Our last post shared some pretty intense videos of predation events at nests. In both videos all of the chicks got eaten, and the parents either fled or did not approach the nest while the predator was there. The badger and the 13 lined ground squirrel weren’t challenged as they made off with nestlings. It’s not always like this, though. It turns out that bird parents respond differently depending on who is trying to eat their chicks.
While adult birds and eggs are vulnerable during incubation, they are at even greater risk after chicks hatch. Most of our grassland birds are altricial as chicks, and need to stay in the nest long enough to be reasonably mobile when they fledge. However, chicks are also very vulnerable in the nest: they stay in one place, and the noise and activity surrounding the nest can attract predators. These birds need to balance the benefits of staying in the nest until they are able to fly to forage and escape predators with the potential risks of being found by predators while still in the nest.
A lot of people really dislike - even hate - cowbirds. I get it. It can be hard to watch a small warbler trying to keep a huge cowbird chick fed, and it’s sad when host species eggs get destroyed. But objectively and unemotionally, cowbirds are amazing, smart, resilient, and cool. Their reproductive strategy allows them to produce many more offspring than the average bird. Hopefully by the end of this post, you’ll be thinking about cowbird behavior in a new light too.
Keeping the nest clean is a pretty big deal. Some large raptors are able to defend their nest from nearly anything, so it doesn’t matter how messy they are. Not so for our grassland birds. They are ill-equipped to fight back against most predators, and fare much better when they’re able to go unnoticed. Dirty nests could smell strongly, and attract curious - and hungry! - mammalian predators.
It's been a little bit since we've peeked Into the Nest of grassland birds. But not because of a lack of interesting stuff to talk about! We are working on a run down of everyone's favorite topic: poop; you won't want to miss the upcoming post on fecal sacs.
In the meantime, feast your eyes on these awesome eggs. The size, shape, color pattern are all unique to the species they come from. Learn more about how grassland birds lay their clutch of beautiful eggs in our Into the Nest post from May 31: There is nothing so beautiful as a bird's egg.