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Army ant invasion of leatherback nests in Gabon

Egg mortality is one of the main factors affecting life history and conservation of oviparous species. A massive and cryptic colonisation of many leatherback turtle (Dermochelys coriacea) eggs is presented in the most important rookery for the species in Gabon. A total of 163 nests were exhumed at Kingere beach, revealing that only 16.7% of eggs produced hatchlings. In the 59% of the nests, more than half of the eggs were dead and attacked by invertebrates and 94% had at least one egg affected by invertebrates. The rate of eggs and SAGs (yolkless eggs) affected by invertebrates within a clutch ranged from 0% to 100%, with an average proportion of 39% and 52%, respectively. The most common invertebrates interacting with the eggs were ghost crabs and insects that affected 51% and 82% of the nests, respectively. Crab and insect co-occurred in 33% of the affected nests. Ants, identified as Dorylus spininodis (Emery 1901) were found in 56% of the excavated nests. However, it was not possible to determine if the ants predated alive eggs or scavenged dead eggs. Very often, hundreds of ants were found drowned within dead eggs. Termites and other invertebrates were associated with the clutch environment and identified as opportunistic feeders, being this is the first record of interaction between termites and sea turtle eggs. An unusual ecological interaction within the leatherback clutches between termites and ants was found in 11% of the nests. The abrupt transition between the soil forest and the beach might be favouring a thriving microbial and invertebrate activity in the sand profile that colonises the nests. informacion[at] Ikaran et al (2020) Cryptic massive nest colonisation by ants and termites in the world's largest leatherback turtle rookery Ethol Ecol Evol 2020. Doi 10.1080/03949370.2020.1715487
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Dark pigmentation limits thermal niche position in birds

Dark pigmentation limits thermal niche position in birds

Animal pigmentation has evolved because of several adaptive functions. In the case of pigmentation produced by melanins, the most common pigments in animals, the main function is protection against UV radiation. However, pigmentation also affects animal surface's ability to absorb solar radiation and gain heat, which may represent a thermal constraint for endotherms due to their relatively high and constant body temperatures. As darker colours absorb more radiation than lighter colours, dark-pigmented endotherm animals may exhibit limited performance under high ambient temperatures and thus be constrained at occupying hot environments. While the influence of pigmentation on the determination of the thermal niches of ectotherms, particularly reptiles, has been the focus of several studies, this remains an unexplored issue for endotherm animals. Here a detailed quantification of the expression of pigmentation phenotypes produced by melanins in 96 species of birds inhabiting the Spanish sector of the Iberian Peninsula was made, and their climate niche position was estimated by calculating the effects of ambient temperature, insolation and precipitation on bird occurrence at a fine 10 x 10 km spatial scale. After controlling for the body size and the nocturnal condition of species, and for phylogenetic and spatial effects, a positive association was found between plumage reflectance and the functional response of bird distribution to spring-summer ambient temperature and insolation but not to precipitation. Thus, bird species preferentially occupying the hotter and sunnier areas of Spain exhibit lighter plumage pigmentation. A similar association between pigmentation and preferences regarding precipitation in geographical distribution was not found. These findings suggest that darker birds are limited from occupying environments with high temperatures, unveiling a constraint in endotherms imposed by their pigmentation phenotype. informacion[at] Galván et al (2018) Dark pigmentation limits thermal niche position in birds. Funct Ecol doi:10.1111/1365-2435.13094