Sunday, June 22, 2014

Friedrich Wilderness Park: In Search of the Endangered Golden-cheeked Warbler

[Friedrich Wilderness Park, San Antonio, TX. June 2014]

Of our 54 warbler species, there is but one North American wood warbler that is classified as "Endangered": the Golden-cheeked Warbler. Only Bachman's Warbler which is listed as "Critical/Possibly Extinct" is listed at a higher degree of ecological risk (unfortunately, with no confirmed records since 1977, the worst is feared).

The Golden-cheeked Warbler is also the only avian species that nests exclusively in central Texas (the Edwards plateau region) and nowhere else in the world. Therefore, to see this rare species in Summer, a trip to suitable juniper/oak habitat in Texas is required. And, a small parcel of land that precisely fits this description is found in suburban San Antonio: Friedrich Wilderness Park.

Golden-cheeked Warbler seen at Friedrich Wilderness Park, San Antonio, TX

Identification of the Golden-cheeked is straightforward: think of it as a Black-throated Green Warbler with a few key differences:

Black-throated Green Warbler seen at Magee Marsh, May 2014

In this view both warblers show many similarities: white undersides, black throats, yellow face and an eye-stripe (they also both have black wings with 2 white wing-bars).

 Golden-cheeked Warbler -- back view

Black-throated Green -- back view

However, a back view of the two is useful when comparing the Black-throated Green with the Golden-cheeked as this shows clearly how they differ:
  • The Golden-cheeked has a black crown (compare to green in the Black-throated Green)
  • The Golden-cheeked has a black nape (compare to green in the Black-throated Green)
  • The Golden-cheeked has a black back (compare to green in the Black-throated Green)
  • The Golden-cheeked's eye-stripe is a bold black line (not green)
  • The cheeks of the Black-throated Green show a faint green crescent 
  • There is some faint yellow on the breast and vent on the Black-throated Green

Golden-cheeked Warbler seen at Friedrich Wilderness Park, San Antonio, TX

The primary reason for the decline in Golden-cheeked Warbler populations is habitat destruction in both its breeding grounds in Texas as well as its wintering sites in Central America.

Golden-cheeked Warbler seen at Friedrich Wilderness Park, San Antonio, TX

Golden-cheeked Warblers can be seen in Texas from March through August. Males are much more conspicuous in the earlier part of their breeding season when the best way to find them is by listening for their buzzy song.

Given this warbler's strict requirements for nesting habitat (juniper/oak canyonlands), it is restricted to just 13 counties in the Edwards Plateau region of Texas. This theme is similar to Kirtland's Warbler which is also extremely fussy about young jack pine breeding habitat in Michigan. However, unlike Kirtland's which has known to have bred in Ontario and Wisconsin, the Golden-cheeked is a breeder exclusive to Texas. This exclusivity coupled with its endangered status make for a compelling argument to add the striking Golden-cheeked Warbler to your birding experience.

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