Do you know what bird parasitism is?

Birdwatching Panama

Bird parasitism is when one bird lays her eggs in the nest of a different bird species, with the intent that this other bird, the host, will take care of the laying bird’s offspring.  This is  definitely a very smart strategy for the parasite birds, because thanks to this behavior, the parasite birds, do not have to spend all the time and energy raising their chicks.  This allows parasitic layers them to produce more eggs per year.

Around Tranquilo Bay, is one specie of bird that is a parasitic layer of eggs in the nests of other birds.  I´m talking about the Giant Cowbird (Molothrus oryzivorus) who lays her eggs in the Montezuma Oropendola’s (Psacolius montezuma) nest.  In other areas, cowbirds parasite lay in the nests of several other species of oropendolas and caciques.  All those species nest colonially (several nest in one single tree) and build long hanging nests.

Birding Panama

Cowbirds are calm and quiet birds that like to spend time on grassland, looking for insects which is their main diet. The distribution range of the species goes from southern Mexico to northern Argentina.

Another example of parasitic nesting birds is the Common Cuckoo (Cuculus canorus), that lay its eggs in other species nest, and when the chicks hatch they pull out of the nest the eggs and/or chicks of the host.  In the case of the Giant Cowbird, the offspring do not destroy the eggs or chicks of the host specie (the photo at the top shows a Wren (left) feeding a chick of Common Cuckoo), source:
http://www.pbs.org/wgbh/nova/sciencenow/0407/03-moth-06.html )

The tower is perfect place to see the oropendolas flying by, and sometimes is possible to see a few cowbirds flying with them. I took this picture of a Giant Cowbird a while back, when a group of Montezuma Oropendolas stop on the balsa tree near the observation tower, and this cowbird was with them.

Parasitic bird nesting in Bocas del Toro

Save

Leave a Reply