CeutaOPEN, individual-based field observations of breeding snowy plovers Charadrius nivosus

Eberhart-Phillips, Luke J.; Cruz‐López, Medardo; Lozano-Angulo, Lydia; Ángel, Salvador Gómez del; Rojas-Abreu, Wendoly; Bucio-Pacheco, Marcos; Küpper, Clemens

doi:10.1038/s41597-020-0490-y

Cited by 8 publications

(4 citation statements)

References 25 publications

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“…The predators of chicks are not well described but likely similar to the egg predator community that includes several mammalian predators such as racoon, opossum, coyote, bob cat, avian predators such as crested caracara Caracara cheriway and reptiles 17 . General field methodology is provided elsewhere 55,56 . In 2017, we took photographs of young (one to 3 days www.nature.com/scientificreports/ old) chicks hiding on the ground, that had already left the nest scrape.…”

Section: Resultsmentioning

confidence: 99%

Neoptile feathers contribute to outline concealment of precocial chicks

Rohr

Volkmer

Metzler

et al. 2021

Sci Rep

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Camouflage is a widespread strategy to increase survival. The cryptic plumage colouration of precocial chicks improves camouflage often through disruptive colouration. Here, we examine whether and how fringed neoptile feathers conceal the outline of chicks. We first conducted a digital experiment to test two potential mechanisms for outline concealment through appendages: (1) reduction of edge intensity and (2) luminance transition. Local Edge Intensity Analysis showed that appendages decreased edge intensity whereas a mean luminance comparison revealed that the appendages created an intermediate transition zone to conceal the object’s outline. For edge intensity, the outline diffusion was strongest for a vision system with low spatial acuity, which is characteristic of many mammalian chick predators. We then analysed photographs of young snowy plover (Charadrius nivosus) chicks to examine whether feathers increase outline concealment in a natural setting. Consistent with better camouflage, the outline of digitally cropped chicks with protruding feathers showed lower edge intensities than the outline of chicks without those feathers. However, the observed mean luminance changes did not indicate better concealment. Taken together, our results suggest that thin skin appendages such as neoptile feathers improve camouflage. As skin appendages are widespread, this mechanism may apply to many organisms.

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Section: Resultsmentioning

confidence: 99%

Neoptile feathers contribute to outline concealment of precocial chicks

Rohr

Volkmer

Metzler

et al. 2021

Sci Rep

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“…We studied the reproductive effort of female snowy plovers at Bahía de Ceuta -an important breeding site located on the coast of Sinaloa, northwest Mexico (23 o 54'N, 106 o 57'W). Details on the study site and population are provided elsewhere (e.g., Cruz-López et al, 2017;Eberhart-Phillips et al, 2020a). In brief, we annually monitored breeding birds from mid-April until early July, and collected mark-recapture data following the methods described in Székely et al, (2008).…”

Section: Data Collectionmentioning

confidence: 99%

Egg size variation in the context of polyandry: a case study using long-term field data from snowy plovers

