The White Choir: Light Geese

Waterfowl at dawn - Bosque Del Apache National Wildlife Refuge. All images in this post by David Powell.

“In complete darkness long before sunrise, you know that you are surrounded. The sound of the white choir crescendos, rising in intensity and volume until it floods your senses. As night gives way to day, the sensation transforms from audio to visual.” John Vradenburg, supervisory biologist at Bosque del Apache National Wildlife Refuge, shared his passion for the wintering waterfowl and Sandhill Cranes that are the signature birds of the refuge.

Light Geese, as they are referred to by biologists, are actually two different goose species, Snow Goose and Ross’ Goose. The Snow Goose is a medium-sized goose with a distinctive blackish “grinning patch” or “smile”, while the Ross’ Goose is smaller and lacks the grin patch. Most adults of both species are completely white except for some gray under the wings and black wingtips.

Light geese breed colonially in subarctic and arctic tundra near the coast on featureless terrain near ponds, shallow lakes, streams, or islands in braided deltas. Some high arctic colonies are located well inland on rolling terrain, exposed slopes of ravines, and cliff edges, but most nest in low-lying wet meadows with plenty of sedges and grasses. The preferred nesting areas are clear of snow early in the season and not flooded during spring thaw.

Bosque del Apache NWR hosts about 45,000 of the two goose species each winter. They begin showing up in mid-October and stay until mid-March. The population peaks in late November through early December when migrants that will settle further south at wetlands in Mexico, stop here to rest and refuel. In the Middle Rio Grande Valley, populations appear stable, although numbers of light geese nationwide are millions beyond carrying capacity, according to Vradenburg. Overpopulation makes the birds susceptible to disease on wintering grounds and increases competition for nest sites and food resources on the Arctic tundra.

Parents stay with their young throughout the first winter. Families travel together on both the southbound and northbound migrations, separating only after they return to the arctic breeding grounds. Family groups can easily be seen in migrating and wintering flocks and, amazingly, manage to remain together even when landing in the midst of a densely packed raft of floating geese at roost sites.

Light goose hunting was banned in parts of the United States in 1916 due to low population levels. Hunting was allowed again in 1975 after the population had significantly increased. Today, hunting mortality, despite liberal bag limits, has so far failed to curb the 5% annual growth of most populations. Some populations have grown so large that the geese are destroying their nesting habitat.

Light Geese did not always winter in the Middle Rio Grande Valley, but began showing up in the 1960s and 1970s. Vradenburg thinks the geese always flew over the valley but wintered in the highlands and central valley of Mexico, and along the Gulf coast. As more managed wetlands and reservoirs in Colorado created desirable roosting and foraging habitat, the population shifted. Bosque del Apache happened to be in the right spot for the geese and other birds to stop over.

There is a blue morph of both species also occurs in about 10% of the population. The dark color of the blue morph is controlled by a single gene, with dark being partially dominant over white. If a pure dark goose mates with a white goose, the offspring will all be dark, except for a possible white belly. If two white geese mate, they have only white offspring. If two dark geese mate, they will have mostly dark offspring, but might have a few white ones too.

Bosque del Apache was established in 1939, for the purpose of providing habitat for migratory and breeding water birds. Before it became a wildlife refuge, it was mesic (wet) floodplain habitat with farmland and upland areas. Then, more natural conditions existed since the river had not yet been controlled. The refuge was developed when the levee was moved to control annual spring flooding and confine the Rio Grande. After the low flow channel was created, the refuge had to install and intensively manage the wetlands we see there today.

“Heard long before they are seen, they let us know that that the migration season is upon us."

The Bosque and the Snow Geese, in particular, are a multi-sensational experience that combines the mass of thousands of geese, audio and visual, where you can literally lose your voice to the cacophony of mass of white flight,” reports the enthusiastic Vradenburg of the experience of visiting one of the premier wildlife refuges in the United States.

At only $5/car, it makes for an impressive and entertaining winter day trip, only 120 miles south of Jemez Springs. If you go, plan to depart late morning, stopping at one of the local eateries for lunch, and arriving at the refuge in early afternoon. Be sure to stay for evening fly-in when the geese, cranes and ducks return to their roost sites for the night. You’ll be glad you stayed to hear the night choir.

A Family Affair: American Avocet

American Avocet. Photo by David Powell

The two American Avocets stood, silent but alert, in the shallows of a New Mexico wetland. Brilliant slivers of crimson in the eastern sky heralded the onset of the day. The female had been assiduous in her companionship, and eventually the male accepted her presence. Now, the two were rarely far from one another. Like a pair of ballet dancers, the birds were the epitome of elegance with their striking feathers and graceful, upturned bills, the silhouette of their image reflected in the mirror of the glassy surface of the water.

