Babs' Birding Experiences : Boyce Thompson Arboretum SP, Superior, Pinal County, AZ

Monday, September 14, 2015

Why did I visit Boyce Thompson Arboretum (BTA) again so soon?

After having a rare visit by a Kentucky Warbler (KEWA) confirmed at BTA yesterday, I was not going to lay in bed and say, “It’s a needle in a haystack.” It would be a Life Bird for me should I happen to lay eyes on it, so off I went, making my plan as I drove east after a rainy night.

In my “sit-on” bucket (has a lid for sitting comfort), I stuffed a raincoat, camera and, more optimistically, clip-on sunglasses. The gate opened slightly before 6 a.m. which enabled me to reach my destination in the Demonstration Garden shortly after 6:00. Since the Kentucky Warbler is a “skulker”, I chose a spot that appeared to have the same ground cover as in the AZFO photograph posted yesterday and lots of adjacent ground-hugging plants for a bird to hide. (Arizona Field Ornithologists [AZFO] maintain a site to catalogue photos, recordings, etc. of unusual sightings.) For 45 minutes I listened and watched patiently at that spot for my “target” bird. Quite dark in this early hour, several birds came into the trees nearby where I discerned ID by shape, size and behavior. Being able to swivel around 360° on the comfortable seat, I kept my eye on adjacent plant areas, too.

There is a lot of good habitat in the Demo Garden for skulkers, so I moved my bucket to a more secluded spot. After about 10 minutes, I noticed another birder; he had seen me, too. When I was ready to move from that spot, I sought out Darrel Wilder, the birder who had observed me. We continued in our own ways to seek out the same bird. It was nice to know more of the Demo Garden would get covered, so I found another sitting spot where I stayed for about 15 minutes. Wandering through the west end of the garden, then, I walked up to the water feature in the northeast corner to check out that spot. Darrel was already there! He had not see the KEWA either, but had come upon an early Lincoln’s Sparrow. He left the area so I sat there for another 15-20 minutes but saw very little and his LISP was a no-show for me. However, another birder walked past on the entrance trail on the other side of some trees and shrubs. Janine may have seen me, or not. We never did cross paths but continued birding the Demo garden quietly and individually.

Many resident birds were vocal: Curve-billed Thrasher, Cactus Wren, and Verdin. Verdin, the tiny acrobatic gray bird with a yellow head, are one of our smallest song birds. Their security-nests intrigue me. They build nests for both breeding and sleeping with the roosting nest being the smaller of the two. The male constructs the stick shell while the female does the interior lining. The nest is not the typical bowl shape of some birds, but is closed at the top and accessed from the bottom or low side. This technique provides security from larger birds that might want to fly in and steal eggs in nesting season. In summer, the hole on the side of the nest appears to catch the wind for some air conditioning.

The rectangle of sticks is the opening to this Verdin nest

I moved to several other likely spots for the Kentucky Warbler within the Demo Garden before leaving. My heart beat extra fast when my eyes landed on a warbler in a tree that came close to the description of the “target” but it was one I was too familiar with to call it anything but Townsend’s Warbler. It was gone before I could get a photo but, unfortunately, I didn’t doubt my call.

Before leaving BTA, I walked to the south end of the picnic area where Turkey Vultures (TVs) appeared to be flying in circles that would eventually become “kettles” or columns stretching up toward the clouds. Although my photo doesn’t reveal the red head of the vultures, it does show clearly the two-toned underwing — dark on the front edge; light on the rear edge.

Turkey Vultures gathering to form a kettle

Because there is a hawk that looks similar to the TVs, I always scan these gathering groups in search of it. Using the camouflage of the TVs (who are scavengers and no threat to small birds that see them), the Zone-tailed Hawk can fly with them until it sees prey. Suddenly, it leaves the “kettle” surprising some unsuspecting smaller bird or animal.

There were no Zone-tailed Hawks within the gathering vultures, but I spotted one circling from the south toward them. As it got closer, I managed identification photos.