# Estimation of Adult Sex Ratio and Size-Related Sexual Dimorphism Based on Molecular Sex Determination in the Vulnerable La Selle Thrush, Turdus swalesi

Jean-Marry Exantus, Etienne Bezault, Christopher Cambrone, Frank Cézilly

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Jean-Marry Exantus, Etienne Bezault, Christopher Cambrone, Frank Cézilly. Estimation of Adult Sex Ratio and Size-Related Sexual Dimorphism Based on Molecular Sex Determination in the Vulnerable La Selle Thrush, Turdus swalesi. Animals, 2024, 14 (6), pp.842. 10.3390/ani14060842. [https://doi.org/10.3390/ani14060842](https://doi.org/10.3390/ani14060842)

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Article

# Estimation of Adult Sex Ratio and Size-Related Sexual Dimorphism Based on Molecular Sex Determination in the Vulnerable La Selle Thrush, *Turdus swalesi*

Jean-Marry Exantus<fnref n="1" />,<fnref n="2" />*, Etienne Bezault <fnref n="1" />,<fnref n="2" /> ID, Christopher Cambrone <fnref n="1" />,<fnref n="2" /> ID and Frank Cézilly <fnref n="1" /> ID

**Simple Summary:** This study assessed the adult sex ratio and sexual dimorphism in body size in the vulnerable La Selle Thrush, *Turdus swalesi*, over a 26-month period, in Haiti. We found that the overall adult sex ratio was significantly male-biased. However, this was only true during the non-breeding season, suggesting that males may show more site tenacity than females, although true differences in adult survival between males and females cannot be ruled out. We observed a slight, albeit significant, sexual dimorphism in size, with males having, on average, both a longer wing chord and a longer tail than females. Tail length was the best predictor of sex in a logistic regression model, with about 80% of individuals being correctly assigned to their actual sex. Understanding the causes and consequences of the observed male-biased sex ratio might be important for the conservation of the La Selle Thrush, particularly in the face of ongoing severe deforestation in Haiti.

**Abstract:** Sex-determination is of particular importance in avian ecology and conservation. However, many bird species show no conspicuous sexual dimorphism, such as the La Selle Thrush, *Turdus swalesi*, a vulnerable species endemic to Hispaniola. We captured individuals in southeastern Haiti, in 2019–2022. For each one, we collected contour feathers or blood samples for molecular sex identification based on the CHD-1 gene. In addition, we took body measurements of several captured individuals and recorded their weight. Out of a total of 65 birds, 45 were identified as males and 20 as females, indicative of a significantly male-biased sex ratio. However, analyses of first captures showed that the sex ratio at our study site was male-biased only outside of the breeding season, suggesting that females may disperse at that time while males remain on their territories. Sexual dimorphism was limited to wing chord length and tail length, with males being larger than females. Tail length was the best predictor of sex in a logistic regression model and correctly classified about 80% of individuals as male or female. We discuss our results in relation to previous studies of sex ratio and sexual dimorphism in turdid species and address their relevance for the conservation of avian species in one of the major protected forest areas in Haiti.

**Keywords:** CHD-1 gene; conservation; Haiti; Hispaniola; sex ratio; tail length; *Turdus swalesi*

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**Citation:** Exantus, J.-M.; Bezault, E.; Cambrone, C.; Cézilly, F. Estimation of Adult Sex Ratio and Size-Related Sexual Dimorphism Based on Molecular Sex Determination in the Vulnerable La Selle Thrush, *Turdus swalesi*. *Animals* **2024**, *14*, 842. https://doi.org/10.3390/ani14060842

Academic Editor: Pietro Parma

Received: 26 June 2023

Revised: 1 August 2023

Accepted: 8 August 2023

Published: 8 March 2024

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**Copyright:** © 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

## 1. Introduction

Although sexual dimorphism can be particularly conspicuous in some bird species, particularly in polygynous ones [1], it can be quite subtle in others, making the distinction between males and females through direct visual observation particularly difficult, if not impossible. Sex identification of sexually monomorphic bird species is, however, of particular importance to understand their evolutionary ecology [2], investigate sex-related differences in behavior [3,4], estimate demographic parameters [5,6], and is often relevant

<footnote n="1">¹ Caribaea Initiative, c/o Université des Antilles, Campus de Fouillole, F-97110 Pointe-à-Pitre, CEDEX, France; etienne.bezault@univ-antilles.fr (E.B.); christopher.cambrone@caribaea.org (C.C.); frank.cezilly@u-bourgogne.fr (F.C.)</footnote>

<footnote n="2">² UMR BOREA, CNRS 8067, MNHN, IRD, Sorbonne Université, Université Caen Normandie, Université des Antilles, Campus de Fouillole, F-97110 Pointe-à-Pitre, CEDEX, France</footnote>

<footnote>* Correspondence: jeanmary.exantus@yahoo.fr</footnote>
to conservation and management [7–9]. In particular, sex identification is crucial for the estimation of the adult sex ratio (the proportion of males and females in the adult population) in monomorphic bird species. The adult sex ratio is a demographic trait of a population that depends on sex ratios at conception and birth, and is then modified by sex differences in rates of maturation, mortality, dispersal, and immigration [10]. The adult sex ratio is an important characteristic of animal populations [11,12], and has direct relevance to behavioral ecology, evolution, and conservation [13,14]. In particular, deviations from a balanced adult sex ratio (i.e., an equal proportion of males and females in the adult population), can have negative consequences for individual fitness and population viability in birds [15,16].

Various methods have been used to provide accurate sexual determination in monomorphic avian species. Whereas earlier studies relied on anatomical investigations [17] or sex-specific behaviors [18,19], the advent of molecular techniques has provided a standardized and reliable method to sex monomorphic bird species based on sex chromosome-specific markers [20,21]. Avian DNA can indeed be obtained relatively easily from non-invasive (eggshell swab, shed feather, and feces), nondestructive (plucked feather and buccal swab), or invasive (blood) methods [22–27]. Molecular sexing is now routinely used to assess the extent of sexual dimorphism in body size and/or variation in sex ratio in monomorphic avian species [28–34].

