Population monitoring and modelling of yellow‐shouldered parrot on Bonaire, Caribbean Netherlands

Rivera-Milán, Frank F.; Simal, Fernando; Bertuol, Paulo; Boomer, G. Scott

doi:10.2981/wlb.00384

Cited by 5 publications

(8 citation statements)

References 54 publications

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“…Contrarily, we recommend DS modeling when researchers focus on one or a few common species, as they can then obtain more precise estimates of abundance by increasing the number of encounters (not paying attention to the rest of the species) and the best-fitting detection functions, as is done with point counts and line transects [13]. Even more importantly, DS modeling allows the calculation of densities that can be carefully extrapolated to the extent of suitable habitat and thus estimate the size of parrot populations, as has been done using point counts on islands [24,58]. A stratified design of large-scale roadside surveys could allow the estimation of population sizes for common parrot species with country-and even continental-level distributions, something that could be logistically unaffordable through point counts and walked line transects.…”

Section: Pros and Cons Of Distance Samplingmentioning

confidence: 99%

“…However, incorporating these estimates of an unseen number of individuals into DS modeling is challenging given the difficulties of estimating their distances of detection. Some solutions have been proposed when conducting parrot walked line transects and point counts, such as measuring distances to other objects at a similar distance if the heard parrot/flock was not visible [13,24] or categorizing these estimated distances to unseen parrots into intervals [58]. These estimations require expert observer skills and thus, researchers must be careful to do not introduce distance biases that would affect DS density estimates [38].…”

Section: Pros and Cons Of Distance Samplingmentioning

confidence: 99%

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Roadside Car Surveys: Methodological Constraints and Solutions for Estimating Parrot Abundances across the World

et al. 2021

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Parrots stand out among birds because of their poor conservation status and the lack of available information on their population sizes and trends. Estimating parrot abundance is complicated by the high mobility, gregariousness, patchy distributions, and rarity of many species. Roadside car surveys can be useful to cover large areas and increase the probability of detecting spatially aggregated species or those occurring at very low densities. However, such surveys may be biased due to their inability to handle differences in detectability among species and habitats. We conducted 98 roadside surveys, covering > 57,000 km across 20 countries and the main world biomes, recording ca. 120,000 parrots from 137 species. We found that larger and more gregarious species are more easily visually detected and at greater distances, with variations among biomes. However, raw estimates of relative parrot abundances (individuals/km) were strongly correlated (r = 0.86–0.93) with parrot densities (individuals/km2) estimated through distance sampling (DS) models, showing that variability in abundances among species (>40 orders of magnitude) overcomes any potential detectability bias. While both methods provide similar results, DS cannot be used to study parrot communities or monitor the population trends of all parrot species as it requires a minimum of encounters that are not reached for most species (64% in our case), mainly the rarest and more threatened. However, DS may be the most suitable choice for some species-specific studies of common species. We summarize the strengths and weaknesses of both methods to guide researchers in choosing the best–fitting option for their particular research hypotheses, characteristics of the species studied, and logistical constraints.

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Section: Pros and Cons Of Distance Samplingmentioning

confidence: 99%

Section: Pros and Cons Of Distance Samplingmentioning

confidence: 99%

Roadside Car Surveys: Methodological Constraints and Solutions for Estimating Parrot Abundances across the World

et al. 2021

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“…1A). Details of conventional distance sampling and the abundance estimator used are provided in Buckland et al (2001Buckland et al ( , 2015, Burton & Rivera-Milán (2014), Thomas et al (2010) Marques (2012), andRivera-Milán et al (2018). For the analysis, we used DISTANCE 7.1 ver.…”

Section: Conventional Distance Samplingmentioning

confidence: 99%

“…Temporal changes in abundance were modelled with a discrete form of the standard logistic equation in the presence of human-induced mortality (Rivera-Milán et al 2018):…”

Section: Bayesian State-space Logistic Modelmentioning

confidence: 99%

“…Lastly, we used survey-based abundance estimates to develop a Bayesian statespace logistic model, generate the posterior distributions of maximum pop u lation growth rate, population carrying capacity, equilibrium popula-tion abundance, maximum sustainable humaninduced mortality rate and maximum sustainable total number of deaths from human-induced mortality. We make model-based abundance predictions for 2019−2030, accounting for observation and process variance and uncertainty from human-induced mortality (Rivera-Milán et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Green and hawksbill turtle abundance and population dynamics at foraging grounds in Bonaire, Caribbean Netherlands

Rivera-Milán¹,

Nava²,

Schut³

et al. 2019

Endang. Species. Res.

