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May 2013

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Unexpected Guests

Delighting birders, rare ‘star’ vagrants travel through Texas each year.

By Noreen Damude

If expecting to see, say, a roseate spoonbill, look again. It just might be a greater flamingo. Or, when all excited to see a wood stork, take a second look — danged if it isn’t a jabiru! When hoping to find a few scoters along the coast this spring, keep a sharp eye out; you may turn up a king eider. A bare-throated tiger-heron — that’s not like any heron I’ve ever seen in Texas before.

Is that a whimbrel? No, wait a minute. Could it be an Eskimo curlew? I thought that bird was extinct!

Imagine seeing a snowy owl, white ghost of the Arctic, or a stygian owl, mysterious denizen of the New World tropics. There could be a yellow-billed loon or a northern jaçana, a black-tailed godwit at the refuge in Brazoria or a double-toothed kite at High Island.

Where do they all come from, how and why do they occur so far from their normal ranges, and what species will be next? Avid birders are always keen to predict what the next “star” vagrant will be to visit our state.

Birder John Arvin says he has given up playing that game.

“The experience of the past several decades has shown me that while some species follow expectations, some of the recent additions totally defy explanation,” he points out.

Why does Texas boast so many birds, and why do so many unlikely species turn up? Put simply, Texas is prime avian real estate with its tremendous size and, of course, its location, location, location.

A birder’s paradise, Texas is located at ground zero for birds. North, south, east and west converge to ensure a rich cornucopia of avian surprises. Size is important, as is a long coastline and a diversity of habitats — piney woods, arid thorn-scrub, long- and short-grass prairies, mountains, valleys, rivers and lakes. There is something for nearly every bird’s taste, and lots of it. Not only that, Texas lies under the Central Flyway, strategically placed to draw in a plethora of migrants in both spring and fall.

Snowy owl

Snowy owl.

Vagrants vs. rare birds

What is vagrancy and how does it happen? A bird is considered a vagrant if it strays far from its expected breeding, wintering or migrating range. It may come from as far away as another continent, or it may reside year-round only a few hundred miles south of the border. Vagrants may or may not be rare, but they can show up far outside their normal range. Occurring anywhere at any time, most are seen during winter or migration, when birds traditionally desert their breeding grounds in search of food.

A rare bird, on the other hand, is one that is hard to observe even where it naturally occurs. Examples may include narrow endemics, endangered species or birds on the brink of extinction. Eskimo curlew still fits this last category, we hope, and has not gone over the edge.

Finally, some birds just seem rare because cryptic plumage, secretive behavior or nocturnal habits make them hard to find. The stygian owl fills this conceptual niche. Even in Latin America, these elusive owls commonly go unseen.

How birds get ‘lost’

Why some birds go astray is one of the more puzzling conundrums of avian biology. A number of factors may conspire, either singly or in concert, to cause an individual to lose its way and end up where it’s never been seen before.

Juvenile birds making their first migration without the guidance of adults occasionally overshoot or undershoot their destination. Certain species, such as wood storks and jabirus, may disperse in every direction after fledging.

Other species just seem to wander more than others. Perennial vagabonds turn up far from their traditional haunts on a surprisingly regular basis. One such inveterate gypsy is the fork-tailed flycatcher, a migrant from South America that has occurred in Texas at least 23 times — most recently last December for the Austin Christmas Bird Count. Less spectacularly in terms of distance, the varied thrush of the Pacific Northwest has turned up 42 times in Texas and as far east as Atlantic Canada.

Blue mockingbird

Blue mockingbird.

The vicissitudes of migration

Twice a year great rivers of birds flow between northern and southern latitudes, spurred by the ever-changing seasons due to the tilt of the earth. Birds migrate twice a year to take advantage of optimal conditions for survival. The vicissitudes of long-distance travel, sometimes over oceans, present both untold hazards and ample opportunities for migrants. Whether by epic or seasonal journeys or periodic disruptions caused by food shortage, birds are ultimately spurred to seek new areas to exploit as current conditions dictate.

Weather vs. climate

Birds are both helped and harmed by the effects of the weather, which brings about day-to-day changes to their world. Migratory birds are cued by shifts in wind direction and by cold or warm air masses that alert them to optimal times for departure. Unusually powerful winds or storms during migration can be devastating, killing birds by the thousands or forcing them far from their regular course. Exhausted birds, at the end of their tethers, drop down wherever they find land to rest and recover or fall into the sea to perish. Hurricanes may even waft seabirds far from their normal paths. High winds can carry oceanic birds, like the red-billed tropicbird, far north of their tropical oceanic homes.

