The effects of heat stress, predation risk and parental investment on Malaysian plover nest return times following a human disturbance

Mai Yasue┬┤*, Philip Dearden

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A B S T R A C T
Waders leave nests and conduct distractive displays when approached by people. The time
taken for waders to return to nests depends on numerous factors that affect the costs and
benefits of incubation and anti-predator behavior. Understanding this trade-off may help
assess the reproductive consequences of different nest return times and identify variables
to consider in breeding disturbance studies. We subjected 73 Malaysian plover (Charadrius
peronii) nests to standardized human disturbances and an analysis of covariance was used
to determine how weather, time of day, embryonic age, weeks into breeding season and
nest attendance (proportion of time adults incubated nests) influence nest return times.
Egg temperatures were estimated using a regression model that predicted the temperature
inside unshaded eggs from air temperature, cloud cover and time of day (r2 = 0.88). We
assessed the relationship between nest return times and hatch success. Plovers returned
to nests faster at higher modeled egg temperature (P = 0.010), in the morning (P = 0.003),
if they had younger clutches (P = 0.038), and if they had high nest attendance prior to the
disturbance (P = 0.015). Pairs that returned to nests faster had lower hatch success
(P = 0.021). This may be because pairs that spend more time distracting humans may also
do so for predators. These results suggest that short nest return times may not indicate low
fitness costs of disturbance. The thermal and predation environment in addition to nest
return times should be taken into account when assessing the deleterious effects of human
disturbance.

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The effects of heat stress, predation risk and parental investment on Malaysian plover nest return times following a human disturbance by Te Arai Kete is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 New Zealand License