LACK OF HATCH DATE ADJUSTMENT IN RESPONSE TO WEATHER IN FOUR ARCTIC-BREEDING SHOREBIRDS

Abstract

Many species of shorebirds breed in the Arctic. Even in summer, severe weather events can result in decreased growth rates and mortality for chicks, both through exposure and decreased prey abundance, affecting chicks’ fitness. An earlier study suggested that shorebirds could delay hatch dates in the case of inclement weather to minimize chicks’ exposure; this could explain observed variation in incubation length. In this paper I look for statistical evidence that hatch dates can be brought forward or delayed in response to weather. I looked at data collected in Barrow, AK, during the summers 2003 to 2014 on 12 meteorological variables and four shorebird species: pectoral sandpiper (Calidris melatonos, n=388), dunlin (Calidris alpina, n=226), semipalmated sandpiper (Calidris pusilla, n=203), and red phalarope (Phalaropus fulicarius, n=503). I compared the average weather on nest hatch dates to the previous and subsequent days for each variable and species. Though there was substantial variation in incubation length, no meteorological variable differed significantly between the hatch dates and the surrounding days for any species; this implies that shorebirds do not adjust hatch dates in response to weather. Even if shorebirds do possess this ability, delaying hatch dates could have detrimental effects, including leaving less time for development and causing parents to incubate for longer. This suggests that shorebirds may be less adaptable to the more frequent extreme weather expected as a result of climate change.