Abstract
BackgroundParental care often increases offspring survival, but is costly to the parents. A trade-off between the cost and benefit of care is expected, so that when care provisioning by both parents is essential for the success of young, for instance in extremely cold or hot environments, the parents should rear their young together. We investigated the latter hypothesis in a ground nesting shorebird, the Kentish plover Charadrius alexandrinus in an extremely hot environment, the Arabian Desert. Midday ground temperature was often above 50°C in our study site in Abu Dhabi (United Arab Emirates), thus leaving the eggs unattended even for a few minute risks overheating and death of embryos.ResultsThrough the use of video surveillance systems we recorded incubation routines of male and female Kentish plovers at 28 nests over a full day (24 h). We show that ambient temperature had a significant influence on incubation behaviour of both sexes, and the relationships are often non-linear. Coordinated incubation between parents was particularly strong in midday with incubation shared approximately equally between the male and the female. The enhanced biparental incubation was due to males increasing their nest attendance with ambient temperature.ConclusionsOur results suggest biparental care is essential during incubation in the Kentish plover in extremely hot environments. Shared incubation may also help the parents to cope with heat stress themselves: they can relieve each other frequently from incubation duties. We suggest that once the eggs have hatched the risks associated with hot temperature are reduced: the chicks become mobile, and they gradually develop thermoregulation. When biparental care of young is no longer essential one parent may desert the family. The relaxed demand of the offspring may contribute to the diverse breeding systems exhibited by many shorebirds.
Highlights
Parental care often increases offspring survival, but is costly to the parents
We investigated parental cooperation - defined here as mutually beneficial interactions between the parents to maximise their reproductive success [31] - in a small cosmopolitan ground-nesting shorebird, the Kentish plover, Charadrius alexandrinus, which breeds in temperate and subtropical environments [32,33,34]
The objectives of our study were to answer two questions: i) Is the behaviour of the male or the female influenced by ambient temperature? ii) Does ambient temperature influence parental cooperation during incubation? We predicted that (i) male contribution to incubation should increase with ambient temperature to assist female incubation, and (ii) total incubation will increase with ambient temperature, so that parental coordination will be tight during the hottest part of the day
Summary
A trade-off between the cost and benefit of care is expected, so that when care provisioning by both parents is essential for the success of young, for instance in extremely cold or hot environments, the parents should rear their young together We investigated the latter hypothesis in a ground nesting shorebird, the Kentish plover Charadrius alexandrinus in an extremely hot environment, the Arabian Desert. Biparental care, is a common behaviour in certain groups of animals: for instance 40% of cichlid fish genera and 32% of primate species are biparental [5] These species provide excellent opportunities to investigate how and why biparental care evolves, and to tease apart the roles of parental investment, sexual selection and conflicts in breeding system evolution [sensu-[6,7,8,9]]. Staying with the mate and helping him/her might be beneficial if there are few opportunities for finding a new mate [4]
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