Butterflies!

In the last post, I described the first half of our trip to the Lower Rio Grande Valley (LRGV). We spent another 9 days in the field before returning to El Paso for New Years. Fortunately, the weather improved somewhat, and we had many more opportunities to photograph butterflies than in the first half of the trip. We spent two days each at Sabal Palm Sanctuary, Santa Ana National Wildlife Refuge, the National Butterfly Center, and paddling on the Rio Grande; Christmas was a short day at Estero Llano Grande.

Sabal Palm Sanctuary protects the only significant grove of Sabal Palms in the U.S.; and this species is the only native palm in the LRGV. The sanctuary is located in a no-man’s-land between the border fence and the actual Mexican border in the Rio Grande, and it was inaccessible for a few years because of security concerns. The Forest Trail probably has the lushest native habitat in the LRGV; it took about an hour for us to cover the first 50 yards of trail, because of the number of interesting subtropical plants. One species we found, Slender Passion Flower, occurs nowhere else in the U.S. Over the course of two days we identified 17 native plants that were new to us, but of particular significance, these included three new families of vascular plants. So we have now seen 212 out of 252 families in North America, and need another 25 to reach our long-tern goal of 95%.

On the second day in Sabal Palms we had a few hours of sunshine when we first arrived, during which the butterflies were good (they generally start flying in numbers when the temperature exceeds 70F, provided it is not too rainy or windy). The most exciting species were Red-bordered Pixie and a close Malachite. Nice birds at the sanctuary included Olive Sparrow and Black-throated Green Warbler.

The National Butterfly Center in Mission, Texas, is a 100-acre property on the river, a few miles west of Bentsen. Formerly agricultural land, for over a decade it has been extensively replanted with natives to encourage use by butterflies, and the visitors’ center opened about 6 years ago. Despite its short history, it has become one of the best sites for butterflies in the U.S., with over 200 species having been recorded there. For reference, there are about 730 species known in North America (north of the Mexican border), of which about 280 occur in the LRGV — and about 150 of these are rarely found elsewhere in the U.S.

The National Butterfly Center is a concentration point for people who pursue butterflies with the same intensity as birders pursue birds (and, indeed, quite a few are “birders gone bad”). As soon as we walked out onto the grounds, a helpful gentleman told us we should immediately go to a bait log (covered with honey, fruit, etc.) to see a rare Blomfild’s Beauty, a Mexican vagrant recorded in the U.S. about once every five years. This we found, and soon after we converged with others towards where we heard a shout and were shown a thumbnail-sized Telea Hairstreak, another great rarity. As unusual species were found, phone calls were made and texts sent to alert everyone. On that first day we saw 29 species of butterflies, about half of them new for us!

The second day we visited we decided to do a single-location butterfly “big day”, even though we were just beginners. It was a blast! We finished with 39 species, nearly all of which we found ourselves. Coincidentally, that’s just about the same as my whole butterfly life list when we arrived in the LRGV! Serious butterfly aficionados have (barely) broken 100 species in a day in the LRGV (visiting multiple locations), so this is only a notable total for us personally, as novices. But it will be fun to see if we can beat it in the future.

One of our canoe trips started at Salineno, like the one mentioned last time, but this time we went downstream instead. Highlights of this paddle were Audubon’s Oriole and Alligator Gar. The gar is a massive, primitive fish that we were able to see well several times from the canoe. The record length for this species is around 7 feet, but ours were “only” about half that long.

Our other canoe trip started at Anzalduas County Park, from which we paddled upstream on the Rio Grande to get into an otherwise inaccessible body of water, which looked interesting in Google satellite photos. We saw Neotropic Cormorant here, as well as a new tree species, Willow-leaved Buttonwood, which is hard to find in the U.S. We saw a number of Muscovy Ducks here on the Rio Grande (and a few elsewhere, for a total of about a dozen), but unfortunately all gave indications (plumage or behavior) of deriving at least in part from domesticated birds, rather than being truly wild wanderers from the swamps of Mexico. One other incident of note that day — while driving, we came on a field that was being actively disked by a tractor, and it contained 9 White-tailed Hawks, 6 Crested Caracaras, and 6 Long-billed Curlews, watching for insects and mammals flushed by the tractor — a fine assemblage!

In the two days at Santa Ana, we hiked most of the more remote trails in the park, which pass through marvelous native thorn scrub habitat. Highlights included Roseate Skimmer (a magenta dragonfly!), Ruthven’s Whipsnake (uncommon), and Laredo Striped Whiptail (a colorful lizard).

All told, in this 19-day visit, we saw 101 new species toward our goal of 10,000, bringing our total to 8626. These new species included 52 plants, 42 butterflies, 3 dragonflies, 2 reptiles, a fish, and the bizarre Mexican Unicorn Mantis, a predatory insect that caught a small butterfly while we watched.

Happy New Year!