Reproductive Ecology and Evolution

For my last birding trip I visited Centennial. I went on Thursday, April 26, 2018 from around 3pm to 5pm. On this day, the high was 58°, the low was 49°F, it was cloudy and started drizzling at the time I left.

Although the weather was not perfect, I heard more songs on this trip than I have on any of the others. I assume this is because more birds are here with mates and territories to protect at this time of the year.

I first saw a pair of Northern Cardinals in a patch of dense shrubs at the forest’s edge. Next I saw a Turkey Vulture soaring above the interior of the forest. I then noticed a pair of Black-capped Chickadees eating on and around a large snag. I also heard many American Robins and Northern Cardinals singing.

Black-capped Chickadees nest in tree cavities 5 to 20 feet off the ground. Their nests typically include moss or other plant matter and a lining of material like animal hair. However, they first have to excavate the tree cavity the female chose in order to make it deeper and wider inside.

Northern Cardinals nest in shrubs or short trees that are usually 3-10 feet off the ground. Their nests are usually made of twigs, weeds, grass, bark strips, and leaves and are lined with fine grass or hair. These materials can be found at forest edges, whereas the Black-capped Chickadees’ nest location and materials are more specific to deciduous and mixed forests.

This correlates to where I saw each pair of species. The Northern Cardinals were in a dense patch of shrubs on the forest’s edge and while the Black-capped Chickadees were about 15 feet up on a snag with many cavities deep in the forest.

Based on where they were when they were singing, I would assume that both are defending prime territory. From the forest’s edge to its interior, the overall health of the forest was good. Although I cannot tell from looking around how abundant these species’ resources are, I had no reason to believe the areas I studied were below average. Hearing a second male Black-capped Chickadee singing not too far from the male I observed also leads me to believe that the area was prime territory. If resource abundance was too low, they would’ve been much more spread out and I would not have been able to hear one and watch another at the same time. Their habitat suggests that both pairs of species I saw were very fit and effectively defending their territory.

Publicado el abril 30, 2018 01:02 MAÑANA por fnovella