Evolution and Ecology

Firebird

Posted December 9, 2012 by Elisa Lewis

Vermilion Flycatchers are some of our most anticipated fall visitors along the Texas Gulf Coast. Visiting populations migrate east, not south, for the winter bringing the colors of the West with them (their U.S. breeding range includes CA, NV, AZ, NM, and western and central TX). This flycatcher’s scientific name says it all – Pyrocephalus rubinus (a reference to the spectacular coloration of the male). As if the generic name, Pyrocephalus, or “fire head,” wasn’t enough, the specific name, rubinus, emphasizes the redness of the bird. One of a few types of so-called “firebirds,” the Vermilion Flycatcher is not only eye-catching, but is energetic and exciting to watch, just like other flycatcher species. Three vermilions – a male, female, and juvenile male – thoroughly captivated us last weekend at Anahuac National Wildlife Refuge (NWR) headquarters.

This view of the male highlights why this bird is nicknamed “firebird.” Notice the subtle orange-red color variation and the crown feathers–like licking flames. I did not alter the image other than cropping.

The female provided the best viewing opportunity as she perched within 12-15 feet of me. I had the luxury of settling in and studying her behavior for almost an hour. Between bouts of preening, she tracked insects as they flew by – sometimes it appeared as if she were watching a tennis match. Why wasn’t she going after them? Then, all of a sudden, she took off and grabbed one out of the air. What was it about that last fly by? Was it the insects’ speed, trajectory, size, or proximity that finally made the difference? Or some combination? And then again: track, track, track, go! It reminded me of playing duck, duck, goose as a child. As I went around the circle, patting the heads of my classmates, I was calculating . . . who could I outrun?

Was the flycatcher calculating? The literature seems to suggest that the Vermilion Flycatcher always gets his/her prey. If the initial attack is unsuccessful, the prey “may be pursued in an erratic acrobatic chase until capture” (Wolf and Jones 2000, 5). Though the research sample is small, it does makes sense from an evolutionary perspective. Individuals most efficient (or dogged if necessary) at capturing prey (we could call it flight/eye coordination), will most likely live the longest and leave the greatest numbers of offspring edging the overall average toward a more and more efficiently predatory population.

When watching flycatchers, one can be excused for anthropomorphizing. They often cock their heads with apparent curiosity, and just about ooze charm. Flycatchers seem to delight in taking a particularly big or juicy bug–male Vermilion Flycatchers have been seen presenting potential mates with large, showy gifts–like butterflies. That would be an awesome image indeed — the handoff of a nuptial gift of an insect gem from a male Vermilion Flycatcher to his lady. Stay tuned! I will be watching for it next season in their breeding territory.

Female Vermillion Flycatcher at Anahuac NWR, Texas — This female Vermilion Flycatcher was hunting in open grassy areas on the edge of a dense thicket at Anahuac NWR. Notice the faint wash of red on her crown–not all female Vermilion Flycatchers show this extra blush of color.

References

Wolf, B.O., and S.L. Jones. 2000. Vermilion Flycatcher (Pyrocephalus rubinus). In The Birds of North America, No. 484 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, P.A.

Birding the Spectacular Thickets of the Texas Gulf Coast in Fall

Posted December 2, 2012 by Chris Cunningham

Thicket at Anahuac NWR — A thicket at Anahuac National Wildlife Refuge (NWR), Texas Gulf Coast. This densely vegetated area was hopping with Yellow-rumped Warblers, Eastern Phoebes, and Swamp Sparrows.

Fall is an incredible time to bird the Texas Gulf Coast: migrants are returning or passing through, the plants are changing colors, mornings are cool, and the bugs are on the way out–but not all the way out, lest our beloved insect-eaters keep moving! Some of the most exciting environments to bird at this time of year are the densely-tangled thickets near the numerous waterways of the region. We especially love to bird Brazos Bend State Park, Sabine Woods, and Anahuac NWR (both the Skillern and Main tracts) at this time of year. Thickets in these areas are challenging for photography most of the year, but in fall are literally hopping in places with insectivorous birds.

Fall shedding of leaves leads to an opening up of possibilities for photography: the dense (often frustrating) greenery of summer, sometimes making it impossible to photograph shy, secretive thicket species is slowly breaking up. Splashes of color now punctuate images, and the amber and reddish glow of autumnal mornings and evenings tint backgrounds.

