Friends of Friedrich Wilderness Park Report
March 2, 2011

It is a combination of factors that makes Texas the prime destination for not only humans but also songbirds. One such songbird, the golden-cheeked warbler (Dendroica chrysoparia) (GCWA), has been known to fly over 1100 miles from its wintering grounds in Guatemala and other Central American countries to central Texas. Recently, the Natural Areas was lucky enough to have Mike Quinn come and talk with volunteers to shed more light on this subject. According to his thesis work at Texas A&M University on the “Abundance and distribution of potential arthropod prey species in a typical golden-cheeked warbler habitat” (2000), the GCWA, unlike some other species of warblers (Dendroica spp.) can be seen as a generalist in its feeding behavior. They opportunistically feed on whatever insects are available and common within their habitat (Quinn, M.A. 2011. Volunteer Appreciation Presentation). According to Quinn’s research, GCWA’s appear to arrive and leave during the peak arthropod season (Quinn 2011).

Of the four tree species commonly found in known GCWA habitat (cedar or Juniperus asheii, Texas red oak or Quercus buckleyi, live oak or Quercus virginiana, and cedar elm or Ulmus crassifolia), he found that these four different trees harbor different levels of dominant arthropod species at different times of the breeding season (Quinn 2000). Quinn (2000) found the greatest food source in the first part of the season, in March and early April, was on the Texas red oak (Q. buckleyi). From March to April, the caterpillar larvae (Lepidoptera) and the plant hoppers (Homoptera, Cixiidae) are the major food source found on these trees (Quinn 2000). From April to May, Quinn (2000) found that the live oak was the major food source, providing caterpillar larvae, treehoppers (Homoptera, Membracids), and crab spiders. From May to June and early July, the elms and the junipers were found to become an important food source providing large numbers of the juniper budworms and spiders (Quinn 2000). Although spiders were found to be available throughout much of the breeding season, it is the caterpillars that are sought out probably because they are easily digestible and highly nutritious, making it the perfect food for the hatchlings (Quinn 2011).

Quinn compared his findings in the field with the contents in the gizzards of GCWA’s made available for his study. While most arthropod numbers decrease with the season’s progression, spiders increase in number through the season. It was no surprise that the caterpillar larvae were the most abundant species in the gizzard, followed by spiders. Rainfall was correlated to abundance of caterpillars; lower rainfall produced lower abundance of caterpillars and higher rainfall produced higher levels of caterpillars. Spiders showed little or no relation to rainfall amounts. Another factor related to rainfall was that during drier years the black and white warbler, Mniotilta varia, a ground-nesting warbler, has been observed directly competing with the golden-cheeked warbler over territory and food; this was not observed during normal or wetter seasons.

So, for the golden-cheeked warbler, traveling great distances is not just about mild temperatures and prime nesting spots with great nesting material, it is about food. A high diversity and abundance of arthropods available throughout the season and the easily digestible and highly prized caterpillars make central Texas the prime location for this endangered songbird.

  Ecosystem Notes

Observed the following birds: chipping sparrows (Spizella passerina), robins (Turdus migratorius), ruby-crowned kinglet (Regulus calendula), western scrub jay (Aphelocoma californica), black-crested titmouse (Baeolophus atricristatus), Carolina chickadee (Poecile carolinensis), common raven (Corvus corax), hermit thrush (Catharus guttatus), spotted towhee (Pipilo maculatus), northern mockingbird (Mimus polyglottos), crested caracara (Ployborus plancus), greater roadrunner (Geococcyx californianus), yellow-bellied sapsucker (Sphyrapicus varius), ladder-backed woodpeckers (Picoides scalaris), Carolina wrens (Thryothorus ludovicianus), Bewick’s wrens (Thryomanes bewickii), Cooper’s hawk (Accipiter cooperii), American goldfinches (Spinus tristis), lesser goldfinches (Carduelis psaltria), eastern phoebe (Sayornis phoebe), northern cardinals (Cardinalis cardinalis), turkey vulture (Cathartes aura), and cedar waxwings (Bombycilla cedrorum).

Staff observed two bobcats (Lynx rufus) running across the road at Rancho Diana. A pair of red-shoulder hawks (Buteo lineatus) has been observed mating and perching together (and traditionally nest near the RD pond). Agarita (Mahonia trifoliolata), winter honeysuckle (Lonicera fragrantissima), anemones (Anemone edwardsiana and Anemone heterophylla), dutchman’s breeches (Thamnosma texana), elbow bush (Forestiera pubescens), redbuds (Cercis canadensis var. texensis) are all starting to bloom. The buckeyes (Aesculus spp.) are also starting to bud out. Spring is definitely in the air as evident by the Bewick’s wren, Carolina chickadees, northern cardianls and the phoebes all singing their songs.

  Volunteer Notes

Thanks to FOF Board for continuing support for annual volunteer appreciation event. It was a success with record volunteer attendance and a most informative presentation.

First Saturday Natural History Hikes
Jan 1, 2011 / Friedrich Park / No Walk
Feb5, 2011 / Eisenhower Park: Local History (very cold!) / 3 participants

Second Saturday Eisenhower Park
Jan 8, 2011 / Eisenhower Park Trees / 23 participants
Feb 12, 2011 / Eisenhower Park Fossils / 54 participants

Field Tours and Special Events (including Wild Week)
1 Field trip / 27 participants
Young Birders Club – 2 meetings / 15 participants
Thornton Elem Science Night / 42 participants
Explore classes: elem – birds, middle - fish / 78 participants
Project WILD trainings – 2 Eisenhower Park / 113 participants
Cub Scout geologist training / 8 participants

Volunteer Celebration – 27 volunteers and 3 guests attended this great event on February 10, 2011. Mike Quinn, TPWD entomologist, presented a very informative synopsis of his research into Hill Country insects and their relationship as a food source to golden cheeked warblers. A pot luck lunch, featuring tamales purchased by the Friends was a tasty end to the meeting.

January 27, 2011 / Field guides Birds/fish for Explore classes / 8 participants

Total Education participants in Nov and Dec: 305 youth and adults

  We are exploring the possibility of applying for a Brackenridge grant for a third year. Letters of intent to apply for a grant are due March 11, 2011. Cheryl Hamilton is seeking an additional school to add to the grant and will produce the letter to be approved by the Friends board.