The La Selle Thrush, *Turdus swalesi*, is a sexually monomorphic passerine endemic from Hispaniola. This large-bodied turdid species has black, rufous, and white plumage, and a yellow to orange bill and eye-ring [35]. The species was originally described about one century ago from the "Massif de La Selle", in southeastern Haiti [36]. It was only known from there until individuals were observed in the Sierra de Bahoruco (which is the eastern extension of the La Selle ridge into the Dominican Republic) in 1971, and then in the Sierra de Neiba and the Cordillera Central in 1975 [37,38]. Based on lighter back plumage, populations from the Sierra de Neiba and Cordillera Central were later considered as distinct subspecies, *T. swalesi dodae* [39]. Although the species is currently classified as vulnerable in the IUCN Red List [40], very limited information is available about its ecology, behavior, and population dynamics. The species is at risk, given its restricted distribution area, and is threatened by habitat loss and fragmentation, particularly due to intense deforestation in Haiti [41,42], and, possibly, exotic mammal predators (J.M. Exantus unpubl. data).

Here, we report new and original data on the La Selle Thrush, collected as part of a long-term capture-mark-recapture program of the La Selle ridge population in Haiti. Our objective was to assess the adult sex ratio and the extent of sexual dimorphism in adult body size in this poorly studied species. To that end, we captured and measured individuals from which we collected feathers or blood samples as sources of DNA. We then used the accurate DNA-based test method, PCR amplification, to sex the captured individuals [21,43–45]. Based on previous evidence for seasonal variation in the sex ratio of turdid species in relation to breeding activity in both tropical and temperate areas [46,47], we expected differences in the adult sex ratio between the breeding and non-breeding seasons. We discuss our results in relation to variation in both sex ratio and the extent of sexual dimorphism in natural populations of other turdid species, and to conservation issues.

**2. Materials and Methods**

**2.1. Study Site and Data Collection**

Mist-netting of La Selle Thrushes took place in the locality of "Tête Opaque" (18°20.928' N, 072°14.347' W), within the Parc La Visite (Figure 1), located in the La Selle ridge, at an altitude varying between 2146 and 2260 m. The area is located to the north of the first municipal district of Baie d'Orange, commune of Belle Anse, in Haiti's Southeastern district.
<figure><img src="image_5.png" /><figcaption>**Figure 1.** Location of study area “Tête Opaque” within the limits of Parc La Visite, southeastern Haiti. © 2023 Microsoft Corporation, accessed on 24 July 2023.</figcaption></figure>

We carried out 13 consecutive field surveys at our field station in Parc la Visite between December 2019 and January 2022. The duration of field sessions varied from 3 to 15 days (median = 12.5), partly depending on weather conditions, while the duration of intervals between consecutive field sessions varied between 20 and 68 days (median = 40), except for an interruption from 26 February to 26 September in 2020 due to the COVID pandemic and safety issues in Haiti. The breeding season of the La Selle Thrush lasts from April to the end of July [48–50], J.M. Exantus pers. obs., such that three field sessions took place during the 2021 breeding season, whereas all other sessions took place outside of the breeding season.

On each session, we used footpaths varying between 800 and 1000 m in length and pre-existing openings in vegetation (abandoned agricultural plots) created by humans to deploy mist nets (Ecotone®, Gdynia, Poland, 6 × 3 m, 19 mm mesh, most suitable for the La Selle Thrush and Ecotone® 12 × 3 m, 30 mm mesh) at regular intervals. The total length of mist nets varied progressively from 12 m to 96 m from the first to the last session. The position of mist nets varied between sessions depending on interferences with agricultural activities by local people, such that the overall study area covered about 268 ha (see Figure 1), as determined by GPS (Garmin®, Olathe, KA, U.S.A., Montana 680) coordinates. We regularly broadcasted the call of the la Selle Thrush to attract individuals to the mist nets and increase capture rates [51]. Mist nets were checked every 25 minutes and on hearing birds screaming loudly after being captured, or to ward off free-ranging animals (cattle, sheep, horses, and pigs) that ventured too close to the mist nets. In case of rain or strong wind, we temporarily closed or did not operate the mist nets.

Each captured individual was ringed with a unique combination of an aluminum leg band engraved with an alphanumeric reference code and 1–2 colored plastic rings. We measured tarsus length (TarL), tarsus width (TarW), bill width at nostrils (BWN), bill width at the tip (BWT), bill length to the base of the skull (BL), and head length including bill (HBL) using a dial caliper with a 0.1 mm accuracy. In addition, we measured wing chord length (WCL) and tail length (TaiL) to the nearest millimeter, using a metal ruler and a flat ruler with a stop at zero, respectively. We measured the weight (W) of individuals to the nearest gram using a Pesola 500 g spring scale. All measurements were taken according to recommendations provided by the Centre de Recherche sur la Biologie des Populations d'Oiseaux [52] and the North American Banding Council [53].
We collected two different tissues as their effectiveness as source of high-quality DNA for molecular analyses may vary between bird species [26]. We first used a non-destructive method relying on contour feather sampling [22–25]. We collected three to five small contour feathers from each captured individual and placed them in envelopes with “silica gel” moisture absorber for dry storage. Using a more invasive method, we collected ~15 µL blood samples from the brachial vein from a subsample of individuals [54,55]. The collected blood samples were preserved in ethyl alcohol of 99.99% volume purity. Blood samples were stored in the laboratory at –20 °C for 18 months until DNA extraction [26].

The entire handling process of each captured bird, including blood and/or feather sampling and, when time allowed, biometric measurements, took an average of 13 minutes per bird. Complete processing was not possible for birds that were captured late in the afternoon. Such birds were quickly released immediately after ringing and feather collection, without taking biometric measurements or collecting a blood sample.

## 2.2. *Molecular Analyses*

Following the protocol developed by Cambrone et al. [26], we used a commercial DNeasy Blood and tissue kit (Qiagen Inc., Valencia, CA, USA) to extract DNA from blood samples. For DNA extraction from collected feather samples, we used calamus tips and blood clots and/or barbs from feathers [56,57]. Samples were then digested overnight by adding 30 µL of 1M dithiothreitol (DTT) to the commercial kit lysis solution, including proteinase K [58]. The same PCR (polymerase chain reaction) protocol was used for DNA samples from blood and feathers to sex individuals using primers developed by Fridolfsson & Ellegren [59], while adding 1.50 µL of Bovine Serum Albumin, following the PCR protocol developed by Cambrone et al. [26]. We identified sex using size variation of introns of the Chromo-Helicase-DNA binding protein genes (CHD1-Z and CHD1-W), using 2550F/2718R primer pair, standard PCR conditions, and agarose gel (3%) electrophoresis [26,59]. Intron size variation was easily scored, with CHD1-W = 450 pb and CHD1-Z = 750 pb, using a 100 pb ladder (Nippon Genetics Co., Düren, Germany). For a few individuals for which sex identification was ambiguous on the first PCR, we conducted two additional PCR and electrophoresis.