The dance began when the female slowly and deliberately leaned forward, stretching her neck as far as possible, submerging her bill into the water. This was the cue for the male to begin his solo performance. He began to preen his feathers on the side nearest his mate, dipping his bill into the water and lifting it to his breast. With the second dip, he shook his bill splashing water on the pair. He continued, moving in an ever increasing frenzy of vigorous splashing, until he joined the still motionless female, and they became one. After, in the grande finale of their ritualized dance, the pair stood side by side with necks intertwined, and ran as one through the shallows.

Avocets prefer to nest on islands within a wetland, if possible, because it provides some protection from predators. Their nest-search, which also is part of the pair formation, includes ritualized scraping displays. The final nest site often is somewhat elevated with a clear view from which the pair can scan for predators. Sometimes, females lay eggs in the nest of another female, who then incubates the eggs. Avocet eggs have been found in the nests of other species too, such as gulls. Likewise, eggs of other species sometimes are found in avocet nests. So, an avocet parent might raise a mixed species family that could include Black-necked Stilts or even terns.

Modern day parenting is the norm, where both parents take turns incubating the average size clutch of four eggs. Early on, the male performs on the bulk of incubation. In warmer areas, with relentless sun baking the sandy shores, incubation consists of cooling, rather than warming, the eggs. Parents soak their belly feathers before sitting on the nest. Evaporative cooling prevents the eggs from getting too warm.

For a vulnerable chick, life on the edge of a wetland is precarious. Young are up and out of the nest within 24 hours. Day old chicks can already walk, swim, and dive. Older, but still flightless, chicks can dive and swim up to 21 feet underwater using their wings and feet. If the nest is on an island, chicks follow their parents and swim to the shore, where they are raised in a nursery area with shallow water and dense vegetation for cover. Often, several avocet pairs will cooperatively raise their young in a communal nursery. Here, the chicks might a brooded by different parents.

Often, female parents abandon the nursery before the young a fully independent, leaving the remainder of the care with the males. Maybe, just maybe this is part of the reason why he is reluctant to initiate courtship, knowing what his parenting duties will be, and why avocets rarely have the same mate the following season.

The Bird that Walks on Water - Clark's and Western Grebe

Clark's Grebe. Photo by David Powell

Perhaps running on water might be a more appropriate term for part of the captivating courtship ritual of these two closely related, fascinating species. Not considered ducks, geese, or even waterfowl, these less commonly observed birds are considered just “waterbirds”, a somewhat ignominious term given their spectacular breeding season displays considered to be among the most complex known in birds. Those of you lucky enough to have witnessed the event will likely always remember it. Certainly, it is frequently shown on television nature shows. After a series of calls and posturing, the pair rises up on their feet, and with wings beating furiously, literally run across the surface of the water. A second ritual, “the weed ceremony” cements the pair bond. Beginning like the prior example, a weed dancing couple simultaneously dive to the lake bottom to gather a mouthful of vegetation, rise to the surface, and then rise on the their feet while holding the vegetation bill-to-bill.

Clark’s and Western Grebes are remarkably similar in appearance, with only subtle differences in facial pattern, bill color, and calls to differentiate the birds to our human eye. In fact, the two are so similar that from 1886 to 1985 they were considered to be one species. Highly social, they can be found on our larger lakes, particularly those with the marshy vegetation necessary for nesting during the spring. During winter, on open water, they may be found in large rafts of both species, where they hunt mainly for small fish and other aquatic animals, which are usually swallowed underwater, a seemingly impossible, if not illogical feat. Furthermore, each individual can consume up to a pound of fish a day, so large groups are capable of quickly depleting the food resources in a small pond or lake.

Superbly designed to efficiently ‘fly’ underwater, grebes have short wings and feet and legs that are positioned near the rear of their bodies, making them ungainly on land. In fact, most grebes rarely set foot on terra firma, except during the nesting process. Grebes almost never fly except during migration which occurs at night. Additionally, grebes, replace most of their feathers all at one time, rendering them flightless for much of their nesting period. This effectively restricts their range to the pond or lake that they selected for their nest site, and subjects the pair and their young to the perils of uncertain weather, water levels, and adequate food supplies.

Nestling grebes are able to swim and dive within 24 hours of birth, but are not terribly water-proof. Like loons, a closely related species, young grebes spend most of their early weeks riding on the backs of their parents. At this time of year, young grebes are independent of their parents and might be found in close company with others of their kind. Check out the lakes of New Mexico for a look are these rare and interesting birds! If you’re lucky you might even see the dance!