Killdeer nesting behavior in hot climates

[Alan Melle]

This Killdeer is shielding the nest and eggs from the sun in a hot climate. The ambient temperature was 98° F and the ground temperature exceeded 125° F. Both adults incubate the eggs and periodically the sitter would leave the nest and fly off to a nearby pond for a good soaking and then return to the nest. This one has just returned and you can see the wet feathers on the bird’s breast. The wet feathers help the bird stay cool and keep the eggs from getting too hot. The birds stand over the eggs during the day and only actually sit on them after the sun goes down. At least this gave me a chance for an image of the Killdeer with the eggs.

As for proper sun angle…. this is the best it gets! The birds keep their back to the sun to provide the maximum amount of shade to the eggs. They repositioned themselves frequently so that the sun was behind them all day. It worked, all three eggs hatched Sunday!

D300, 600mm & 1.4xTC, SB-800 FP flash on manual at full power

[William Malacarne]

Also important is that it adds humidity to the eggs. When we incubate parrot egg we keep the humidity at 50% until just before they are due to hatch then it is raised to around 80%. It is pretty low humidity, typically less than 30%, where we live and our parent birds that are incubating will also bath regularly to do this same thing.

Bill

[Axel Hildebrandt]

Very interesting behavior captured. This kind of shielding looks really exhausting. Thanks also for explaining the humidity issue, William.

[Anita Rakestraw]

Odd that these birds nest right out in the open among rocks, instead of finding a sheltered area where the eggs would not get so hot! Then they have to go to all this extra work to keep the eggs from overheating!