Resumen de Vigilance behaviour of preening black-tailed godwit Limosa limosa in roosting flocks
Jesús Domínguez Conde, María Vidal
Aims: The vigilance behaviour of preening black-tailed godwits Limosa limosa was studied during postbreeding migration.
Location: Salt pans situated in the Parque Natural de las Marismas del Odiel (ría de Huelva, Spain).
Methods: Actively preening birds were arbitrarily selected. Each bird was observed for 2 minutes using a 20-60 x 60 telescope. For each focal bird air temperature, windspeed (using an anemometer), distance to the nearest conspecific at the start of monitoring, number of individual godwits and other waders and gulls in a radius of 10 m of the sampled bird and godwit position (central or peripheral) were recorded. Dependent variables recorded were vigilance time, scanning rate and scan duration.
Results and Conclusions: Vigilance time and scanning rate were higher in peripheral godwits than in central godwits, while mean scan duration did not differ significantly between both groups. Using as predictors godwit position (central vs peripheral), presence or absence of black-headed gull and air temperature the best model to explain vigilance time (Akaike weight, wi = 0.248) and scanning rate (wi = 0.427) included in both cases the godwit position, presence of black-headed gulls and air temperature. Godwit position was a consequential predictor with a negative effect of the central sites in the vigilance time and scanning rate. Black-headed gull presence and air temperature were two consequential predictors that influenced the increase of the vigilance time and scanning rate in roosting godwits. Birds may make postural changes to alter heat loss and we suggest that to increase heat loss the head may be more frequently raised after preening bout. In accordance with this hypothesis, in high temperatures the head rising in preening godwits could have antipredatory and thermoregulatory functions.
