Nalle Bunny Run 2017-07-22

Three people joined me this morning for the monthly group walk on Hill Country Conservancy's Nalle Bunny Run Wildlife Preserve. When I arrived at the preserve at about 7:30 AM as soon as I got out of my car I saw and heard a large group of mostly Blue-gray Gnatcatchers making alarm calls in a small area in a cedar elm tree. I estimated there were ten gnatcatchers, more than I've ever seen together before. Other species of birds including Northern Cardinals, Carolina Chickadees, and even a hummingbird were all in the same small area watching very intently.

This is a defensive behavior small songbirds have when they find some kind of predator. The mobbing and scolding behavior is mostly to warn other birds and animals of the predator's presence, and also to try and drive the predator away. I carefully searched the area up in the tree where the birds were most concentrated. Often the gnatcatchers would hover in the air as well as perch on nearby twigs and branches. After several minutes of searching, and starting to wonder if there really was anything there for the birds to be worried about, I finally spotted this snake laying across the branches with its head hanging low:

The snake was a Western Rat Snake, a nonvenomous common and beneficial animal in the Austin area. This one was about two feet long. As I watched it, the original group of birds left, but periodically new birds would arrive and start the scolding and mobbing again. I was happy that the snake stayed there long enough for all the hikers to arrive. Everyone got the see the snake and the birds' alarm behavior around it. One of the birds that showed up was this almost completely bald Northern Cardinal:

This time of year lots of songbirds are finished raising their broods and can now spend energy replacing their feathers (molting). It's common to see Northern Cardinals like this that lose all of their head feathers at once. They're appearance is quite alarming before their new feathers grow in. But most birds just look messy or disheveled while they're molting, as they lose and replace feathers at different times. This Carolina Wren that was also keeping an eye on the snake had this more common molting appearance:

Other highlights of the morning included this juvenile Red-tailed Hawk which we hard calling from near the spring long before we finally got this clear look at it from the northeast corner of the preserve:

The hawk flew off shortly after I took this photo, but later on after we'd left this area it returned to this tree with a dramatic partial diving arial maneuver with half-folded up wings, right over our heads!

We briefly watched this large wasp digging in the sand. I thought it might be an Eastern Cicada Killer but I look forward to getting some help from the iNaturalist community to know for sure:

Sometimes the air was full of dragonflies, mostly kinds that hunt on the wing like Wandering Gliders, Spot-winged Gliders, and Red Saddlebags. But we also found a Roseate Skimmer, a Neon Skimmer, and two Halloween Pennants (one male and one female). Here's the male:

We found 28 species of birds, and here's our complete list on eBird.

Here are a few more photos on Flickr.

And attached below are the photos as iNaturalist observations.

Posted on 22 July, 2017 21:51 by mikaelb