The Nature Writers of Texas

The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Sunday, July 25, 2004

Cliff and Cave Swallows are Commonplace
Ro Wauer, July 25, 2004, The Victoria Advocate, © 2004

These two look-alike swallows are commonplace throughout almost all of South Texas. That has not always been the case. Although cliff swallows have long utilized concrete overpasses and similar structures during their nesting season, cave swallows have become common only is recent years. Cave swallows, as their name implies, utilize shadowy nesting sites only, such as culverts and the underside of dark kiosks and similar small structures.

Besides their use of different nesting sites, the two species possess rather subtle differences in appearance. Although both are "square-tailed" swallows, at least in comparison with the longer, fork-tailed barn swallow, except for the voice, a positive identification may require careful study. Both possess a whitish belly, dark back and wings, and a buff-colored rump. Cliff swallows possess a dark rufous throat and whitish forehead, while cave swallows have a buff throat and rusty forehead. The voice of the two species often provides the easiest method of identification, especially when these birds are in flight. The call of the cliff swallow is usually described as a low "churr" and nasal "nyew." That of the cave swallow is a clear "weet" or pweet" or a soft, low-pitched "prrt."

Another interesting difference between the two species is their nests. Cliff swallows build the typical gourd-like structure from mud balls that they acquire from nearby puddles. Hundreds can often be found on the edge of concrete overpasses. Cave swallows build open mud nests, much like those of barn swallows, that they paste on rough edges.

Cliff swallows can be found throughout North America except for the southeastern corner of Arkansas, Alabama, Georgia, and Florida. They overwinter in South America. Cave swallows occur north of Mexico only in South Texas, southern New Mexico, and in extreme southern Florida, although nesting has been recorded throughout most of the High Country. They once were found only in natural cave-like sites in limestone area, but they learned that culverts and other man-made structures do just as well. Their principal requirement is a shadowy location. From the mid-1960s until about 1990, Carlsbad Caverns in southern New Mexico was the only place in the United States where cave swallows were known to nest. But by the turn of the century they had begun to expand their breeding grounds eastward in Texas.

One reason why cave swallows have been able to enlarge their range is that they have been able to roost in vacant cliff swallow nests during the wintertime when the original inhabitants are off on their winter vacations. Many populations are able to survive all winter in the original and temporary sites. That gives these new explorers a significant advantage each spring. They are able to nest earlier than they might otherwise if they had to migrate northward, and they therefore are able move northwards into new areas as post-nesting wanderers. It apparently has worked very well.

Sunday, July 11, 2004

30th Annual Butterfly Counts
Ro Wauer, July 11, 2004, The Victoria Advocate, © 2004

Since 1975, butterflies counts have been conducted all across North America in an attempt to acquire up-to-date information on butterfly distribution and abundance. Like Christmas Bird Counts that are held annually around Christmas time, butterfly counts are limited to 15-mile diameter areas during a single day. Butterfly counts can be scheduled between June 12 and July 25, although there is some flexibility for bad weather, like this year. The first of the local counts was undertaken at Goliad on July 2. Although only 29 counts were held the first year, 470 counts in 44 U.S. states and 5 Canadian provinces were conducted in 2003. Texas led with a total of 46 counts.

Bill Farnsworth, Paul Julian, and I tallied a total of 47 species on the Goliad count. Extremely high numbers (30-plus individuals) were recorded for pipevine swallowtails, pearl crescents, tawny emperors, sickle-winged skippers, common and tropical checkered-skippers, and southern skipperlings. Also abundant (10 to 29 individuals) were rounded metalmarks, bordered patches, and clouded, fiery, and eufala skippers. All of the other species tallied were less numerous. There were no surprises, as all of the species recorded were more-or-less expected. Goliad has a reputation in the butterfly community as being a good place to find a good variety of species. Over the years, a grand total of 107 species have been documented for Goliad.

The reason Goliad can boast about their butterfly abundance is that the area lies along the northern edge of the South Texas brushcountry and the southern edge of the eastern forest region. Species such as rounded metalmark, white peacock, coyote cloudywing, mazans scallopwing, and laviana and turk's-cap white-skippers are southern species that reach their northern limits in Goliad and adjacent counties. Silvery checkerspot is an example of a northern species that reaches the southern edge of its range in Goliad. Plus, the presence of the San Antonio River is also influential in that some butterfly species, especially summer/fall wanderers such as julia and zebra heliconians that often follow river corridors, occur there with some regularity.

Several more butterfly counts are scheduled within the region during the July count period, and anyone interested in participating is welcome. The dates and meeting locations (all starting at 9am) include: Palmetto State Park on July 9; meet at the HQ building. Choke Canyon State Park on July 12; meet as the South Unit entrance station. Indianola/Magic Ridge on July 15; meet at the entrance to Zimmerman Road along CO 316. Aransas National Wildlife Refuge on July 17; meet in front of the visitor center. Rockport on July 19; meet at the butterfly garden on Business 35.

All count data are submitted to the North American Butterfly Association (NABA) and published in an annual summary report. Although the original butterfly counts in 1975 were begun under the auspices of the Xerces Society, a national butterfly organization, NABA now has responsibility for the count coordination and publication. Count results and additional information about NABA is available at www.naba.org. Count forms can even be downloaded for anyone interested in starting their own count(s) at new locations.

The hobby of butterflying is one of our fastest growing hobbies. It attracts anyone interested in spending time in the outdoors. It takes less energy than birding, but has many of the same challenges. Since numerous excellent field guides have become available, the majority of species found in our yards and fields can be identified by sight. Close-focusing binoculars (those that focus to 6 feet or less) help considerably with identification in the field. Butterfly-watching can be great fun, whether undertaken in your our garden or along a trail or roadway in the wilds.