Common Yellowthroat at Pilant Lake, Brazos Bend State Park, Texas — *Young Common Yellowthroat in Fall Morning Light*. Photo taken at Pilant Lake, Brazos Bend State Park.

The explosion of insect-eaters during the fall migration is a reminder that the mass migrations of birds are all about the flow of solar energy. As the supply of warm-weather prey dwindles in the northern latitudes the bug-eaters must move south in search of their (mostly) ectothermic prey. The Texas Gulf Coast stays warm enough throughout the winter to keep a supply of insects large enough to support a large population of flycatchers, especially Eastern Phoebes, that can be seen perched on branches over water or open grassy areas. They flit down, grab an insect and then return to their perch to dine. A spectacular sight to behold is a Phoebe grabbing a butterfly on the wing. Surprisingly, they ingest the whole insect, wings and all. One wonders how much nutritional value a butterfly wing has, though. Vermilion Flycatchers exhibit similar behavior in these thicket environments, but a discussion of these beautiful little birds must await Elisa’s next post!

Myrtle Warbler at Anahuac NWR, Texas — *Audubon’s Warbler Against Fall Colors* at Anahuac NWR. This locality is in East Texas, a place where one doesn’t normally see Audubon’s Warblers. Perhaps this bird is a Myrtle-Audubon’s hybrid? Shot hand-held Canon 7D EOS with 300mm f/4L IS (+1.4x TC).

Why Birders Should Care About the Global Amphibian Crisis

Posted November 22, 2012 by Chris Cunningham

Little Blue Heron with tadpole at Brazos Bend State Park, Texas — *Little Blue Heron with Tadpole* at Brazos Bend State Park, Texas Gulf Coast.

Over the past several decades the diversity and abundance of Amphibia have declined precipitously: estimates for the amphibian extinction rate range from tens to tens of thousands of times the typical background rate of species loss. Despite conservation efforts (Amphibian Ark) and some publicity, most people I speak to are completely unaware of this catastrophic decline. Over the past decade or so, it has become clear that there are several major causes. The most important appears to be habitat loss. As freshwater swamps and marshes are drained to build the endless suburban sprawl of tract housing, and forests are bulldozed into the chippers, amphibian habitats are dwindling. Acidification of lakes and ponds, other forms of pollution, and an infectious fungal disease (chytridiomycosis), are also implicated.

American Bullfrog at Brazos Bend State Park, Texas — *American Bullfrog (Rana catesbiana) at Brazos Bend State Park, Texas.* American Bullfrogs are an abundant food source for waders along the Texas Gulf Coast. Luckily, bullfrogs appear to have resistance to chytridiomycosis.

Many think that the reason amphibians have been among the hardest hit groups in the current anthropogenic mass extinction event (the Holocene mass extinction) is because these animals have aquatic larval stages and a terrestrial or amphibious adult stage, and can be negatively impacted by changes in both the aquatic and terrestrial environments. The process of metamorphosis, which typically occurs in an aquatic environment (or at least an aqueous one–think about the bromeliad treefrog!), is biochemically sensitive. For these reasons, some refer to amphibians as the “canaries in the coal mine” of ecosystems.

Olympic Peninsula, Washington — *Northern Red-legged Frog* (*Rana aurora*) at Olympic National Park, Washington. In some places, the ground-cover vegetation of the temperate rain forests of the Pacific Northwest is alive with amphibians.

As a photographer, one of my favorite subjects is hunting waders: please see Stalking the Hunters. Along with fish, crawfish, and aquatic insects, amphibians (primarily frogs and tadpoles, and to a lesser extent salamanders) form a staple of the wader diet. Other predatory birds, Loggerhead Shrikes, for example, also eat amphibians. Shrikes are fascinating birds known to kill their prey by impaling it on sharp objects, usually thorns. On one, and only one, occasion we heard what we thought was a frog call coming from above. We looked up to notice a Loggerhead Shrike on wire over a frog-filled bayou. Was this a simple case of mimicry? Or deception—trying to get a frog to divulge its location? Research turned up no mention of Loggerheads making frog calls. Shrikes are known to deceive each other away from kills with frightening false alarm calls–so they’re not above trickery. The Asian Rufous-backed Shrike is an accomplished mimic, and, of course, the Northern Mockingbird is known to mimic frog calls, but a Loggerhead Shrike? We will continue to keep our eyes and ears peeled for this phenomenon. If we heard what what we think we heard, we hope the time a Shike’s frog-call goes unanswered never comes.