## 2.3. *Statistical Analysis*

We first assessed deviation from a balanced adult sex ratio among all sexed individuals using a binomial test. In addition, we compared the relative proportions of first-captured males and females during the breeding and non-breeding seasons using a Fisher's exact test.

We relied on Shapiro-Wilk tests to assess the normality of biometric measurements. As most of them were not normally distributed, we used non-parametric tests to assess correlations between biometric measurements and differences between sexes. We then excluded measurements that were significantly correlated between themselves (*p* < 0.05) to build logistic regression models and predict the sex of individuals. We favored the use of logistic regressions over a discriminant analysis given the relatively small sample size [60].

We compared the fit of logistic regression models using difference in the small-sample corrected Akaike Information Criterion, AICc, and considered models with Δ AICc < 4 as equally informative [61]. We analyzed all data using the package “stats” in the R software, version 4.2.2 [62], and considered the results significant at the 0.05 level.

## 3. Results

Overall, we obtained blood from 45 individuals and relied on feathers as a source of DNA for 21 additional birds. DNA extraction was successful for all individuals, but one for which we failed to extract DNA of high enough quality from contour feathers. Out of the 65 remaining individuals, 45 were identified as males and 20 as females (binomial test, *p* = 0.0013). The proportion of individuals identified as males or females was independent of the tissue (blood of feathers) that was used as a source of DNA (Chi-square test,
$X^2 = 0.462$, d.f. = 1, $p = 0.4968$). However, there was a significant difference in the proportions of first-captured males and females between the breeding and the non-breeding seasons (Table 1; Fisher's exact test, $p = 0.0034$).

<table><caption>**Table 1.** Proportions of first-captured males and females according to season.</caption><thead><tr><th></th><th>Males</th><th>Females</th><th>Percentage of Females</th></tr></thead><tbody><tr><td>Breeding season</td><td>2</td><td>7</td><td>77.78%</td></tr><tr><td>Non-breeding season</td><td>43</td><td>14</td><td>24.56%</td></tr></tbody></table>

### Sexual Size Differences in the La Selle Thrush

Biometric measurements were available for 43 individuals of known sex (29 males and 14 females). Only tarsus length and weight were normally distributed (Shapiro-Wilk test, $W = 0.98, p = 0.4887$ and $W = 0.96, p = 0.1723$, respectively), whereas all other measured traits did not follow a normal distribution ($0.76 \le W \le 0.94, 0.0289 \le p \le 0.0001$). Table 2 shows values for biometric traits according to assigned sex and corresponding non-parametric statistical tests for significant differences. Males and females differed significantly only for wing chord length and tail length. However, wing chord length and tail length were positively correlated among individuals (Spearman rank correlation coefficient, $r_s = 0.44$, $n = 43, p = 0.0035$).

<table><caption>**Table 2.** Median values, interquartile range (IQR), minimal (Min), and maximum (Max) values of body size (mm) and weight (g) according to assigned sex and corresponding statistical tests (Mann-Whitney test for two independent samples). Significant differences are highlighted in bold.</caption><thead><tr><th rowspan="2"></th><th colspan="5">Males (n = 29)</th><th colspan="5">Females (n = 14)</th></tr><tr><th>Median Value</th><th>IQR</th><th>Min</th><th>Max</th><th>Median Value</th><th>IQR</th><th>Min</th><th>Max</th><th>z</th><th>p</th></tr></thead><tbody><tr><td>TarL</td><td>46.3</td><td>44.3-48.0</td><td>40.3</td><td>52.4</td><td>46.1</td><td>43.8-49.3</td><td>42</td><td>55.5</td><td>0.29</td><td>0.7755</td></tr><tr><td>TarW</td><td>33</td><td>33.0-33.6</td><td>31</td><td>34</td><td>33</td><td>33.0-33.0</td><td>31</td><td>34</td><td>1.62</td><td>0.1031</td></tr><tr><td>BWN</td><td>7.2</td><td>6.8-8.0</td><td>5.4</td><td>10.4</td><td>7.4</td><td>6.9-7.9</td><td>6.1</td><td>8.5</td><td>0.27</td><td>0.7849</td></tr><tr><td>BWT</td><td>2.2</td><td>2.0-2.4</td><td>2</td><td>2.9</td><td>2.2</td><td>2.1-2.4</td><td>2</td><td>2.9</td><td>0.52</td><td>0.606</td></tr><tr><td>BL</td><td>21.8</td><td>20.2-23.4</td><td>18.6</td><td>27</td><td>22.4</td><td>20.1-23.9</td><td>19.5</td><td>27.3</td><td>0.43</td><td>0.6686</td></tr><tr><td>HBL</td><td>56.9</td><td>55.1-58.5</td><td>50</td><td>60</td><td>57</td><td>55.5-58.7</td><td>50.5</td><td>61.4</td><td>0.31</td><td>0.7557</td></tr><tr><td>WCL</td><td>128</td><td>126-130</td><td>120</td><td>132</td><td>124</td><td>120-130</td><td>120</td><td>130</td><td>2.38</td><td><strong>0.0173</strong></td></tr><tr><td>TaiL</td><td>110</td><td>105-110</td><td>99</td><td>120</td><td>100</td><td>98-109</td><td>90</td><td>110</td><td>3.11</td><td><strong>0.0019</strong></td></tr><tr><td>W</td><td>120</td><td>110-125</td><td>98</td><td>135</td><td>120</td><td>110-120</td><td>90</td><td>150</td><td>0.36</td><td>0.707</td></tr></tbody></table>