Climate, by contrast, works over time by influencing the distribution of birds around the globe and the seasonal cycles of their lives. Severe winters create havoc by inflicting paralyzing cold, sleet or wet snow, forcing huge numbers of long­spurs and snow buntings to flee starvation on their wintering grounds.

Unseasonably hot, dry summers result in food scarcity over large areas by drying up fields, woodlands, lakes, marshes and rivers, ravaging local bird populations and forcing them to move away. Long-term heat waves and persistent drought may force a few permanent residents of north-central Mexico to cross the border into Texas in search of better habitat conditions. Elegant trogon, blue mockingbird and masked tityra are among the avian delights that have found temporary refuge in South Texas, causing a whirlwind of excitement in the birding world.

Contingent movers and shakers

Unlike most migratory songbirds that have traditional wintering ranges, irruptive species do not. Irruptive species move in response to changes in food supplies. Their movements tend to be subtle, like those of the pinyon jay. After nesting is complete, the jays wander the landscape looking for pockets of food, most notably when pinyon seed crops crash. Of course, some irruptions can be spectacular, bringing in huge flocks of evening grosbeaks, red crossbills, pine siskins or redpolls from the north.

Many irruptive species depend heavily on specialized diets of conifer seeds as their mainstay. Given plenty of food, they are quite capable of surviving both cold and snow. The snowy owl, also an irruptive species, feeds predominantly on lemmings, rodents whose immense populations crash at regular intervals. Every 10 years or so these spectacular diurnal raptors are forced to flee their traditional Arctic wintering grounds in search of alternate food, occasionally coming as far south as Texas.

Elegant trogon

Elegant trogon.

Other unexpected birds

Other potential surprising birds may be escapees from zoos or private collections. Pets accidentally or intentionally released from cages contribute to many an unanticipated rare bird sighting. Budgies or Afro-Asian mannikin finches fit this paradigm.

Hitchhikers include birds that did not get here under their own steam, landing on boats far at sea due to exhaustion or transported intentionally and released in Texas. Understandably, they don’t qualify as countable species in the “New to Texas” list.

Finally, some migratory birds may suffer physical or genetic impairments that affect their navigational systems, sending them off in the wrong direction. Usually these waifs don’t survive long enough to be counted anywhere.

Planning and documentation

Surprise visitors cause great frissons of excitement among novice and hard-core birders alike. Birders, wayfarers in their own right, will travel almost as far, sometimes farther, than birds to add a new species to their life lists. When planning a trip to the field, whether on a quest or a lark, keep in mind the importance of documentation. Take photographs, including habitat shots, or make sketches, indicating salient field marks. Make sure to describe the bird’s behavior: how it flies, how high or low, how does it move along the ground, does it walk or hop, how and where does it feed and on what. If you have a camcorder, all the better. Even if you are not sure what it is, send your materials in to the Texas Bird Records Committee (texasbirds.org/tbrc) for validation.

You may not be so lucky as to cop a new bird for the state, but by birding on the qui vive, alert to any unfamiliar song or call, you’ll increase your odds by orders of magnitude. Besides, enjoying all the usual suspects, glorious gems in their own right, is not to lose the game. But, should you manage to grab the brass ring and find a new bird for Texas, know that it’s a coveted prize for any birder. Not only that, you will be adding immensely to our knowledge of Texas birdlife.


My favorite surprises

The Texas Bird Records Committee currently boasts 638 documented species on its state list. The most recent addition, as of June 2012, was a double-toothed kite. The 2012 Austin Christmas Bird Count recorded a fork-tailed flycatcher, a migrant far from its South American home — not new to Texas, but thrillingly unexpected nonetheless.

Here are a few of my favorite pairs of “surprise visitors.” Some I have seen, others I long to see, and the last I pray still abides: a harlequin duck and a masked duck; a red phalarope and a red-billed tropicbird; a snowy owl and a stygian owl; a northern wheatear and a fork-tailed flycatcher; an elegant trogon and a varied thrush; a pinyon jay and a blue mockingbird. And one perhaps (or perhaps not) extinct Eskimo curlew.


Related stories

2013 Spring/Summer Birding Calendar

Highways in the Sky: Migration Strategies

For more on bird-watching, see our Birding page

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