Factors affecting breeding success in the common sandpiper and the
potential impact of disturbance
Abstract
Disturbance by humans and climatic change are thought to be two
important factors contributing to ongoing declines in migratory bird
species, especially during the breeding season when they may impact
productivity. Ground-nesting species with precocial offspring are likely
to be susceptible to both disturbance and extreme weather events, but
more work is needed to understand these processes. Here, we investigate
the factors affecting reproductive success in the common sandpiper
(Actitis hypoleucos), a declining, ground-nesting migratory wader. We
colour-ringed individuals and monitored nests over three years to study
the impact of disturbance, habitat and rainfall on hatching success and
fledging success. First, we investigated whether the distance of nests
from footpaths and rivers, and the amount of vegetation cover, predicted
hatching success. We also recorded the distance at which incubating
adults flushed from the nest in response to an approaching observer.
Second, we investigated whether fledging success was associated with
rainfall in the period following hatching. We found that hatching
success was higher when nests were further away from footpaths, but only
when nests were also far from rivers. Also, individuals on nests that
were far from footpaths left their nests more readily when approached by
observers, particularly when their nests had less vegetation cover.
Further, our data showed that adults sitting tightly on nests, and
having large amounts of vegetation cover around them, had higher
hatching success. Finally, our results showed that fledging success was
correlated with heavy rainfall in the week after hatching. This suggests
that extreme rainfall events are likely to have important consequences
for chick survival. Further work is needed to determine the interacting
effects of human disturbance and predation events on both hatching and
fledging success, particularly in the face of the increasing frequency
of extreme weather events.