We, therefore, used them separately to predict the sex of individuals in logistic regression models with sex as a binomial variable. Table 3 shows the four best models retained by model selection. In terms of accuracy of sex assignment, the best model with only tail length correctly classified 81.4% of individuals, with no difference between sexes (Fisher's exact test on proportions of correctly and incorrectly classified individuals according to sex, $p = 0.4038$). Based on this model, the probability that a bird is a male can be calculated following the following equation: $p$ (male) = $1/1 + e^{-(23+0.23(tail length))}$, with $0 \le p$ (male) $\le 1$. The higher the $p$ (male) value is, the more likely the individual is a male. The second-best model including tarsus width in addition to tail length provided exactly the same percentage of correct sex assignment.
<table><caption>**Table 3.** Parameters of the best four logistic regression models showing the association between body measurements and sex in the La Selle Thrush (n = 43). Response variable was the sex of individuals and explanatory variables were four different combinations of measurements.</caption><thead><tr><th rowspan="2">Independent variables</th><th colspan="2">Goodness of Fit</th><th colspan="2">Model Selection</th></tr><tr><th>χ<sup>2</sup></th><th>p</th><th>AICc</th><th>Δ<sub>AICc</sub></th></tr></thead><tbody><tr><td>Tail length</td><td>12.15</td><td>0.0005</td><td>46.42</td><td>-</td></tr><tr><td>Tail length and tarsus width</td><td>14.07</td><td>0.0009</td><td>46.81</td><td>0.41</td></tr><tr><td>Wing chord length and tarsus width</td><td>10.64</td><td>0.0049</td><td>50.24</td><td>3.82</td></tr><tr><td>Wing chord length</td><td>7.16</td><td>0.0075</td><td>51.41</td><td>4.99</td></tr></tbody></table>

## 4. Discussion

Previous studies on other turdid species relied exclusively on blood samples to obtain DNA for molecular sexing [11,46,47,63–65]. Here, we used both blood and contour feathers with equal success to assign a sex to individuals. We found no significant difference in the sex ratio of birds sexed with DNA extracted from feathers or blood. As plucking of contour feathers might be regarded as a less intrusive and less harmful method to obtain DNA [25,66], we recommend giving priority to this technique when biological samples are only needed for sex determination, especially for passerine species of conservation interest.

The strongly male-biased overall adult sex ratio observed in our study population deserves particular attention. On the one hand, it might be a direct consequence of using playback around mist nets to increase capture efficiency, as previously advanced to explain male-biased sex ratio among captured individuals of another Caribbean-endemic thrush species [67]. Indeed, males of some passerine species tend to be more strongly attracted by playbacks than females [68]. On the other hand, Chin et al. [69] found no difference between sexes in attraction towards audio lures in wintering Wood Thrushes, *Hylocichla mustelina*. In addition, we captured or recaptured significantly more male individuals than females during the non-breeding season, whereas, although the sample size was limited, there was no difference in the proportions of male and female La Selle Thrushes during the breeding season. This seasonal pattern of variation in adult sex ratio is similar to what was reported by Ritter et al. [46] for the White-necked Thrush, *Turdus albicollis*, in southeastern Brazil. One possibility, then, is that the two sexes differ in their strategy outside of the breeding season with males staying on their territories while females disperse out of the area [70]. Males may benefit from remaining on their territories to maintain ownership, whereas females may benefit from dispersing in various ways. First, seasonal variation in male–female competition for food resources may favor female dispersal if males are the most competitive sex, particularly during the dry season when food availability is reduced [71,72]. Second, females of monogamous bird species may disperse during the non-breeding season to assess alternative breeding opportunities at other sites [73,74]. Radio-tracking of individuals of both sexes (see Aubry et al., [75]) might be useful in the future to document seasonal variation in movements and home ranges of the species. Third, a higher proportion of males than females has been previously reported in several tropical *Turdus* species [11,46,64,76]. The overall male-biased adult sex ratio observed in the present study could thus be a particular feature of the *Turdus* species in tropical forests if, for instance, adult survival rate tends to differ between the two sexes [70,77]. Such differences in adult survival between the sexes might be related to the estimation of sex-specific adult survival in the La Selle Thrush using capture-mark-recapture data [78], and further investigations are thus needed to better understand variation in the adult sex ratio of this vulnerable species.

Overall, body size and weight overlapped largely between male and female La Selle Thrushes. However, we evidenced a subtle, albeit significant, sexual dimorphism in body size in the La Selle Thrush, with median tail length being about 10% longer in males compared to females, and median wing length being about 3.5% longer, with both characters
being positively correlated between themselves. Similarly, several studies found that wing
length was sexually dimorphic and longer in males of thrush species [11,46,47,63–65,79],
whereas tail length was seldom included in the analysis of sexual dimorphism in turdid
species (however, see Frey et al. [79]). Although direct evidence is lacking for the La Selle
Thrush, wing flicking and tail raising have been observed during ritualized aggressive
encounters in other thrush species [80,81], such that the observed sexual dimorphism may
indicate potential male social dominance over females.

The percentage of correct sex assignment using a regression logistic model based on tail length was about 80% and compares with other studies of turdid species using logistic regression models or discriminant analysis to determine sex from morphometric measurements [47,65]. However, sex identification of La Selle Thrushes in the field solely based on morphometrics appears poorly reliable, with an error rate of about 20%, thus justifying the use of molecular tools to ascertain the sex of individuals, particularly for future studies investigating demographic parameters and behavior.

**5. Conclusions**

Our study provides new perspectives for a long-term survey of the vulnerable La Selle Thrush. First, the collection of contour feathers appears to be a reliable method to obtain DNA of enough quality for molecular sexing. Future investigations should check to what extent DNA extracted from feathers can also be used for the analysis of genetic structure, using both mitochondrial and nuclear markers. This is of prime importance to assess the overall degree of genetic diversity at the species level and assess the actual extent of genetic differentiation between the two recognized subspecies. Second, the causes and consequences of the observed male-biased sex ratio should be addressed using a larger sample of individuals covering a larger part of the species distribution area. In particular, capture-mark-recapture analyses may prove useful in estimating potential sex-related differences in survival and probability of capture in pre-fledging, juvenile, and adult individuals [6,82].

Continued monitoring of the La Selle ridge population of the La Selle Thrush is also
of high importance for avian conservation in Haiti as the species demographic trends
might be representative of that of several other forest-dependent avian species known to
occur in Parc La Visite, including several endemic ones [83,84], in the face of persistent
environmental degradation. In that respect, assessing variation in the adult sex ratio
among local avian species in relation to their degree of forest dependency might provide
a clue to the consequences of deforestation for local bird species, as deviation from a
balanced sex ratio tends to be more severe in populations of threatened avian species than
in non-threatened ones [85]. Although the ability to conduct ornithological research in
Haiti remains currently limited due to political instability, lack of local scientific expertise,
and limited access to equipment and funding [86], the present study and a few recent
ones [87,88] raise some hope for the future.

