In Search of the Colima Warbler

A Colima Warbler sips water from a pool in Boot Canyon

NPS/R. Negele

In late April, migratory birders flock to the Panther Junction Visitors Center. Outfitted in high-tech sportswear and draped with cameras and binoculars, the birders have one question: “Has the Colima Warbler been reported yet?”

Shown a photograph of the Colima Warbler, the non-birder rarely understands the obsession with a nondescript, grey bird. Sure, it’s got a patch of yellow on its rear and a dollop of rust on its crown, but basically, it’s grey. The Colima Warbler isn’t big. It’s not flashy. But it’s a Big Bend specialty.

 

First published image of a Colima Warbler.

Original painting by George Miksch Sutton.

Discovery of a Big Bend Specialty

In 1889, W.B. Richardson—a specimen collector for the American Museum of Natural History—discovered the Colima Warbler high in the Sierra Nevada de Colima in Mexico. For the next 39 years, ornithologists knew the bird existed, but that was about all they knew. The Colima Warbler remained a rare curiosity.

On a warm, July day in 1928, that changed. Dr. Frederick M. Gaige, entomologist, herpetologist, and director of the Museum of Zoology at the University of Michigan, collected a male Colima Warbler in the oak woodland of Boot Canyon, high in the Chisos Mountains. The discovery pushed the range of the Colima Warbler to its northernmost extent.

University of Michigan ornithologist Josselyn Van Tyne organized a second expedition to west Texas in the spring of 1932. Eight sturdy burros packed their field camp and supplies up the Juniper Canyon trail to Boot Canyon. At least one or two Colima Warblers sang from nearly every oak thicket.

Van Tyne was thrilled to find the birds. But his primary objective was to learn about the Colima Warbler’s nesting behavior. As he walked along a dry creek bed, a female warbler with nest material in her mouth flew by.

 

A Colima Warbler sits on her nest.

NPS Photo

A Nest is Found

“I stopped instantly and, remaining motionless, was greatly relieved to see the warbler continue undisturbed by my presence. In a moment she dropped to the ground and entered the nest which was on the sloping right bank of the stream about six feet back from the margin of the rocky stream bed. After working for about 20 seconds the warbler left the nest and flew down the stream bed… .” (Van Tyne 1936)

The nests are simple, symmetrical cups, woven from rootlets and fine grass material. Tucked under a rock, concealed by an arch of grasses, or covered by dry leaves, Colima Warbler nests are well-hidden from predators and observers. Finding active, nesting birds convinced Van Tyne that the Colima Warblers weren’t stray birds. The oak, maple, and Arizona cypress woodlands of the high Chisos was prime breeding territory.

The population of Colima Warblers in Big Bend is relatively stable. Every 5 years, since 1967, up to 35 citizen scientists shoulder their packs and spread out in territories from Green Gulch to Boot Canyon to search for warblers. Numbers fluctuate, but the Colimas are still there, year after year.

5 Tips for a Successful Colima Warbler Search

Ornithologists have searched for the Colima Warbler in other sky islands of the southwest. But so far, the only place to see this bird is in Big Bend National Park. Here are some tips for adding the Colima Warbler to your life list:

1. Colima Warblers are migratory birds. They usually start to arrive in late April and will be gone by August.
2. Be prepared to hike. You may be lucky enough to see a Colima Warbler on the Lost Mine Trail or perhaps in the Chisos Basin Campground. If finding the bird is your goal, though, hike up to Boot Canyon or along the Laguna Meadows trail. That’s 4.5 miles of steep, rugged terrain. Take plenty of water and plan on making a day of it. If you can, reserve a campsite and stay overnight in the high country.
3. Become familiar with the Colima’s song. You’ll hear the birds long before you actually see one. Prepare ahead of time and don’t play a recording of the song when you’re in the bird’s territory. This is considered a threat by living birds and may drive them off their nest.
4. Make sure you can recognize an oak tree. Colima warblers are ground-nesters, but they forage in oak trees. Knowing this will significantly increase your chances of seeing one.
5. If you hear singing Colima warblers and you’re near water, have a seat and settle in. Colima’s will come to water, especially if there’s an oak tree nearby. Watch as they work their way down a limb and drop into the pool for a quick bath or sip of water.

Citation

Van Tyne, J. 1936. The Discovery of the Nest of the Colima Warbler (Vermivora crissalis). Ann Arbor: University of Michigan Museum of Zoology Miscellaneous Publications No. 33.

 

Bird Information

• 

  Seasons and Specialties

  What is the best time of year for birding in Big Bend? It depends on what bird you are looking for!

• 

  Birding Hotspots

  Discover the best locations in the park for birding!

• 

  Get Involved

  Find out how you can contribute to our knowledge of birds!