Abstract
Habitat selection determines an animal’s spatial distribution at various
scales. In ground breeding birds, selecting the right nesting location
can be decisive for the survival of parents and offspring. Ruffs
(Calidris pugnax) are waders with highly divergent sex roles that
frequently breed in coastal wetlands of higher latitudes where they
often face the threat of flooding and predation. Males aggregate for
competitive display to attract females (reeves), who then care for the
nest and offspring alone. We investigated which environmental and social
cues relate to nest distributions in this threatened wader species.
Using nest and lek locations from five breeding seasons we tested
whether Ruff nests are randomly distributed across suitable breeding
habitat or show some level of aggregation. We then assessed whether leks
and nests are spatially associated, i.e., nests are closer located to
leks than expected by chance. Finally, we examined whether reeves
consider distance to shoreline and meadow edges, two habitat features
that are linked to threats such as flooding and predation, for the
choice of their nest location. Our results show that nest distribution
is non-random, and nests are found closer to leks and other nests than
expected by chance. We found nests further away from the meadow edges
and shores than expected by chance suggesting that nesting females try
to minimize the risk of predation and flooding. We suggest that
understanding the social and environmental factors affecting female nest
choice can help to improve the management and conservation routines at
the breeding sites of these threatened waders. Our results indicate that
lekking sites can be used to recognise areas of conservation and
management value.