Eberhart‐Hertel¹,

Rodrigues²,

Krietsch³

et al. 2020

Preprint

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Identifying age-dependent trade-offs between reproductive effort and survival in wild organisms is central for understanding the evolutionary mechanisms of senescence. According to the disposable soma theory, early-life energy investments in reproduction compromise late-life investments in somatic maintenance – leading to senescence. Once thought to only be detectable in captive populations, senescence has recently been documented by several longitudinal studies of wild organisms. However, some reproductive traits that are used to quantify senescence may also be shaped by other age-dependent processes such as mating tactics. For instance, polygamy, which is often positively associated with age, may lead to reduced gamete size due to trade-offs between gamete quantity and quality. Here we investigate how mating behaviour and senescence are associated with reproductive trade-offs of female snowy plovers (Charadrius nivosus). Snowy plovers are long-lived shorebirds (longevity record: 19 years) that produce several nests each year, with females either being polyandrous and sequentially changing partners between breeding attempts or remaining monogamous between attempts. We examined how age, seasonality, and mating tactics affect within-female variation in egg volume using repeated measures collected over a 14-year period. Our results provide clear evidence for senescence in snowy plover females starting at three years of age. Furthermore, females laid smaller eggs in years when they were polyandrous compared to years when they were monogamous, with early- and late-season clutches having the smallest eggs. We suggest that individual female reproductive performance is regulated by flexible mating tactics and age- and season-dependent effects. Our findings highlight the existence of multiple trade-offs for female reproductive investments that likely shape individual variation in lifetime reproductive success. We encourage future research investigating reproductive senescence of wild populations to incorporate age-dependent reproductive investments in light of mating system dynamics.Impact SummaryWhy do organisms senesce at older ages? Life-history theory predicts that early life investments in reproduction compromise future investment opportunities for somatic repair, which leads to senescence. Earlier works assumed that senescence was only observable in captive populations due to the high degree of extrinsic mortality experienced by wild organisms. However, with the expansion of longitudinal studies collecting repeated measures from wild individuals, recent works have identified key insights into the selective processes driving patterns of senescence in nature. Here, we use a 14-year longitudinal mark-recapture dataset of snowy plovers (Charadrius nivosus) breeding in a wild subtropical population in western Mexico to investigate age-dependent trade-offs between female reproductive effort and performance. The snowy plover is a long-lived shorebird characterized by a flexible polyandrous mating system. This rare breeding behaviour represents a unique background for investigating senescence in light of between and within-individual variation in reproductive investment. Our study focused on age-dependent dynamics of egg volume – a convenient measure of a female’s intrinsic reproductive investment, particularly in birds with precocial chicks. We explored age-related correlates of within-female egg volume dynamics while controlling for among-female variation and the confounding effect of trait-dependent (dis)appearance of young (or old) females in the population. Our results show that egg volume expresses an early-life increase followed by a late-life decrease, indicative of reproductive senescence. Furthermore, females tended to lay smaller eggs in years during which they were polyandrous than in years when they were monogamous. Notably, polyandry was not associated with age. As expected, egg volume was highly repeatable within females and clutches. We conclude that age-dependent reproductive effort is an important component driving between- and within-individual variation in reproductive performance of facultatively polygamous species. We encourage future works studying reproductive senescence of wild populations to incorporate age-dependent reproductive investment and mating tactics.

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“…El chorlo nevado prefiere hábitats arenosos que coinciden con el color pálido de su lomo, hábitats costeros de arena seca, y masas de agua interiores, por lo general desprovistos de vegetación (Muir & Colwell 2010, Bird-Life International 2021. La temporada reproductiva va de abril a julio, pero puede iniciar desde marzo y extenderse hasta agosto (Conway et al 2005, Eberhart-Phillips et al 2020. Es un ave que presenta fidelidad al sitio de nacimiento, y a sitios donde ha tenido éxito como reproductor primerizo (Pearson & Colwell 2014).…”

Section: Introductionunclassified

“…Es un ave que presenta fidelidad al sitio de nacimiento, y a sitios donde ha tenido éxito como reproductor primerizo (Pearson & Colwell 2014). Su comportamiento reproductivo está caracterizado por la poliandría con un sesgo hacia mayor abundancia de machos y predominio de cuidados paternales (Eberhart-Phillips et al 2020). Las hembras pueden poner hasta tres nidadas, mientras que es menor en los machos debido a la demanda energética del cuidado de los nidos (Pearson & Colwell 2014).…”

Section: Introductionunclassified

Anidación del chorlo nevado (Charadrius nivosus) en Atotonilco, Jalisco, México

et al. 2022

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El chorlo nevado (Charadrius nivosus) es una de las aves playeras menos abundantes. Es una especie amenazada cuyas poblaciones se encuentran en constante declive. México es importante para las poblaciones de esta especie, pero existe poca información sobre su reproducción y amenazas. Con el objetivo obtener datos sobre su anidación y potenciales amenazas existentes, realizamos un monitoreo de la población del chorlo nevado en la laguna de Atotonilco durante la temporada reproductiva (marzo-julio) del año 2020. Efectuamos conteos de individuos y nidos, tamaño de nidada, fecha aproximada de puesta de los huevos y observaciones sobre las amenazas presentes durante este periodo. Los machos representaron el 85% (n = 140) de la población total y el mes con la mayor cantidad de nidos fue mayo (n = 15). El tamaño promedio de la nidada fue de 2.5 huevos. La superficie de agua fue variable durante los meses de muestreo, pero no se comprobó estadísticamente que a mayor desecación el tamaño de la nidada disminuyera (p = 0.09). Las principales amenazas identificadas fueron los vehículos motorizados y la ganadería. La laguna de Atotonilco es un sitio clave para la reproducción del chorlo nevado y se deben implementar acciones de manejo que permitan ampliar la presencia de agua y regulen las actividades humanas.

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CeutaOPEN, individual-based field observations of breeding snowy plovers Charadrius nivosus

Cited by 8 publications

References 25 publications

Neoptile feathers contribute to outline concealment of precocial chicks

Neoptile feathers contribute to outline concealment of precocial chicks

Egg size variation in the context of polyandry: a case study using long-term field data from snowy plovers

Anidación del chorlo nevado (Charadrius nivosus) en Atotonilco, Jalisco, México

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