**Author Contributions:** J.-M.E. was involved in study design and methodology, data collection, part of statistical analysis, and writing up of the article. E.B. was involved in supervision and conducted the genetics analyses; C.C. contributed to genetics analyses and writing up of the article; F.C. was involved in study design, supervision, project administration, statistical analysis and writing up of the article. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the Caribaea Initiative (grant numbers: 201703A_JME; 201901A_JME); the Fokal Foundation (grant number: 1960-22); and the Rufford Foundation (grant number: 36175-1).

**Institutional Review Board Statement:** Access to the protected area, "Parc National La Visiste", capture and handling of the species, and collection of biological samples (blood and feathers) were carried out with the agreement of the Direction of Biodiversity, Haitian Ministry of the Environment. The study complied with relevant laws and guidelines for the capture and banding of birds, as well as rules for collecting genetic data.
**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** The data that support the findings of this study are available from the corresponding author, [JME], upon reasonable request.

**Acknowledgments:** We are grateful to Pharlain Davance and Wilson Aubourg for assistance in field work and to our field guides, Lionel Raymond, Julsaine Raymond, and Noula Auguste, for help in data collection. We thank the Ministry of Environment of the Republic of Haiti, and especially Michelet Louis, for granting us permits to work in protected areas and capture and process birds. We thank the administration of the Seguin Foundation for their help in setting up the field work. We are grateful to Maryne Romuald for assistance in genetic analyses and to Bruno Faivre for kindly providing color leg bands. The authors are grateful to Caribaea Initiative, the Fokal Foundation, and the Rufford Foundation for their moral, technical, and financial support. We thank three anonymous referees for their valuable and constructive comments.

**Conflicts of Interest:** The authors report no competing interest or personal relationships that could have appeared to influence the work reported in this paper.

## References

1. Dunn, P.O.; Whittingham, L.A.; Pitcher, T.E. Mating systems, sperm competition, and the evolution of sexual dimorphism in birds. *Evolution* **2001**, *55*, 161–175.

2. Dobreva, M.P.; Lynton-Jenkins, J.G.; Chaves, J.A.; Tokita, M.; Bonneaud, C.; Abzhanov, A. Sex identification in embryos and adults of Darwin's Finches. *PLoS ONE* **2021**, *16*, e0237687. [CrossRef] [PubMed]

3. Lewis, S.; Schreiber, E.A.; Daunt, F.; Schenk, G.A.; Orr, K.; Adams, A.; Wanless, S.; Hamer, K.C. Sex-specific foraging behaviour in tropical boobies: Does size matter? *Ibis* **2005**, *147*, 408–414. [CrossRef]

4. Quinard, A.; Cézilly, F. Sex roles during conspecific territorial defence in the Zenaida dove, *Zenaida aurita*. *Anim. Behav.* **2012**, *83*, 47–54.

5. Breitwisch, R. Mortality patterns, sex ratios, and parental investment in monogamous birds. In *Current Ornithology*; Power, D.M., Ed.; Springer: Boston, MA, USA, 1989; pp. 1–50.

6. Tavecchia, G.; Pradel, R.; Boy, V.; Johnson, A.R.; Cézilly, F. Sex- and age-related variation in survival and cost of first reproduction in Greater flamingos. *Ecology* **2001**, *82*, 165–174. [CrossRef]

7. Millar, C.D.; Reed, C.E.M.; Halverson, J.L.; Lambert, D.M. Captive management and molecular sexing of endangered avian species: An application to the Black stilt *Himantopus novaezelandiae* and hybrids. *Biol. Conserv.* **1997**, *82*, 81–86.

8. Bermúdez-Humarán, L.G.; García-García, A.; Leal-Garza, C.H.; Riojas-Valdes, V.M.; Jaramillo-Rangel, G.; Montes-de-Oca-Luna, R. Molecular sexing of monomorphic endangered Ara birds. *J. Exp. Zool.* **2002**, *292*, 677–680. [CrossRef]

9. Boulord, A.; Yang, X.-T.; Wang, T.-H.; Wang, X.-M.; Jiguet, F. Determining the sex of Reed Parrotbills *Paradoxornis heudei* from biometrics and variations in the estimated sex ratio, Chongming Dongtan Nature Reserve, China. *Zool. Stud.* **2011**, *50*, 560–565.

10. Veran, S.; Beissinger, S.R. Demographic origins of skewed operational and adult sex ratios: Perturbation analyses of two-sex models. *Ecol. Lett.* **2009**, *12*, 129–143. [CrossRef] [PubMed]

11. Lens, L.; Galbusera, P.; Brooks, T.; Waiyaki, E.; Schenck, T. Highly skewed sex ratios in the critically endangered Taita thrush as revealed by CHD genes. *Biodivers. Conserv.* **1998**, *7*, 869–873. [CrossRef]

12. Rodrigues, J.F.M.; Coelho, M.T.P. Differences in movement pattern and detectability between males and females influence how common sampling methods estimate sex ratio. *PLoS ONE* **2016**, *11*, e0159736. [CrossRef]

13. Amrhein, V.; Scaar, B.; Baumann, M.; Minéry, N.; Binnert, J.-P.; Korner-Nievergelt, F. Estimating adult sex ratios from bird mist netting data: Mist netting results on adult sex ratios. *Methods Ecol. Evol.* **2012**, *3*, 713–720. [CrossRef]

14. VanderWerf, E.A.; Crampton, L.H.; Diegmann, J.S.; Atkinson, C.T.; Leonard, D.L. Survival estimates of wild and captive-bred released Puaiohi, an endangered Hawaiian thrush. *Condor* **2014**, *116*, 609–618.

15. Grüebler, M.; Schuler, H.; Müller, M.; Spaar, R.; Horch, P.; Naef-Daenzer, B. Female biased mortality caused by anthropogenic nest loss contributes to population decline and adult sex ratio of a meadow bird. *Biol. Conserv.* **2008**, *141*, 3040–3049.