Shrike-impaled Green Tree Frog on rose thorn, Sabine Woods, Texas — *Green Tree Frog (Hyla cinerea) on Rose Thorn.* Elisa captured this macabre image of a Loggerhead Shrike-impaled tree frog at Sabine Woods, Texas Gulf Coast. The shrike had just killed this frog and a mouse, whose decapitated body was impaled on some more rose thorns and whose head was impaled on some nearby barbed wire. As soon as Elisa finished the shoot and walked away, the shrike returned and reclaimed the mouse’s head.

Insect Oasis

Posted November 4, 2012 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!

Fall and Winter Fruits . . . Ah, the Irony. . . .

Posted October 13, 2012 by Chris Cunningham

Knowledge is knowing that a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad. –Brian O’Driscoll

One of the treats of birding in the cooler months is watching for birds enjoying the many types of conspicuous fruits and berries that can be found in the woodland habitats of the Texas Gulf Coast. Yaupon holly (Ilex vomitoria), greenbriar, and agarita are just a few of the many examples of native plants bearing brightly-colored berries during fall and winter that are popular with birds. As a photographer I always have an eye out for a Cedar Waxwing, American Robin, Northern Mockingbird, or Northern Cardinal with a rosy-ripe and juicy berry in its beak.

As a novice field botanist, I often photograph newly encountered fruit-bearing plants with the hopes of later identifying them. It soon becomes evident, however, that the landscape is dotted with exotic fruit-bearing plants from around the globe–escapees from gardens, seeds sown through the digestive tracts of birds or mammals. Sometimes they are identifiable, sometimes not. I’m sure some of the species that I find impossible to identify are, to landscapers and nurserymen, commonly-known, popular garden varieties–from South America, the Caribbean, or that great cradle of Angiosperm evolution, Northern China.

House-Finch-on-Chinese-tallow-CCunningham — *A House Finch Eats Chinese Tallow Fruit.* Federal biologists imported Chinese tallow into the U.S. in 1905. This plant is now taking over many forests of the South. Photo taken in Houston, Texas. Canon EOS 7D/500mm f/4L IS (+1.4x TC).

It might be tempting to suppose that these introduced species may be harmless or even helpful to birds, given that they produce edible fruits. Species of Pyracantha, for example, are commonly encountered invasives that produce copious amounts of bird-friendly fruit–and birds are implicated in the spread of these Eurasian plants. The Chinese tallow tree is another common invasive. Chinese tallow may be the greatest challenge, after man himself, to the warm native forests of North America. About 23% of all trees in the Houston area are now Chinese tallows.

In contrast to many of the natives, some of these foreign plants seem strangely sterile: not an arthropod of any kind is to be seen on them. As these foreign invaders have proliferated, robbing pollinators and insectivorous birds, displacing and replacing native ecological equivalents, songbird numbers have declined an estimated 40% in my lifetime. Of course, it’s hard to prove which aspect of humankind’s activities–chopping, plowing, spraying, shooting, paving, or planting foreign invasives has been most disastrous for our birds–but to me it doesn’t really matter–it’s all of a piece. Homo sapiens sapiens, the Yersinia pestis, of the planet’s biosphere marches unrelentingly on . . . We are, it seems, in the midst of an anthropogenic mass extinction event. And the Dodo, Ivory-billed Woodpecker, Passenger Pigeon, Carolina Parakeet and Hawai’i Mamo bore witness. . . .

Pyracantha sp,, in Houston, Texas — *Pyracantha*, a Eurasian invasive, is displacing native plants. The brightly-colored berries are attractive to birds that disperse the seeds. Photo taken in Houston, Texas. High-speed synchronized flash.

Conspicuous Consumption?

Posted October 7, 2012 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 September 29, 2012 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.

See Early Fall Migrants on the Texas Gulf Coast (and don’t forget your sunscreen and bug repellent)!

