Author Archives: Elisa Lewis

Insect Oasis

Posted by Elisa Lewis
Portrait of a Hermit Thrush on the beach at Galveston, Texas
This Hermit Thrush emerged from a patch of cane along the eastern tip of Galveston Island.

I was a bit surprised to see this Hermit Thrush hop out of the cane patch I was hiding in last weekend on the east end of Galveston Island. I’ve only seen Hermit Thrushes in their typical habitat—the understory of coniferous or deciduous forests. Instead of rummaging through moist leaf litter, this little one hunted a sea of sand punctuated by 12-foot-tall bamboo stalks. Was it lost?  I don’t think so. . . . It was keeping good company. In the course of less than an hour, I observed an Eastern Phoebe and a Ruby-crowned Kinglet find a variety of tasty insects and spiders. Also, just the week before, I spotted a Swamp Sparrow and a female Indigo Bunting and Redstart in the same small patch. Hmmmmmm.

Ruby-crowned Kinglet hunting at Galveston Island, Texas
I observed this Ruby-crowned Kinglet fishing spiders out of nooks and crannies.
Eastern Phoebe perched on giant river cane on Galveston Island, Texas
I spotted this Eastern Phoebe using cane as a hunting perch.

 

 

 

 

 

 

 

 

 

 

 

 

Questioning how this cane patch could be an insect-rich oasis for migrating and wintering birds led to a little research project (as do many of our outings). I had always assumed these patches of cane scattered on the beach and coastal waterways were foreign and invasive. Since non-natives don’t typically support complex ecosystems, I initially turned my nose up at them. (Invasive plant species often provide cover and water but do not support a wide diversity of prey species required for a complex food web.) As it turns out, Arundinaria, our only native bamboo, is endemic to the eastern half of the US.

With newfound respect, I look forward to a much more enlightened investigation of these remnant coastal bamboo “forests.” If you decide to venture into the cane, don’t forget your snake boots!

© 2012 Elisa D. Lewis. All rights reserved. No text or images may be duplicated or distributed without permission.

Conspicuous Consumption?

Posted by Elisa Lewis
Black and yellow garden spider with grasshopper
This female Argiope aurantia (aka, the black and yellow garden spider or writing spider) easily subdues a grasshopper that launched itself into her web after an unlucky jump.

While most visitors to Brazos Bend State Park keep an eye trained on the water for alligators, I seek the park’s lesser championed predators suspended in plain sight along swampy summer paths. But it wasn’t until I spotted this Argiope tending to her prey late last month that I realized we had missed the usual spider-o-rama fest that normally occurs late each summer and early fall – or did it miss us? A conversation with one of the park’s excellent naturalists confirmed that this has been a bad year for the conspicuous black and yellow spiders that typically drape the pathways with their giant webs. Two species’ females with this general description are readily observed–Argiope aurantia pictured above, and Nephila clavipes the golden silk orb weaver or banana spider, shown below.

golden-silk-spider-banana-spider-golden-silk-orb-weaver
The golden silk spider is known for its gold-colored silk that the female spins into webs reaching up to 3 feet in diameter. Visitors to Brazos Bend State Park can typically see large concentrations of these spiders along paths bordering swamps from late summer to early fall.

Why would spider populations plummet in one year’s time?

Could it be that last year’s drought put these spiders (most likely prey of last resort given their warning coloration and the danger of entanglement) in the precarious position of being the most conspicuous food source around for hungry, desperate birds? Perhaps the effect was compounded by a collapse of the arthropod food web?

In any case, we’ll be watching spider populations next season.

Last Brood of the Moorhens?

Posted by Elisa Lewis

Common Moorhens may raise up to three broods per breeding season, especially in their southern range, but I was a bit surprised to find a pair of Moorhens with young chicks on the autumnal equinox, September 22, 2012. It got me thinking that these chicks, seen near the end of September, are most likely the last brood of the season at Brazos Bend State Park, Texas. Day-length, or photoperiod, along with temperature changes, govern many seasonal changes in animals including changes in the coloration of fur/feathers, hibernation, migration, and mating behavior. Here, along the gulf coast, our seasonal changes are gradual – permitting longer growing seasons and, happily, longer baby bird watching as well!

Common Moorhen with chick exhibiting begging behavior.
With their bald patches and what look like bad hair-plugs, Common Moorhen chicks could easily win a “so-ugly-they’re-cute” contest. This little one is begging for food by “flapping” its stubby wings.  Moorhens with young can be found throughout the long, hot summer at Brazos Bend State Park, Texas.

Fly vs. Fly

Posted by Elisa Lewis

When the sun is high in the sky and the light isn’t conducive for bird photography, I like to bust out the macro lens and look for smaller wonders. I found this robber fly taking a break among the scrubby beach vegetation while its neurotoxic, proteolytic saliva paralyzes and chemically digests the insides of its current victim. Charming. It’s a good thing (for us) that these flying assassins exclusively prey upon arthropods – mostly other insects at that.

Robber fly predator with fly prey
Robber flies frequently make meals of other flies. Galveston Island (East End), Big Reef Nature Park, Texas