16. Heinsohn, R.; Olah, G.; Webb, M.; Peakall, R.; Stojanovic, D. Sex ratio bias and shared paternity reduce individual fitness and population viability in a critically endangered parrot. *J. Anim. Ecol.* **2019**, *88*, 502–510. [PubMed]

17. Risser, A.C. A technique for performing laparotomy on small birds. *Condor* **1971**, *73*, 376–379. [CrossRef]

18. Fletcher, K.L.; Hamer, K.C. Sexing Terns Using Biometrics: The advantage of within-pair comparisons. *Bird Study* **2003**, *50*, 78–83. [CrossRef]

19. Daniel, C.; Millar, C.D.; Ismar, S.M.H.; Stephenson, B.M.; Hauber, M.E.; Daniel, C.; Millar, C.D.; Ismar, S.M.H.; Stephenson, B.M.; Hauber, M.E. Evaluating molecular and behavioural sexing methods for the Australasian gannet (*Morus serrator*). *Aust. J. Zool.* **2007**, *55*, 377–382. [CrossRef]

20. Griffiths, R.; Daan, S.; Dijkstra, C. Sex identification in birds using two CHD genes. *Proc. R. Soc. B Biol. Sci.* **1996**, *263*, 1251–1256.

21. Ellegren, H.; Sheldon, B.C. New tools for sex identification and the study of sex allocation in birds. *Trends Ecol. Evol.* **1997**, *12*, 255–259.
22. Dai, Y.; Lin, Q.; Fang, W.; Zhou, X.; Chen, X. Noninvasive and nondestructive sampling for avian microsatellite genotyping: A case study on the vulnerable Chinese egret (*Egretta eulophotes*). *Avian Res.* **2015**, *6*, 24. [CrossRef]

23. Maurer, G.; Beck, N.; Double, M.C. A 'feather-trap' for collecting DNA samples from birds. *Mol. Ecol. Resour.* **2010**, *10*, 129–134. [CrossRef]

24. Yannic, G.; Sermier, R.; Aebischer, A.; Gavrilo, M.V.; Gilg, O.; Miljeteig, C.; Sabard, B.; Strøm, H.; Pouivé, E.; Broquet, T. Description of microsatellite markers and genotyping performances using feathers and buccal swabs for the Ivory gull (*Pagophila eburnea*): Feather and swab genotyping performances. *Mol. Ecol. Resour.* **2011**, *11*, 877–889. [CrossRef]

25. Costantini, V.; Guaricci, A.C.; Laricchiuta, P.; Rausa, F.; Lacalandra, G.M. DNA sexing in Humboldt penguins (*Spheniscus humboldti*) from feather samples. *Anim. Reprod. Sci.* **2008**, *106*, 162–167. [CrossRef]

26. Cambrone, C.; Motreuil, S.; Reyes, F.O.; Landestoy, M.A.; Cézilly, F.; Bezault, E. Obtaining DNA samples from sensitive and endangered bird species: A comparison of saliva and blood samples. *Ardeola* **2022**, *69*, 311–326. [CrossRef]

27. Taberlet, P.; Waits, L.P.; Luikart, G. Noninvasive genetic sampling: Look before you leap. *Trends Ecol. Evol.* **1999**, *14*, 323–327. [CrossRef] [PubMed]

28. Landers, T.J.; Dennis, T.E.; Hauber, M.E. Gender assignment of Westland petrels (*Procellaria westlandica*) using linear discriminant function analysis. *Wilson J. Ornithol.* **2011**, *123*, 720–725. [CrossRef]

29. Ayala-Pérez, V.; Carmona, R.; Baker, A.J.; Farmer, A.H.; Uraga, R.F.; Arce, N. Phenotypic sexing of Marbled godwits (*Limosa fedoa*): A molecular validation. *Waterbirds* **2013**, *36*, 418–425. [CrossRef]

30. Jakubas, D.; Wojczulanis-Jakubas, K.; Kulaszewicz, I. Factors affecting haematological variables and body mass of Reed warblers (*Acrocephalus scirpaceus*) and Sedge warblers (*A. schoenobaenus*). *Ann. Zool. Fenn.* **2013**, *50*, 146–157. [CrossRef]

31. Montalvo, A.E.; Powell, R.A.; MACdonald, M.D.; Ransom, D., Jr.; Lopez, R.R. A morphometric sex determination model for adult Greater roadrunners (*Geococcyx californianus*). *Wildl. Soc. Bull.* **2014**, *38*, 837–841. [CrossRef]

32. Nana, E.D.; Munclinger, P.; Ferenc, M.; Sedláček, O.; Albrecht, T.; Hořák, D. Sexing monomorphic western mountain greenbuls on Mount Cameroon using morphometric measurements. *Afr. Zool.* **2014**, *49*, 247–252. [CrossRef]

33. Yannic, G.; Broquet, T.; Strøm, H.; Aebischer, A.; Dufresnes, C.; Gavrilo, M.V.; Grant Gilchrist, H.; Mallory, M.L.; Guy Morrison, R.I.; Sabard, B.; et al. Genetic and morphological sex identification methods reveal a male-biased sex ratio in the Ivory gull *Pagophila eburnea*. *J. Ornithol.* **2016**, *157*, 861–873. [CrossRef]

34. Petracci, P.F.; Burgos, J.M.; López, G.C.; Delhey, K.; Carrizo, M.; Sarria, R.; Sotelo, M.; Somoza, G.M.; Sala, L.F.L. Field sexing Olrog's gull (*Larus atlanticus*) using morphometry. *Waterbirds* **2018**, *41*, 411–416. [CrossRef]

35. Kirwan, G.M.; Levesque, A.; Oberle, M.; Sharpe, C.J. *Birds of the West Indies: Lynx and BridLife International Field Guides*; Lynx Edicions: Barcelona, Spain, 2019.

36. Wetmore, A. A thrush new to science from Haiti. *Proc. Biol. Soc. Wash.* **1927**, *40*, 55–56.

37. Stockton de Dod, A. *Aves de República Dominicana*; Museo Nacional de Historia Natural: Santo Domingo, Dominican Republic, 1978.

38. Stockton de Dod, A. *Endangered and Endemic Birds of the Dominican Republic*; Cypress House: Fort Bragg, CA, USA, 1992.

