Pedernales Falls State Park Prothonotary Warbler Nest Box Study: Western Cottonmouth & Birds Building Nests

Prothonotary Warbler Occurrence In Texas

Central Texas draws the western line for the Prothonotary Warbler range. This species occupies much of eastern North America up to the southern boarder of Ontario Canada.
Prothonotarys' nest in natural cavities but also readily use nest boxes located on or near water. Flooded swamps represent ideal habitat but they will also nest along rivers or small bodies of water.
In May 2007 I saw a brightly colored male Prothonotary Warbler at Pedernales Falls State Park bird blind. After some research I learned male birds have been seen building nests in neighboring counties to Blanco County. Further research revealed a pair of Prothonotary Warblers successfully nested at Heard Wildlife Sanctuary in McKinney, Texas.
In December 2007 I decided to undertake a nest box study at the park. January through February 2008 I hiked the entire Pedernales River and tributaries within park boundaries, in an effort to choose the best sites. Habitat selection proved a challenge do to high flood levels along the river.
Five sights were eventually selected where two nest boxes each were placed. Most boxes were attached to trees however two were attached to metal poles. These boxes were monitored from March through June 2008 on a weekly basis. A Breeding Bird Study was conducted at each nestbox location in 2008 and will be continued in 2009.

Saturday, April 26, 2008

Western Cottonmouth & Birds Building Nests

My first survey of the morning was at Twin Falls where a Western Cottonmouth Snake made an appearance swimming around the middle of the pool at 7:20 AM. It was just over a foot long, black with lighter rings of color. Its body was very thick in the middle and its head was triangular shaped and noticeably wider than its neck. This venomous snake swam leisurely in circles. A man from San Antonio and myself viewed this snake from the overlook with binoculars. The park manager says the Western Cottonmouth is somewhat common in the park around water.

Bird wise, it is the height of nesting season for birds in Central Texas. A White-eyed Vireo had 4 eggs in the nest at Tobacco Creek. I “pisshhed” in a female Golden-cheeked W arbler at East Park Boundary with nest material in her bill, and I saw a female Summer Tanager collecting cobwebs. A female Black & White Warbler was observed flying away with a caterpillar at Tobacco Creek, and finally, I found a Black-chinned Hummingbird nest above the seep at Tobacco Creek. The female was adding her final touches to an already lichen laden nest.

In the photo above you can see the nest, without bird, protruding from a broken off limb.
There is still no activity at any of the ten nest boxes. However migrants are still moving through as evidenced by the many Nashville Warblers heard and seen. Several Northern Parulas are still present and two new arrivals for the year were a Warbling Vireo and a Swainson's Thrush. I also watched and tried to photograph a Lark Sparrow from the Primitive Campground Parking Lot up on the hill. The photo to the right is a Lace Hedgehog Cactus correctly identified by Irwin Lightstone, president of the North Texas Cactus & Succulent Society. The Hedgehog Cactus is a small cactus species found in rocky open areas within the park.

The Pedernales River is 106 miles long originating 25 miles SE of Junction, Texas. It drains an area of the Edwards Plateau running west to east and empties into Lake Travis 10 miles west of Austin. With the volume of water the river moves, many natural and man-made materials get washed into it. Pictured here is a lounge chair pad hung up on a branch along a fast flowing portion of the Pedernales. Just a few weeks earlier I found a drowned dog hung up on the same stick. The Earth's rivers readily show how much humans have impacted the natural environment.