Posted September 22, 2012 by Chris Cunningham

Elisa and I have been out trying to catch glimpses of the early fall migrants, especially songbirds, along the Texas Gulf Coast at places like Sabine Woods, Brazos Bend State Park, and Anahuac National Wildlife Refuge (ANWR) . . . and we have been paying the price. Until the first real norther arrives, the heat, humidity, and bugs rule. It makes sense that the larger the number of insects, the larger the number of migratory insectivorous songbirds that one would find at any given locale along the Texas Gulf Coast. This is the general pattern that we have observed: Brazos Bend is generally the least buggy (almost anomalously so) of any of the major birding spots we frequent, and we see the fewest insectivorous songbirds there. Of course, Brazos Bend is farther from the coast than the other localities, so it not a migrant trap. But Brazos Bend has so few flying insects, biting and otherwise, that it has caused me speculate about the cause(s). There is plenty of standing water for mosquito reproduction, but there are also large numbers of deer in the park, and large ungulate populations have been shown to negatively impact songbird populations due to grazing on insect and bird food plants (reference Aldo Leopold). On the other hand, the bugs at Sabine Woods and ANWR can be brutal. Today at ANWR (Skillern Tract) the deer flies and mosquitos literally chased us out of the marsh! Bugs are food for birds and food for thought.

Black-throated Green Warbler portrait at Anahuac National Wildlife Refuge, Texas — *Black-throated Green Warbler on Hackberry Branch.* Note the insect body parts on the tip of the beak. I think I was being eaten alive by the very bugs this beauty was dining upon. Skillern Tract, ANWR, Texas Gulf Coast.

Yellow Warbler on Oak branch at Sabine Woods, Texas — *A Young Yellow Warbler* perches on an oak branch at Sabine Woods, Texas Gulf Coast. A glimpse of paradise in a sweltering purgatory of biting insect nasties.

Fly vs. Fly

Posted September 1, 2012 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

Instinctive Behavior in a Green Heron, Brazos Bend State Park, Texas

Posted August 26, 2012 by Chris Cunningham

What a book a devil’s chaplain might write on the clumsy, wasteful, blundering, low, and horribly cruel work of nature! –Charles Darwin

Usually when one sees a wader grab a prey item, the prey is subdued, perhaps by a few pecks, then manipulated into position and swallowed. Today at Brazos Bend State Park, however, I observed a Green Heron grab a large American Bullfrog tadpole. The bird picked up and then dropped the tadpole a few times after intermittently pecking it. Finally the bird discarded the tadpole and walked away. I thought this strange given that waders of all species at Brazos Bend eagerly consume amphibians in all stages of development. Perhaps (although it seemed unlikely) the bird considered the tadpole to be too big to swallow?

I continued to watch the Green Heron fully expecting the bird to reconsider and return to the tadpole and eat it. Instead, it caught a juvenile frog and repeated the whole process! After pecking the poor frog a few times, the Green Heron just walked off without eating it. I have only seen this sort of thing once before when a Little Blue Heron captured and then discarded a crawfish. Do these waders hunt and kill (or at least maim) instinctively without being hungry, and without lardering the prey–just like well-fed house cats? If so, stone cold killers, these fellows!

Green Heron with juvenile frog at Brazos Bend State Park, Texas — *Bad Day at Elm Lake:* this Green Heron captured, subdued, beaked, and then discarded without eating this unfortunate frog. Canon EOS 7D/500mm f/4L IS (+1.4x TC). High-speed synchronized fill-flash.

Declining Yellow-billed Cuckoos

Posted August 8, 2012 by Chris Cunningham

The eastern subspecies of the Yellow-billed Cuckoo, like many birds of North America, is in decline due in part to habitat loss. This neotropical migrant was once common to abundant during summer in appropriate environments across much of its historical range (the eastern U.S., essentially from Texas to the Canadian border) but now has stable populations only over about 2% of that range. A shy bird more often heard than seen, the Yellow-billed Cuckoo prefers forests near water with a mix of openings and thickly vegetated areas. We catch glimpses of Cuckoos from time to time, but getting a clear shot of one at close range is not an everyday occurrence.

Yellow-billed Cuckoo at Pilant Slough, Brazos Bend State Park, Texs — A cooperative Yellow-billed Cuckoo at Pilant Slough, Brazos Bend State Park, Texas

New Article and Collection: Stalking the Hunters

Posted July 25, 2012 by Two Shutterbirds

Stalking the Hunters: Observing and Photographing the Predatory Water Birds of Brazos Bend State Park, Texas explores the hunting activities of waders and other birds at one of the Texas Gulf Coast’s finest birding sites.

Little Blue Heron with American Bullfrog Tadpole at Brazos Bend State Park, Texas — This Little Blue Heron has just captured an American Bullfrog tadpole. Photo taken at 40-Acre Lake.

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