Abstract
Artificial incubation is fundamental in ex situ avian conservation interventions for an increasing range of threatened species, but incubation parameters can differ between species. Both egg-turning angle and frequency are critical for successful embryonic development, but measuring these parameters in wild birds has historically been difficult. Using data-loggers inside artificial eggs that accurately record parental egg attendance behaviours, we quantified turning angles and rates throughout the incubation of 6 nesting wild Asian houbaras Chlamydotis macqueenii, a species bred in captivity in response to human over-exploitation. Wild females turned their eggs 0.6 times h-1 with a mean angle of 40.9° turn-1. Mimicking the patterns of wild birds (‘wild’ treatment), we applied a mean angular change of 40-50° turn once h-1 to artificially incubated eggs and compared this to eggs treated with an existing protocol (‘control’) of 120-130° per turn. Mean hatchability for the wild treatment (78.8%, n = 766) was similar to the control (76.6%, n = 1196). The wild treatment (n = 591) produced significantly heavier hatchlings (2.7%) than the control treatment (n = 893). However, chick growth rates (g d-1 and daily % mass change) and survival to Day 10 were not different between groups. The wild treatment demonstrates that turning angles affect embryo development and, perhaps, hatchability. Investigating natural incubation behaviours using egg-loggers and applying these patterns to artificial incubation appears efficacious to achieve optimal incubation protocols and reduce the need for ex situ trial and error refinement in conservation interventions of captive-bred threatened bird species.
Highlights
Ex situ conservation interventions, such as captivebreeding and head-starting, are becoming increasingly important for managing threatened bird species and preventing their extinction (Collar & Butchart 2014)
Artificial incubation practices used in the conservation-breeding of Asian houbaras have been refined by extensive experience over 30 yr, we found that applying the incubation turning parameters measured in wild houbaras to artificial incubators was able to yield similar results to the existing artificial incubation protocols whilst important mass loss management was favourably altered to produce heavier hatchlings
This supports the argument that egg-loggers can provide a short-cut to developing suitable artificial incubation protocols for threatened species in situations where trial and error refinement is not possible
Summary
Ex situ conservation interventions, such as captivebreeding and head-starting, are becoming increasingly important for managing threatened bird species and preventing their extinction (Collar & Butchart 2014). If a species is threatened, a sound understanding of its specific evolutionarily optimised incubation behaviour in the wild can be used to enhance or maximize hatching success (Deeming & Jarrett 2015). Of the 4 incubation parameters, egg turning behaviour has been studied the least in wild birds because of difficulties in observing it accurately. Turning rates, which can be inferred from the repositioning of a bird on eggs, have been shown to vary across bird orders ranging from
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