Monday, July 26, 2010

Among the Grasses: Western Meadowlark

Western Meadowlark. Image by Doug Brown

The melodious notes that rang out over the shrubs and grasses of the lower Jemez Valley signaled the territory of a certain grassland obligate species, the Western Meadowlark, one of our most popular birds. Six states list the Western Meadowlark as their state bird. Their song is almost certainly familiar, among the most beautiful and complex of North American birds, although the meadowlark often remains unseen as he sings from his exposed perch on a low shrub. It is one of our most abundant and widely distributed grassland birds, inhabiting open country from natural and planted grasslands of the Northern Great Plains to tidal flats along the Pacific Ocean, and from sea level to mountain meadows.

When viewed from the back, his and her colors are cryptic, designed to blend in with their desert, grassland or shrubland backdrop. But, when viewed from the front, this gifted songster can be easily recognized by the bright yellow breast with the V-shaped black bib. Despite the fact that its appearance is distinctively yellow and brown, it is most closely related to the blackbird family that includes Red-winged Blackbird, grackles, and orioles. It also is closely related to the Eastern Meadowlark, remarkably similar in appearance but with a very different song, equally captivating despite its more simple tune.

It would seem logical that two species that diverged at some point in their evolution due to differing habitats, would evolve different feather coloration, but they are nearly impossible to tell apart. Over time, their respective songs have changed greatly. It is by listening that one most oven can tell them apart. Today, both meadowlarks can be found in New Mexico, sometimes in overlapping areas. So, they look alike but sing a different tune. Might one be attracted to the other? Studies have shown that the two species hybridize only very rarely, and then only at the edge of the range where few mates are available. Captive breeding experiments found that hybrid meadowlarks were fertile, but produced few eggs that hatched. Obviously, their sense of self, as well as nature, protects the species from becoming hopelessly intermingled.

The nest of the Western Meadowlark usually is partially covered by a grass roof, but nests vary from completely open to a complete roof and an entrance tunnel several feet long. When Western and Eastern Meadowlarks nest in the same area, the Western Meadowlark male will defend his territory against all male meadowlarks of either species. He usually has two mates at the same time and they do all the incubation and brooding, and most of the feeding of the young.
Although the overall population of Western Meadowlark continues to remain high, long-term studies have shown an ongoing decline (1966-2006). For meadowlarks that nest in cultivated fields, haying, or tilling to control weeds, destroys all young unable to fly and a high number of incubating females. Conversion of cultivated fields to planted grassland benefits the species, but may not be possible given the demands of our ever-expanding population. Delaying the use of heavy equipment until young have fledged would certainly improve nest success. This; however, is unlikely to be a factor in the largely uncultivated region of western New Mexico. Grazing appears to have little impact on populations of Western Meadowlark.

Like many species of birds, solid information about the decline in populations of the meadowlark is lacking and more research is needed. Like a juggler with too many objects afloat, there are simply not enough financial resources to study every animal to the fullest extent possible to determine the best management practices for that species. The threats that challenge meadowlark populations are common to, not only the many grassland birds in decline, but other wildlife of the Great Plains grasslands. Finding a solution will not be easy among the many interests that compete for precious land use. Most often, when humans and wildlife compete, it is the animals that suffer. Let’s hope that the crystal clear notes in the hauntingly melodious song of the meadowlark does not become only a distant memory, a story to be told to our great grandchildren.

Sunday, July 11, 2010

Tale of Two Families

Western Kingbird. Photo by David Powell

Watching ‘my’ backyards birds is something less than an obsession, but still an important part of each day. I’ve envied friends who have been able to attract Barn Swallows to nest under their porches. A brilliantly colored swallow once visited my Rio Rancho porch in the spring but, obviously, found it lacking. I put up a nest platform on the side of my house hoping for a roadrunner to no avail. Three nest boxes hang from trees in my yard in hopes of attracting a flycatcher, chickadee or another cavity nesting species, but none of those has decided to call my yard home. Only the lowly House Sparrow has taken advantage of my generosity, building messy nests and defending them from all others.