39. Graves, G.R.; Olson, S.L. A new subspecies of *Turdus swalesi* (aves: Passeriformes: Muscicapidae) from the Dominican Republic. *Proc. Biol. Soc. Wash.* **1986**, *99*, 580–583.

40. Birdlife International. *Turdus swalesi*. The IUCN Red List of Threatened Species 2021: E.T22708955A179861776. 2021. Available online: http://nabanding.net/wp-content/uploads/2012/04/Passereaux-et-de-Pass%C3%A9riformes.pdf (accessed on 16 June 2023).

41. Dolisca, F.; McDaniel, J.M.; Teeter, L.D. Farmers' perceptions towards forests: A case study from Haiti. *For. Policy Econ.* **2007**, *9*, 704–712. [CrossRef]

42. Hedges, S.B.; Cohen, W.B.; Timyan, J.; Yang, Z. Haiti's biodiversity threatened by nearly complete loss of primary forest. *Proc. Natl. Acad. Sci. USA* **2018**, *115*, 11850–11855. [CrossRef] [PubMed]

43. Ellegren, H.; Gustafsson, L.; Sheldon, B.C. Sex ratio adjustment in relation to paternal attractiveness in a wild bird population. *Proc. Natl. Acad. Sci. USA* **1996**, *93*, 11723–11728. [CrossRef]

44. Tomasulo, A.M.; Del Lama, S.N.; Rocha, C.D. Molecular method of sexing waterbirds without DNA extraction. *Waterbirds* **2002**, *25*, 245–248. [CrossRef]

45. Huynen, L.; Millar, C.D.; Lambert, D.M. A DNA test to sex ratite birds. *Mol. Ecol.* **2002**, *11*, 851–856. [CrossRef]

46. Ritter, P.; Miyaki, C.Y.; de Leon, A.P.; Alves, M.A.S. Sex determination using CHD-1 gene and sexual dimorphism in the White-necked thrush (*Turdus albicollis*) in the atlantic forest at Ilha Grande, Rio de Janeiro, southeastern Brazil. *Ornitol. Neotrop.* **2003**, *14*, 433–440.

47. Redlisiak, M.; Mazur, A.; Remisiewicz, M. Size dimorphism and sex determination in the song Thrush (*Turdus philomelos*) migrating through the southern Baltic Coast. *Ann. Zool. Fenn.* **2020**, *57*, 31–40. [CrossRef]

48. Bond, J. Nidification of the passerine birds of Hispaniola. *Wilson Bull.* **1943**, *55*, 115–125.

49. Townsend, J.M.; Rimmer, C.C.; Latta, S.C.; Mejia, D.; Garrido, E.G.; McFarland, K.P. Nesting ecology and nesting success of resident and endemic tropical birds in the Dominican Republic. *Wilson J. Ornithol.* **2018**, *130*, 849–858. [CrossRef]

50. Allan, R.K.; Wiley, J.W.; Latta, S.C.; Ottenwalder, J.A. *The Birds of Hispaniola, Haiti and the Dominican Republic: An Annotated Checklist*; British Ornithologists' Union: The Natural History Museum: Tring, Herts, UK, 2003.
51. Ndlovu, M. Birdcall lures improve passerine mist-net captures at a sub-tropical african savanna. *PLoS ONE* **2018**, *13*, e0199595.
[CrossRef]

52. CRBPO. Guide de Saisie des Données Issues du Baguage d'Oiseaux v.4; Museum National d'Hiatoire Naturelle: Paris, France, 2018.

53. North American Banding Council. Guide d'Etude des Bagueurs Nord-Américains; North American Banding Council: Point Reyes Station, CA, USA, 2001. Available online: http://www.pwrc.nbs.gov/bbl/resource/nabc.html (accessed on 10 September 2019).

54. Owen, J.C. Collecting, processing, and storing avian blood: A review: Avian blood collection techniques. *J. Field Ornithol.* **2011**, *82*, 339–354. [CrossRef]

55. Bayer, D.M.; Mohan, K.; Jayakumar, K.; Manafi, M.; Pavithra, B.H. Simple cannulation procedure for serial blood sampling through cutaneous ulnar vein in chickens. *J. Appl. Anim. Welf. Sci.* **2012**, *15*, 91–100. [CrossRef]

56. Horváth, M.B.; Martínez-Cruz, B.; Negro, J.J.; Kalmár, L.; Godoy, J.A. An overlooked DNA source for non-invasive genetic analysis in birds. *J. Avian Biol.* **2005**, *36*, 84–88. [CrossRef]

57. Speller, C.F.; Nicholas, G.P.; Yang, D.Y. Feather barbs as a good source of MtDNA for bird species identification in forensic wildlife investigations. *Investig. Genet.* **2011**, *2*, 16. [CrossRef]

58. Cambrone, C. Biology and Population Genetics of the White-Crowned Pigeon *Patagioenas leucocephala*, and the Scaly-Naped Pigeon *P. squamosa*: Implications for Conservation. Ph.D. Thesis, French West Indies University, Guadeloupe, France, 2022; p. 252.

59. Fridolfsson, A.-K.; Ellegren, H. A simple and universal method for molecular sexing of non-ratite birds. *J. Avian Biol.* **1999**, *30*, 116–121. [CrossRef]

60. Dechaume-Moncharmont, F.-X.; Monceau, K.; Cezilly, F. Sexing birds using discriminant function analysis: A critical appraisal. *Auk* **2011**, *128*, 78–86. [CrossRef]

61. Burnham, K.P.; Anderson, D.R.; Huyvaert, K.P. AIC model selection and multimodel inference in behavioral ecology: Some background, observations, and comparisons. *Behav. Ecol. Sociobiol.* **2011**, *65*, 23–35. [CrossRef]

62. R Core Team. *R: A Language and Environment for Statistical Computing*; R Foundation for Statistical Computing: Vienna, Austria, 2022; Available online: https://www.R-project.org/ (accessed on 10 April 2023).

