Sunday, April 20, 2008

Ready, Set, Fledge!

The first successful nest of the season is in the books! I found this Anna's hummingbird nest two weeks ago while Sarah and I were taking Andie for a walk. I noticed an odd bump on a branch, looked closer, and saw two tiny wedge-shaped bills and four beady eyes peeking out over the rim.

The mother selected a small, bare oak tree right next to a sidewalk a few blocks from the apartment.

Though we walk by this tree every day, I totally missed the construction incubation, and early nestling stages. Hummingbird nestlings stay in the nest for about three weeks, so I was able to visit them many times. I usually passed by for a glimpse while walking the dog in the afternoon and night.

Every day the nestlings looked a little different than the day before until they were pretty much indistinguishable from adults.

I have viewed hundreds of nests, many of which have met unfortunate ends, so I consider myself an objective observer unattached from my research subjects. With these little guys, however, I found myself hoping to see them each day and worrying about them at night when temperatures dipped below freezing.

These worries were unnecessary, however, because the nestlings survived cold, snow, hail, and driving rain. They also remained undetected by predators such as scrub jays, house cats, and cooper's hawks that cruise through the neighborhood.

I filled up the entire section of my nest journal devoted to this nest. I plan to use the photos I took to make some watercolors of the nest and nestlings as well.

The nest was only a few meters off the ground, just high enough. My work on hummingbird nests in New Mexico, along with as previous studies, is showing that hummingbird nests built high in trees are more vulnerable to predation than those built in the understory. Our local hummingbird nest appears to be no exception to this trend.

This morning, Andie and I went out for our morning walk and I saw what I thought was a medium size bird near the nest. Instead it was the pair of nestlings perched on a branch inches from their nest. I did not get a picture of the two, but I returned later in the afternoon and tracked down one of the fledglings.

Now that they are safely out of the nest, I will assume that they have a safe post-fledging period since It is unlikely that I would find evidence to the contrary. For most birds, fledgling survival is much understudied in relation to nest survival, due to the difficulty of tracking down fledglings. Technology is helping to fill this gap in our knowledge, but in this case, I am happy to conclude that all is well for this tiny family.

1 comment:

NW Nature Nut said...

I have never been fortunate enough to find a hummer nest, although I believe I might have a couple of juviniles hanging around right now. I posted some photos of one bathing yesterday. Thanks for sharing the photos. I'd love to see you post some watercolors when you complete them.