Summer Bird Songs Waning

My experience with Breeding Bird Censuses are most birds are identified by song. However, as the breeding season progresses I am detecting more birds by visual ID. Today that threshold has been reached. There really were not a lot of birds singing, a product of fledged young and moving family units. White-eyed Vireos continue to be vocal along with a few Painted & Indigo Buntings. Golden-cheeked Warblers have been quiet for two weeks now, yet I still see individuals at Twin Falls.

I did hear for the first time on this survey an Eastern Wood Pewee singing at Tobacco Creek and another bird sited at East Park Boundary. The Acadian Flycatcher nest #2 at Tobacco Creek Seep was still active with a female flying onto the nest as I arrived. By now this bird should have young. The Blue Grosbeak nest at the Twin Falls and Pedernales River location has two 14 day old young in the nest. Photo above right. Both parents were actively feeding them. One Rufous-crowned Sparrow continues to sing at Twin Falls.

I walked upon a Rock Squirrel, near Tobacco Creek. It was in no hurry to hide so I was able to take some photos of it resting on a rock and taking a dust bath. Looks like I have one more week of surveying to follow-up on the two active nests. I hope to be back the Fourth of July.

Webberville Co. Park Nesting Prothonotary

Today I traveled to Webberville County Park for a first hand look at nesting habitat of a Prothonotary Warbler along the Colorado River. I was following up on a Texbirds report by Cullen Hanks of a nesting Prothonotary Warbler at the boat dock. This park has lots of tall Hackberry, Pecan, Cedar Elm, and Box Elder trees, including an abundance of Poison Ivy shrubs and vines. The trees and shrubs form a dense corridor of forest along the rivers edge. I began my search 9:30 A.M. looking over the sign posts, where the bird was reportedly nesting in the vicinity of the boat launch. I soon found out the young had already fledged the nest. I discovered the adult male actively singing NE of the boat launch site up until the time I left at 12 noon.
After about an hour of hearing the bird and only two glimpses of it flying across the river, I finally decided to hike into the forest, into the dense poison ivy underbrush, where I watched the male 25' away along the rivers edge. I observed this bird for an hour preen, sun its black tipped tail feathers, and feed itself and one fledgling, all within 15' of the ground and the waters edge.

Now that I have first hand evidence of Prothonotary Warbler habitat in central Texas I can say there is slim probability this species will nest along the Pedernales River in Pedernales Falls State Park. However, the data I am collecting falls into the category of a Breeding Bird Census which I intend to continue in 2009. I will also continue monitoring the nest boxes.

This year all ten nest boxes I put up at Pedernales Falls State Park, did not attract a single avian nester. However, at my home in Oak Hill I did have a Bewick's Wren nest with a 1-1/4" diameter opening similar to the nest boxes at the park. After contacting Chuck Jones, sanctuary manager at the Heard Wildlife Sanctuary, where a Prothonotary successfully nested last year, I learned the nest box opening should be 1-1/2" not the 1-1/4" I designed for.

So next year I plan to change the cavity entrance to 1-1/2" on all ten nest boxes. The only downfall for providing a larger entrance is this will allow the Brown-headed Cowbird to enter and lay its eggs. This years surveys I have reported the presence of cowbirds at all nest box locations.

To better identify this research project I will be changing the name of my blog site in 2009 to Pedernales BBC, (Breeding Bird Census) or something similar. Some of the nest boxes I intend to relocate lower to the river. If you have suggestions regarding this study please contact me at andres.susan@gmail.com.

Photos provided are of the sign posts at Webberville County Park. At this time I am not sure which post the Prothonotary Warbler actually nested in. All the posts have no cap on the top of the pole which is apparently where the bird entered and built its nest.

Birding the Summer Solstice

A waning gibbous moon and Jupiter greeted me on my drive to Pedernales Falls State Park this morning. At 5:30 A.M. at the primitive campground parking lot a pair of Screech Owls were calling. I biked the Wolf Mountain Trail to one of my survey sites following my moon shadow. There were quite a few Chuck-will's Widows calling and a few Common Nighthawks. At one point I startled a Chuck Will's Widow from a perch over hanging the trail. It took flight and flew five feet above me for about fifty feet. I had an avian escort flying silently like an over sized butterfly.
The dawn bird chorus at Tobacco Creek was so complete today it was hard to discern all but the loudest singing birds.
Acadian Flycatcher nest #2 is still active with an adult sitting tight at the Tobacco Creek Seep. Today is the first day I did not hear any Golden-cheeked Warblers sing, however I did see one individual along Twin Falls Creek. I suspect the nesting season may soon be over for this species.
There is a female Green Kingfisher hanging around Twin Falls. This individual could be nesting somewhere on the steep sloped ridges. The Blue Grosbeak nest at Twin Falls and the Pedernales River has two nestlings about six days old. (Photo to right)
I still hear a male Northern Parula warbler singing at Hackenburg Creek. I also heard for the first time there an Acadian Flycatcher singing its characteristic "Pizza" song!
The Summer Solstice is here (photo above) and breeding birds continue to take advantage of the long days in spite of the heat.

