruits consist of drupes, achenes, and syconia, which are consumed whole, with
the exception of larger specimens (Pithecellobium dulce, Forchhammeria palli-
da, Spondias purpurea), which are solely consumed as the pericarp (Morán-Di-
mayuga 2002). It is plausible that the characteristics of fruits, in addition to
their availability, may exert an impact on the foraging behavior of the Citreoline
Trogon. This topic is worthy of further investigation in future studies. On the
other hand, the Citreoline trogon’s trophic niche breadth and dietary diversity
are indicative of food resources availability and fruiting patterns. These results
suggest the Citreoline Trogon follows plant phenology over time and exhibits
plasticity in the use of food resources. The capacity to exploit a more diverse
range of resources appears to be a central factor in understanding the role of
food availability on T. citreolus dynamics in tropical regenerating dry forest.
Our ndings from the Citreoline Trogon foraging behavior study correspond
with those previously reported by Eguiarte and Martínez del Rio (1985) and
Morán-Dimayuga (2002), at least during the study period (dry-season), T. citreo-
lus was almost exclusively frugivorous. However, Eguiarte and Martínez del Rio
(1985) report two observations regarding insect consumption. We did not ob-
serve T. citreolus consuming insects, as has been reported for the species from
July to September (wet-season) (Morán-Dimayuga 2002), and for other trogon
species (Pizo 2007). This may be attributed to a reduction in insect abundance
and an increased availability of fruits during the dry season in tropical dry for-
ests (Wolda 1978a, b; Bullock and Solis-Magallanes 1990), a pattern that could
occur in our study area. Other species in the genus Trogon consume insects
seasonally, particularly during periods of fruit scarcity and during the breed-
ing season when they are raising young (Riehl and Adelson 2008). Conversely,
other Trogon species include insects in their diet throughout the year (Remsen
et al. 1993). Trogon citreolus breeds during the wet season (June–October)
(Valdivia-Hoeich 2006). Therefore, we suggest evaluating this species´ diet
during the wet season to gain a complete understanding of its foraging strate-
gies in regenerating forests. Moreover, we propose assessing whether the Cit-
reoline Trogon selects food resources based on their energy content.
Relationship of food resource availability with Trogon citreolus
abundance
Although the study area is a site with 20 years of forest regeneration, the
plants exhibited phenological variation, resulting in changes in food resource
availability over time. Fruits were more abundant from February to April 2022.
This pattern of variation in fruit availability is similar to that of natural for-
ests. According to Leigh et al. (1982), fruiting peaks in tropical forests usu-
ally occur late in the dry season and early in the rainy season. Bullock and
Solis-Magallanes (1990) reported larger numbers of fruiting trees in February

420
Neotropical Biology and Conservation 19(4): 411–425 (2024), DOI: 10.3897/neotropical.19.e128529
Esmeralda Floreán-Díaz & Miguel Ángel De Labra-Hernández: Abundance and diet of Trogon citreolus
- March and July - August in a tropical dry forest in southwestern Mexico. Our
results suggest that the dynamics of tree fructication in the study area play
an important role in the abundance of T. citreolus. Specically, the highest
fructication rate and number of trogons feeding on fruits were recorded in
March and April. Levey (1988) states that the abundance of frugivorous birds
increases during the peaks of tree fructication. Berlanga-García (1991) sug-
gests that the increase in the abundance of frugivorous birds is related to the
peak fructication in Chamela, Jalisco, during March. These results support
the hypothesis that fruit availability is related to changes in the abundance of
fruit-eating birds (Levey 1988; Rey 1995; Blendinger et al. 2012). Alternatively,
the relationship between trogon abundance and tree fructication suggests
that trogons follow food resource availability in regenerating forests. During
the study period, we observed that trogons fed on a variety of plants (Table 1)
that display specic phenological patterns.
Conservation implications
At a global level, tropical forests experience high rates of deforestation due to
anthropogenic activities (Laurance 1999). In America, deforestation is espe-
cially extensive and accelerated due to changes in land use, increased agricul-
ture, and livestock (Hansen et al. 2013). When native vegetation is removed and
habitat size is reduced, fruit-eating birds are the rst to disappear (Sodhi et al.
2008). Botanical gardens play an important role in conserving local fruit-eating
birds (Li et al. 2014).
Although the JBPE only covers 16.7 hectares and is currently undergoing
a 20-year process of plant repopulation, it is a critical site for maintaining the
population dynamics of T. citreolus. As previously mentioned, the abundance
of the Citreoline Trogon is directly related to plant phenology. Therefore, the
JBPE plays a crucial role in conserving not only the Citreoline Trogon but also
the 95 species of resident and migratory birds recorded in the study area (Bo-
jorges-Baños 2012). The Universidad del Mar protects the JBPE area with sup-
port from the state government. Nonetheless, the persistent degradation of the
forest remnants situated around the botanical garden has resulted in isolation,
thereby jeopardizing the long-term survival of birdlife. We believe it is crucial to
preserve T. citreolus and other frugivorous birds to maintain the plant dynamics
of the JBPE and the surrounding forest remnants. In the JBPE, we observed oth-
er frugivorous birds feeding on fruits, including Ortalis poliocephala, Amazona
nschi, Eupsittula canicularis, Piaya cayana, Momotus mexicanus, Cyanocorax
formosus, Turdus rufopalliatus, Myiarchus cinerascens, Tyrannus vociferans,
Piranga rubra, P. ava, and Habia rubica. These birds play a crucial role in the
early stages of plant regeneration by dispersing seeds from degraded forests
(Wunderle 1997). The conservation of frugivores is essential for maintaining
the genetic ow of plants and the vegetation structure in the study area (Ter-
borgh et al. 1990; dos Santos 2006), as they are the primary seed dispersers.
The study provides fundamental information for future conservation policies
and research on frugivorous birds, and highlights the signicance of restor-
ing natural vegetation in degraded forests. In this regard, the regeneration of
forests plays a crucial role in preserving the interactions between plants and

