NABA South Texas Home Page

Why so many fall 2004 new U.S. butterfly records 
in South Texas?

I attribute the plethora new records to the following synergistic effects:

1) An order of magnitude more butterfliers looking on a daily basis than traditional lepidopterists who usually only visit the Rio Grande Valley on an occasional basis. Probably every single fair weather day from mid September to mid April has one or more people checking known butterfly hotspots in Hidalgo Co., and less frequently in adjacent Starr & Cameron Counties. During the height of the butterfly season, roughly from mid October to mid December, 10, 20, or more people check Hidalgo County's known hotspots daily.

2) Knowledge of people looking has greatly increased. People are noticing and (mostly) correctly identifying the subtly different species with great regularity. Glassberg's field guides got the field-identification ball rolling with excellent photos of living butterflies. Recently published guides covering the RGV such as Bordelon & Knudson (2002), Brock & Kaufman (2003), and Garwood & Lehman (2004) have been instrumental in education people.

3) Digital cameras and personal websites. With the fairly easy to use "digicams," people can shoot more pix and discard later. Photographers can post their images to personal websites at the end of the day thus alerting others about what's being seen and where. (I try to gather in the more important records from the various personal websites and cross-post them on the NABA site as something of a "central depository.")

4) There's more butterfly habitat being created almost on a monthly basis. The first prominent butterfly garden planted in the Valley was at Santa Ana NWR visitor center (in 1999?). That one garden I think made a very big impression on people across the Valley. Visitors were able to get out of their cars and immediately see large numbers of common to rare butterflies. Since then the number of backyard gardens has grown. Plus every park, refuge, and nature center that I know of in the RGV now has added additional butterfly host and nectar plants. Our knowledge of which plants "work" in the Valley is pretty good. Probably the single best nectar plant is Eupatorium odoratum. This plant, if watered, grows remarkably fast. Once you put in a couple of "Eups", you quickly get a whole lot more volunteer plants.

5) The amount of rains the Valley has been getting over the past two years is above average. This is a very significant factor. The off the charts number of new records in the late 60's and early 70's was also a very wet period induced by several hurricanes through the area. When I was living in the Valley in the late 1990's the region was in the grips of a significant prolonged drought. There wasn't much rare butterfly activity outside the high season of October to November. (There were also fewer people looking, less habitat, fewer resources, etc. then.)

6) Communication, the Internet and cell phones. When something really rare shows up, people can call others directly cell phone to cell phone from the field. In this way, multiple Mexican butterfly strays are often seen as they frequently emigrate north in something of a wave. TX-Butterfly listserv and email in general allows people just back from the field to consult others across the continent for near immediate assistance. Websites disseminating information relevant to the Valley include: NABA-SoTX, Neotropical Butterflies, USGS, and recently the Guanacaste database site.

This word-of-mouth can and does travel far and wide. When I was down last October for the Texas Butterfly Festival, I met many people who already knew what was being seen before they arrived. The annual (long after-the-fact) Season Summary of the Lepidopterists' Society with its long list of scientific names sans corresponding common names and with no more than one or two black and white photos doesn't generate the excitement among the masses that an email shouting NEW US RECORD!!! can. Such an email with a web link to one or more color photos offering proof of the record's veracity induces the kind of excitement causes people to want to buy plane tickets...

7) The Texas Butterfly Festival. This festival is advertised nationally and gets a lot of local press as well. We regularly have prominent lepidopterists such as Drs. Pyle, Opler, Glassberg, Acorn, the Tveten's, etc. telling everyone down there how unique the Valley is from a diversity stand point. People that come down and see for themselves take their stories and their photos back home. The festival's field trips show hundreds of people specifically where the hotspots are and ID a large percentage of the butterflies on the wing at the time. A number of people stay in the Valley beyond the end of the festival and continue to butterfly. The very popular Rio Grande Valley Birding Festival hosted by Harlingen also creates butterfly buzz as mid-November is usually still quite good butterflying. These festivals reinforce the need for more habitat.

8) Global Warming effects (e.g. Crozier 2004) on the Tamaulipan butterfly fauna may also be a contributing factor. While there are some 300 species of butterflies recorded from the Lower Rio Grande Valley, nearly twice that many are known from the adjacent Mexican state of Tamaulipas, which has the highest biodiversity of Mexico's northern-most states (Luis et al, 2003).

Mike Quinn, Austin, Texas


Bordelon, C. & E. Knudson., 2002. Illustrated Checklist of the Lepidoptera of the Lower Rio Grande Valley, Part 1 : Butterflies. Houston, Privately printed. viii, 84 pp. 20 plates.

Brock, J.P. & K. Kaufman. 2003. Focus Guide to Butterflies of North AmericaHoughton Mifflin Co., Boston. 384 pp. 

Crozier, L. 2004. Warmer Winters Drive Butterfly Range Expansion by Increasing Survivorship. Ecology 85(1):231-241.

Garwood, K. & R. Lehman. 2004. Butterflies of Mexico: Tamaulipas, Nuevo Leon, San Luis Potosi  Privately Published. 97 color plates, approx. 750 images.

Glassberg, J. 1999. Butterflies Through Binoculars, The East. Oxford University Press, Oxford. 400 pp.

Glassberg, J. 2001. Butterflies through Binoculars, The West. Oxford Univ. Press., New York. 352 pp. 

Luis, A.M., J.B. Llorente, I.F. Vargas & A.D. Warren. 2003. Biodiversity and biogeography of Mexican butterflies (Lepidoptera: Papilionoidea and Hesperioidea). Proceedings of the Entomological Society of Washington 105(1):209-224.


16 Dec 2004 / Main South Texas Page