How do ground-nesting waders protect their eggs?
Wader expert Graham Appleton answers your wild question.
Waders have various strategies to safeguard their eggs.
Ringed plovers, for instance, hide them among the shingle at the top of beaches; redshanks conceal theirs in clumps of grass.
However, the birds employ an extra trick to outwit ground predators such as Arctic foxes, which seek out food using their noses: they become less smelly in the breeding season.
Research by Jeroen Renerkeens and colleagues in the Netherlands has shown that the composition of the oil that is secreted from waders’ preen glands changes in the spring, with monoester waxes replaced by diesters, which have a weaker scent.
This was first discovered in the red knot and then another 18 species, breeding in both High Arctic and temperate conditions.
Waders secrete diesters for the whole brooding period, minimising the scent that transfers to the eggs.
Interestingly, the researchers found that the amount of diester production is lowest in male ruffs and curlew sandpipers – two species in which the females undertake all of the incubation duties.