421
Neotropical Biology and Conservation 19(4): 411–425 (2024), DOI: 10.3897/neotropical.19.e128529
Esmeralda Floreán-Díaz & Miguel Ángel De Labra-Hernández: Abundance and diet of Trogon citreolus
frugivorous birds. The analysis of interspecic interaction networks can be
used to assess the structure and function of biotic communities in regenerat-
ing forests. This approach allows for better understanding and conservation
of ecological processes in such forests (Ramos-Robles et al. 2018; Wang et al.
2023). The present vegetation conditions at JBPE present an opportunity for
future research on the ecological interactions between fruit-eating birds and
the plants that constitute a component of their diet.
Conclusion
The abundance of Trogon citreolus showed temporal variation corresponding
to uctuations in the availability of food resources throughout the study period.
Given the paucity of data regarding the population size of T. citreolus, it is im-
perative to maintain a program of monitoring the population of this species and
its habitat associations. Population size is a crucial factor in assessing species
risk and conservation status. The dietary breadth and dietary switching of the
Citreoline Trogon enable the species to adapt to uctuations in fruit availability
in regenerating forests, indicating that its foraging behavior is inuenced by the
availability of food species and abundance. Further research is required during
the wet season to obtain a comprehensive account of the Citreoline Trogon
foraging strategies in the context of regenerating forests. Our ndings highlight
the ecological importance of forest regeneration in providing food resources
for T. citreolus and other frugivorous birds. Concurrently, the presence of the
Citreoline Trogon and other frugivorous birds facilitates the recuperation of re-
generating forests by dispersing seeds during the dry season.
Acknowledgements
The authors thank the Universidad del Mar and the authorities of the Botanical
Garden for the logistical support and permits granted to carry out this study.
The Ministry of the Environment and Natural Resources of Mexico provided the
collection permit (SEMARNAT: SGPA/DGVS/9033/19). Special thanks to Santi-
ago Sinaca Colín for the support in identication of plant species, as well as to
Itzel Flores Yllescas and Azariel Tomas Arevalo Urias, for their support in eld
work. We thank Odirlei Fonseca and two anonymous reviewers for their contri-
butions to the improvement of the content of this paper.
Additional information
Conict of interest
The authors have declared that no competing interests exist.
Ethical statement
No ethical statement was reported.
Funding
This research did not receive any specic grant from funding agencies in the public,
commercial, or not-for-prot sectors.

422
Neotropical Biology and Conservation 19(4): 411–425 (2024), DOI: 10.3897/neotropical.19.e128529
Esmeralda Floreán-Díaz & Miguel Ángel De Labra-Hernández: Abundance and diet of Trogon citreolus
Author contributions
Esmeralda Floreán-Díaz: eld work, data analysis, writing, original draft, review. Miguel
Ángel De Labra-Hernández: conceptualization, eld work, data analysis, writing, original
draft, review, editing, approval.
Author ORCIDs
Esmeralda Floreán-Díaz https://orcid.org/0009-0007-3680-6339
Miguel Ángel De Labra-Hernández https://orcid.org/0000-0002-0361-4919
Data availability
All of the data that support the ndings of this study are available in the main text or
Supplementary Information.
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Supplementary material 1
List of plants recorded in the phenology transects within the regenerating
dry tropical forest of the Puerto Escondido Botanical Garden (UMAR)
Authors: Esmeralda Floreán-Díaz, Miguel Ángel De Labra-Hernández
Data type: docx
Copyright notice: This dataset is made available under the Open Database License
(http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License
(ODbL) is a license agreement intended to allow users to freely share, modify, and
use this Dataset while maintaining this same freedom for others, provided that the
original source and author(s) are credited.
Link: https://doi.org/10.3897/neotropical.19.e128529.suppl1