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Green turtles Chelonia mydas and hawksbill turtles Eretmochelys imbricata are negatively impacted by natural and anthropogenic disturbances. Unknown numbers of turtles are killed annually in the coastal waters of Bonaire and Klein Bonaire, Caribbean Netherlands. We used N-mixture models, conventional distance sampling and the multiple Lincoln-Petersen method to estimate abundance from transect-count and net-capture surveys. Maximum likelihood and Bayesian generalised linear models were used to assess trends in annual abundance in 2003−2018, and a Bayesian state-space logistic model was developed to generate the posterior distributions of population parameters and make abundance predictions for 2019−2030. Mean ± SE annual abundance was 555 ± 149 green turtles (2.5 th and 97.5 th percentiles = 337, 943) and 70 ± 13 hawksbill turtles (49, 101), and there were no trends in western Bonaire and Klein Bonaire in 2003−2018. Mean annual abundance was 348 ± 135 green turtles (171, 731) and there was a positive trend inside Lac Bay, southeast Bonaire, 2003−2018. Green turtles have higher population growth rate and carrying capacity, and therefore can sustain higher human-induced mortality than hawksbill turtles. However, under low mortality rates (< 0.100), both species can fluctuate stably between the lower and upper limits of the carrying capacity. The methodology implemented can be adapted to estimate sea turtle abundance, monitor and model their population dynamics, and assess the negative impact of human-induced mortality in other Caribbean islands.

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Bridled Quail-doveGeotrygon mystaceapopulation assessment after hurricanes Irma and Maria, St. Eustatius, Caribbean Netherlands

Rivera-Milán

Madden

Verdel

2021

Bird Conservation International

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Summary Structural vegetation damage and food limitation are important effects of major hurricanes, particularly for fruit/seed-eating, forest-dependent Caribbean birds with restricted distributions and small populations, such as the Bridled Quail-dove Geotrygon mystacea. Motivated by the lack of abundance estimates, corrected for detection probability, we conducted distance-sampling surveys inside and outside the Quill National Park each May in 2016-2019. Detection mode was the most important covariate, with others receiving no support from the data. Detectability of available single individuals and clusters of individuals within 60 m of transect centrelines averaged 0.957 ± 0.114 standard error for audio detections, 0.434 ± 0.052 for visual detections, and 0.693 ± 0.064 for detection modes combined. Availability averaged 0.475 ± 0.138 and the product of detectability and availability averaged 0.329 ± 0.098. Density averaged 1.459 ± 0.277 individuals ha-1 and population size averaged 642 ± 122 individuals in 440 ha. Density did not differ along and away from forest trails, but was higher inside than outside the park and at elevations within 201-400 m than 100-200 m and 401-600 m. Density declined by 76% after hurricanes Irma and Maria in 2017. We suggest that major hurricanes together with free-ranging livestock overgrazing degraded foraging habitats, limited food supply, and caused a population bottleneck. Our methodology can be implemented across the distribution range to assess population status and trends and evaluate the result of management actions at key conservation sites. Bridled Quail-dove populations probably were declining on most islands before the 2017 hurricanes and population status warrants revision.

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Population monitoring and modelling of yellow‐shouldered parrot on Bonaire, Caribbean Netherlands

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 5 publications

References 54 publications

Roadside Car Surveys: Methodological Constraints and Solutions for Estimating Parrot Abundances across the World

Roadside Car Surveys: Methodological Constraints and Solutions for Estimating Parrot Abundances across the World

Green and hawksbill turtle abundance and population dynamics at foraging grounds in Bonaire, Caribbean Netherlands

Bridled Quail-doveGeotrygon mystaceapopulation assessment after hurricanes Irma and Maria, St. Eustatius, Caribbean Netherlands

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