Thursday, June 26, 2014

The Window Trail: Black-capped Vireo and Scott's Oriole

[Big Bend National Park, TX. June 2014]

The Window Trail is a 5.6 mile hike (round trip) from the Chisos Basin to the "Window" -- a dramatic rectangular opening in stone that marks the culmination of the trail:

The "Window" at the end of the Window Trail at Big Bend National Park
 
It is also possible to shorten the trail by a mile by picking it up at the Campground (as I did). At the start of the trail some familiar species were seen, but the prize was found near the end of the trail -- where the Window Trail forks with the Oak Spring trail: Black-capped Vireo.

Black-capped Vireo seen on the Window Trail at Big Bend National Park

Although the Black-capped Vireo is listed as "Endangered" by the US Fish and Wildlife Service, on a global basis, the IUCN has it listed one notch above -- at "Vulnerable". Unfortunately, it is no longer found in its historical range in the US (which included Kansas) and is now found only in the Edwards Plateau region in Texas and just 3 counties in Oklahoma. Brood parasitism and habitat loss are the chief culprits in its population decline. Sadly, the total global count of this handsome vireo is estimated to be no more than 5,3000 mature individuals.


Black-capped Vireo is our smallest vireo and visually also our most distinctive. Like many vireos, it shows olive and green on its upper parts while the undersides are white. The crown and face are black; the latter contrasting strongly with its prominent white spectacles. It is the only vireo that is sexually dimorphic with females substituting grey for the male's bold black.

Black-capped Vireo

In addition to the spectacular Black-capped Vireo, a Scott's Oriole was observed about a mile into the trail:

Scott's Oriole

Like other Orioles, Scott's too has a sweet and fluty song. This lemon-yellow and black Icterid is found only in the Southwest US.

Indigo Bunting

In addition to these remarkable species, more familiar ones were observed: Indigo Bunting and Blue Grosbeak.

The Indigo Bunting was the 3rd Bunting spied at Big Bend -- the others being Painted and Varied Buntings.

Blue Grosbeak

Blue Grosbeak is a widespread species at Big Bend -- looking like a bigger brother to the Indigo; however, the brown wingbars, darker blue coloration and stouter bill distinguish it readily from the  smaller Bunting.

Of our 13 vireo species, no species captures the imagination more so than the Black-capped Vireo. Although smallest in size, it exceeds its kindred species in every other dimension -- be it in song, color or rarity. And, while Big Bend affords many an avian treasure, the uniqueness of the little Black-capped Vireo remains in a league of its own.

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