Blue Grosbeaks & Buntings

Blue Grosbeaks, Painted Buntings and Indigo Buntings were the most common songsters in the park today as summer brought nearly 100 degree temperatures. Today I found male Blue Grosbeaks singing at three sites. The Twin Falls & Pedernales River Blue Grosbeak nest still has the female sitting on two eggs. The song of this species is similar to the Painted Bunting but hoarser. Rufous-crowned Sparrows continue to be heard along Wolf Mountain Trail and one was recorded on the bluff at Twin Falls this morning.

Walking into Tobacco Creek I passed the Acadian Flycatcher nest #1. It appears the single nestling fledged. I heard the male singing in the draw. At Tobacco Creek Seep I discovered a second active Acadian Flycatcher nest. This nest is located on the same pecan tree limb overhanging the seep that the Black-chinned Hummmingbird nest was on. The hummingbird nest was predated on by a squirrel over a month ago. I watched the female Acadian Flycatcher fly into a leafy area so after my survey I investigated and found the female on the nest. Acadian Flycatcher nests appear to be located on the lower canopy of mature trees, thus quite visible, although they are the same size as the abundant ball mosses.

The seep at Tobacco Creek continues to bring fresh water dripping off old logs, (photo to the left). Today Red-eyed Vireo, Carolina Chickadees, the Acadian Flycatcher and Painted Buntings frequented this seep. The photo above is one of the easier climbs down to the Pedernales River at Tobacco Creek.

Bell's Vireo & Brown-headed Cowbird Egg

After verifying which egg was the Brown-headed Cowbird's I returned today to remove it from the Blue Grosbeak's nest. The cowbird's egg, pictured here, has speckling on it, and lucky for me the grosbeak's eggs are pale blue/white, an easy distinction in this case. Cowbird nestlings typically out-compete their smaller nest mates for food. This species has increased it's numbers in North America thanks to forest clearing creating more edge for it to search out host nests. So wherever there are threatened species nesting, cowbirds are being actively trapped and nests monitored to remove these eggs.

I started out this morning at the Bird Blind where I saw all the usual nesters, however, in the scrubby patch of land adjacent to the trail I heard a Bell's Vireo. Its song matched my recordings, very fast and bubbly like a House Wren. Later two Bell's Vireos came to the oak tree along the open edge of the bird blind. This is a new species for me in the park. It likes shrublands that include willows and streamsides.

I also verified that the Lark Sparrows are tending young in the nest. Viewing the nest from below, it is rather camouflaged to the human eye.

Acadian Flycatchers & Coral Snake

Overcast skies made today's survey more bearable. As summer settles in it appears the Acadian Flycatchers decided to move in as well. What I thought was one male on territory at Tobacco Creek turned out to be two, one at Tobacco Creek and the other at the Seep. I discovered an Acadian Flycatcher nest 25 feet up in a mature Hackberry tree along the Tobacco Creek ravine. It appears to be made of fine roots and is easy to mistake for a ball of moss hanging on tree branches. I saw the male feed one, almost grown, nestling. At East Park Boundary I found another male Acadian singing for the first time there.
On my hike into East Park Boundary I startled a Coral Snake along the side of the path. I watched it slither under a rock. The Coral Snake is very colorful and shiny. This is the second venomous snake I have found at Pedernales Falls State Park, the first being a Western Cottonmouth. I have yet to see a Rattle Snake here. At the mouth of Twin Falls Creek I took this photo of the Blue Grosbeak nest. The smaller speckled egg was laid by a Brown-headed Cowbird, a brood parasite.

Today I wrote up my notes at Pedernales Falls parking lot. There I watched fledged Cliff Swallows perch on a utility line. I also discovered a Lark Sparrow nest in the lowest most branch of a juniper tree near the restrooms. The parents did not tarry at the nest when delivering food. I do not know whether this behavior is normal or because of frequent human disturbance.

The photo above is a bat I found laying dead on the trail to Twin Falls. I guess this bat to be the Mexican Free-tail. One final note, I heard several Rufous-crowned Sparrows singing along the Wolf Mountain Trail. It appears these fellows enjoy the start of summer also.