63. Madsen, V. Sex-determination of continental European robins *Erithacus r. rubecula*. *Bird Study* **1997**, *44*, 239–244. [CrossRef]

64. Von Kossel de Andrade Silva, K.; Löbo-Hajdu, G.; Alice, S.; Alves, M. Sex determination in *Turdus amaurochalinus* (passeriformes: Muscicapidae): Morphometrical analysis supported by CHD gene. *Rev. Biol. Trop.* **2011**, *59*, 789–794. [CrossRef]

65. Covino, K.M. Determination of sex using morphometrics in the Northern waterthrush (*Parkesia noveboracensis*) and Swainson's thrush (*Catharus ustulatus*). *Wilson J. Ornithol.* **2015**, *127*, 706–711. [CrossRef]

66. Harvey, M.G.; Bonter, D.N.; Stenzler, L.M.; Lovette, I.J. A comparison of plucked feathers versus blood samples as DNA sources for molecular sexing. *J. Field Ornithol.* **2006**, *77*, 136–140. [CrossRef]

67. Arnoux, E.; Eraud, C.; Navarro, N.; Tougard, C.; Thomas, A.; Cavallo, F.; Vetter, N.; Faivre, B.; Garnier, S. Morphology and genetics reveal an intriguing pattern of differentiation at a very small geographic scale in a bird species, the Forest thrush *Turdus lherminieri*. *Heredity* **2014**, *113*, 514–525. [CrossRef]

68. Wojczulanis-Jakubas, K.; Wietrzykowski, J.; Jakubas, D. Response of Reed warbler and Sedge warbler to acoustic playback in relation to age, sex, and body condition. *J. Ornithol.* **2016**, *157*, 137–143. [CrossRef]

69. Chin, S.; McKinnon, E.A.; Fraser, K.C.; Rotenberg, J.; Stutchbury, B.J.M. No sex bias in Wood thrushes (*Hylocichla mustelina*) captured by using audio playback during the non-breeding season. *Wilson J. Ornithol.* **2014**, *126*, 599–605. [CrossRef]

70. Morrison, C.A.; Robinson, R.A.; Clark, J.A.; Gill, J.A. Causes and consequences of spatial variation in sex ratios in a declining bird species. *J. Anim. Ecol.* **2016**, *85*, 1298–1306. [CrossRef]

71. Uller, T. Sex-specific sibling interactions and offspring fitness in vertebrates: Patterns and implications for maternal sex ratios. *Biol. Rev.* **2006**, *81*, 207–217. [CrossRef] [PubMed]

72. Li, X.-Y.; Kokko, H. Intersexual resource competition and the evolution of sex-biased dispersal. *Front. Ecol. Evol.* **2019**, *7*, 111.
[CrossRef]

73. Cézilly, F.; Préault, M.; Dubois, F.; Faivre, B.; Patris, B. Pair-bonding in birds and the active role of females: A critical review of the empirical evidence. *Behav. Process.* **2000**, *51*, 83–92. [CrossRef]

74. Végvári, Z.; Katona, G.; Vági, B.; Freckleton, R.P.; Gaillard, J.-M.; Székely, T.; Liker, A. Sex-biased breeding dispersal is predicted by social environment in birds. *Ecol. Evol.* **2018**, *8*, 6483–6491. [CrossRef] [PubMed]

75. Aubry, Y.; Desrochers, A.; Seutin, G. Response of Bicknell's thrush (*Catharus bicknelli*) to boreal silviculture and forest stand edges: A radio-tracking study. *Can. J. Zool.* **2011**, *89*, 474–482. [CrossRef]

76. Ricklefs, R.E. Comparative demography of new world populations of thrushes (*Turdus* spp.). *Ecol. Monogr.* **1997**, *67*, 23–43.
[CrossRef]

77. Székely, T.; Liker, A.; Freckleton, R.P.; Fichtel, C.; Kappeler, P.M. Sex-biased survival predicts adult sex ratio variation in wild birds. *Proc. R. Soc. B Biol. Sci.* **2014**, *281*, 20140342. [CrossRef]

78. Robinson, R.A.; Kew, J.J.; Kew, A.J. Survival of suburban Blackbirds *Turdus merula* varies seasonally but not by sex. *J. Avian Biol.* **2010**, *41*, 83–87. [CrossRef]

79. Frey, S.J.K.; Rimmer, C.C.; McFarland, K.P.; Menu, S. Identification and sex determination of Bicknell's thrushes using morphometric data. *J. Field Ornithol.* **2008**, *79*, 408–420. [CrossRef]

80. Dilger, W.C. Hostile behavior and reproductive isolating mechanisms in the avian genera *Catharus* and *Hylocichla*. *Auk* **1956**, *73*, 313–353. [CrossRef]
81. Martin, S.G. The agonistic behavior of Varied Thrushes (*Ixoreus naevius*) in winter assemblages. *Condor* **1970**, *72*, 452–459.
[CrossRef]

82. Loonstra, A.H.J.; Verhoeven, M.A.; Senner, N.R.; Hooijmeijer, J.C.E.W.; Piersma, T.; Kentie, R. Natal habitat and sex-specific survival rates result in a male-biased adult sex ratio. *Behav. Ecol.* **2019**, *30*, 843–851. [CrossRef] [PubMed]

83. Davalos, L.M.; Brooks, T. Parc National La Visite, Haiti: A last refuge for the country's montane birds. *Cotinga* **2001**, *16*, 36–39.

84. Rimmer, C.C.; Goetz, J.E.; Garrido-Gomez, E.; Brocca, J.L.; Bayard, P.; Hilaire, J.V. Avifaunal surveys in La Visite National Park—Last vestiges of montane broadleaf forest in eastern Haiti. *J. Carib. Ornithol.* **2010**, *23*, 31–43.

85. Donald, P.F. Adult sex ratios in wild bird populations. *Ibis* **2007**, *149*, 671–692.

86. Vallès, H.; Labaude, S.; Bezault, E.; Browne, D.; Deacon, A.; Guppy, R.; Pujadas Clavel, A.; Cézilly, F. Low contribution of Caribbean-based researchers to academic publications on biodiversity conservation in the insular Caribbean. *Perspect. Ecol. Conserv.* **2021**, *19*, 443–453. [CrossRef]

87. Exantus, J.-M.; Beaune, D.; Cézilly, F. The relevance of urban agroforestry and urban remnant forest for avian diversity in a densely-populated developing country: The case of Port-au-Prince, Haiti. *Urban For. Urban Green.* **2021**, *63*, 127217. [CrossRef]

88. Saint-Louis, L.J.; Paul, J.-F.; Beaune, D.; Célestin, W.; Cézilly, F. A baseline survey of waterbirds in five major wetlands of Haiti. *Waterbirds* **2021**, *44*, 370–375. [CrossRef]

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