So, it was with great joy that I discovered a Western Kingbird that had taken up residence in the dying ash tree in the front yard three years ago. That first year, while the tree still held a bounty of dark green leaves, it wasn’t until four lemon yellow fluffballs were noisily perched atop a high branch begging for insect meals delivered by their harried parents that I discovered the nest. They returned again the following year, possibly not the same adults, but choosing the same tree and successfully rearing three fledged young.

This year, I was waiting for them, listening for the bubbly that would announce their return from parts south. Arriving right on schedule, I was able to watch the nest building process as the tree yielded better views. Each year there are fewer leaves as the tree dies slowly due to an earlier infestation of ash borers. Fluffy best describes the messy cup built with grasses, twigs, and what appears to be cotton. I would watch one parent stand guard atop the highest branch, chipping, sallying forth to collect insects and deliver them into the tree. I expected young ones to emerge any day and checked the nest from a distance several times each day. Although I couldn’t see anything in the nest, the presence of vigilant parents indicated the presence of life in the nest.

Adult Cooper's Hawk. Photo by David Powell

Four years ago, a large stick nest appeared in one of the majestic cottonwoods in the park near my home. It held a pair of Cooper’s Hawks that successfully raised two young that year. It became part of my regular walk just so I could check on its progress, watching the young grow and eventually fledge. When the young ones showed up in my back yard, fumbling as they tested their hunting skills, I thrilled to the real life nature show although the teenaged birds never actually caught anything. The parents; however, with stealth hunting prowess, wreaked havoc on the birds that came to feed at Restaurant Garber. The second year, the Cooper’s Hawks lost their nest to the ferocious spring winds. I found it on the ground along with broken eggshells. Last year, three babies grew up in that tree.

The dogs love our evening walk in the park, but don’t seem to understand why it is that we must rest on the bench of the picnic table where they must sit and be quiet. Three young hawks have been growing fast. Only the youngest chick still sits in the nest and it should be out any day. Others watch the nest too and there is often a small crowd with raised binoculars, all of whom worry about the fate of this family. We have become casual friends that swap stories, bonded by a certain cottonwood that holds precious cargo.

As we rounded the corner two nights ago on our way home, an adult Cooper’s Hawk sailed low across the street in front of me, only two houses north of my home. It was close enough for me to see the limp body of a bird clutched in its talons that was undoubtedly dinner for its chicks. It was; however the bubbling call of a mobbing parent that really got my attention, a frantic Western Kingbird unable to defend its young from a feathered predator – MY kingbird. It’s quiet now in the old ash tree. The kingbird parents bubble occasionally but haven’t delivered insects to the nest, at least none that I have observed now that nest watching has become ever more of an obsession.

At the large nest in the cottonwood, three other babies will live, at least for a while longer. For raptors as for the kingbirds, mortality is high. Only 1 in 4 will survive to adulthood, victims of poorly learned hunting skills, too much confidence in humans, collisions with vehicles or windows, or other accidents.

One of the most common calls we receive at Hawks Aloft is from someone who wants to have a predatory Cooper’s Hawk or Great Horned Owl removed from their property because the bird is preying on ‘their’ backyard birds. It doesn’t work that way in nature. When we create an ideal environment and stock it with food daily we attract not only the animals we desire, but those that feed higher on the food chain. If a predator is removed from this environment, one of two things will happen: there will be a population explosion that might lead to disease, or another predator will claim the territory as its own.

At my house, after two days of intensive kingbird watching, it was with sadness that I had given up on this year’s nest. This article was written and ready to send off. When I went out to move the garden hose a few minutes ago, there she was, a bright yellow female pumping insects into the still invisible chicks in the nest! All along, I had been watching the wrong nest! The active nest was snuggled into the very center of the tree in an area still vibrant with vegetation. I wonder if anything will get done in the coming days as I wait for nature to unfold.