The influence of a hot environment on parental cooperation of a ground-nesting shorebird, the Kentish plover Charadrius alexandrinus

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.

The Challenge of Coping in an Extremely Hot Environment: A Case Study of the Incubation of Lesser Crested Terns (Thalasseus bengalensis)

“…The influence of ground temperature on the incubation behavior was investigated using linear mixedeffect models (Pinheiro and Bates 2000;AlRashidi et al 2010), with nest identity as the grouping structure. The model included a random intercept term for each nest.…”

“…The ground temperature was included in the model as a second degree orthogonal polynomial covariate. The correlation between the time period and the temperature was also included in the model because the effect of temperature on incubation may vary throughout day (AlRashidi et al 2010). Additionally, the influence of the position of the sun on the incubation behavior was investigated using linear mixed-effect models.…”

Incubation Routine of Saunders's Tern Sternula Saundersi in a Harsh Environment

“…Ground temperature was included in the model as second degree orthogonal polynomial covariate because Conway and Martin (2000) found that avian incubation behaviour and ambient temperature were not linearly associated. The interaction between time period and temperature was also included in the model, as the effect of temperature on incubation may vary over the day (AlRashidi et al, 2010). Total incubation percentages were arcsine squareroot transformed to achieve normality.…”

“…Each day was divided into 12 2-hour time periods. Total incubation as the percentage of time when the eggs were incubated by either parent was calculated for each period following AlRashidi et al (2010). The average temperature outside the nests was taken as the ground temperature for each period.…”

Triploid plover female provides support for a role of the W chromosome in avian sex determination

“…Twentyfive microlitres of blood were taken from either the brachial vein (adults) or metatarsal vein (chicks) and stored in Queen's lysis buffer [9]. The female and her mate were sexed in the field based on plumage characteristics and sex-specific pattern of incubation in this species [10][11][12]. Molecular sexing using P2/P8 primers to amplify W-and Z-specific chromohelicase DNA binding protein fragments [13] confirmed the phenotypic sexing results of adults and showed that all three chicks were male.…”