New Mexico Birds

A Bear of a Year

2011-10-26T19:22:00.002-06:00

Emaciated bear cub at The Wildilfe Center, Espanola, NM

A neighbor’s compost pile dug up and trashed. Dogs barking during the night. Hummingbird feeders ripped from their hangers. Bird baths overturned. The perpetrator of the vandalism left ample evidence of his or her presence, beginning in late September. It has been several years since a black bear made itself evident in Area 3 north of Jemez Springs, not since the infamous shooting of a harmless bear by a local resident. He paraded the carcass to friends in Belen, was busted by New Mexico Department of Game and Fish when he attempted to have the animal mounted, was roundly roasted in the Thunder, and moved out of state shortly thereafter.

Although, my area of expertise is all things avian, not mammalian, it seems most appropriate to consider the plight of these omnivores during our driest year on record. I contacted Katherine Eagleson, Director of The Wildlife Center (TWC) in Espanola, New Mexico’s largest wildlife rehabilitation center and the only resource for injured, orphaned, or starving large mammals, including predatory mammals. The center has taken in 46 black bears since January 1, 2011. As of October 17, they had 33 bears on site; normal is 6-8 bears.

Wildlife Center staff working performing triage on a new arrival

According to Eagleson, drought has the greatest effect on bears as well as other wildlife. Most of a bear’s diet consists of vegetation. Soft mass (mast) includes berries, grasses and other vegetation and hard mast includes nuts, such as pinyon, and most importantly, acorns, of which there are few this year. It was so dry throughout the winter that, in the early part of this year and through early summer, even the grasses were failing in bears’ foraging areas. Females and their cubs emerged from their dens when little food was available. Females won’t abandon cubs due to food shortage, but the cubs follow their mothers and may be predated upon by other bears. Underweight youngsters are more vulnerable to predation and their biggest threat is other bears. Coyotes and mountain lions also prey upon young bears.

Then, the fires arrived, exacerbating an already tenuous existence and forcing bears from known habitat into the territories of other animals. Starving bears descended on communities statewide, looking for food. According to Eagleson, there has been no formal assessment of food sources for bears, something she would like to see developed as a citizen science project. New Mexico Department of Game and Fish (NMGF) officers have killed over 200 bears this year, problem bears that broke into cabins, have been hit by cars or have other injuries, or have lost their fear of humans. Humans do a lot to exacerbate the problem of habituated bears by leaving out garbage, bird feeders, and feeding dogs outdoors. “A fed bear is a dead bear.”

Young bear in one of the bruin holding pens at The Wildlife Center

TWC only keeps first and second year bears. Other bears, unless injured, are returned to forested areas throughout the state. Cubs normally stay with their mothers for 16-18 months before dispersing. Some female cubs even establish territories adjacent to their mothers. Young born in 2010 and 2011 would normally still be with their mothers and are not ready to be on their own.

Second year bears, those born in 2010, are fattened up as much as possible and are now being released in areas where it is hoped that they will begin hibernation soon. One such bear is the one that was found in Albuquerque near Coors Blvd. The emaciated 18 month old cub arrived at TWC weighing only 50 pounds. During its stint in captivity, it packed on another 150 pounds and became a very feisty bear that needed to be released NOW. All bears are anesthetized for release. Their release is carefully coordinated with NMGF biologists, who select sites that have low human impacts, little traffic, and that should have a food source in the spring when the bear emerges from hibernation. Release sites also have to be evaluated for carrying capacity and the number of bears already present in the area.

Cubs born in 2011 will have to remain on site throughout this winter, and will be released in the spring of 2012. Although they will be very young to be independent, only be 15 months old, TWC can’t effectively keep them over the next summer without seriously habituating them to humans.

Housing and feeding 33 bears might be considered overwhelming to some, but TWC staff seem to take it all in stride. Each bear consumes 6 - 7 pounds of dog food a day, totaling 200 pounds each and every day. That doesn’t include the apples, melons and other fruit donated by grocery stores and individuals. In New Mexico, healthy females weigh 130 – 180 pounds while males tip the scales at 250 – 300 pounds. Bears need to gain 30% of their weight before they got into hibernation. Breeding for bears occurs in June, but fertilization is delayed. If the female is underweight, the egg will not attach and no young will be born the following winter. Eagleson anticipates fairly low cub production in the spring of 2012.

Bears at TWC are held at an off-site location, and the influx of 2011 has required the construction of additional enclosures to safely house their expanded bruin population. When I wondered how one goes about cleaning an enclosure that contains large wild bears, Eagleson quickly responded, “Cleaning through intimidation! We use the same people all of the time. They go in and bang on the doors and yell at the bear and so on.” TWC did receive $20,000 in donated dog food, but needs cash donations to help pay for new enclosures and also pay trained staff to clean the enclosures and care for bears.

It’s an admirable job, and one that I am glad doesn’t belong to me. TWC is always looking for new volunteers. They hold periodic training classes throughout the year. But mostly, they could use cash donations! You can donate online www.thewildlifecenter.org. Please contact TWC center for more information if you are interested in becoming a TWC volunteer.

Forest Hawk

2011-09-25T17:13:00.002-06:00

Juvenile Cooper's Hawk. Image by David Powell.

Just two days ago, two juvenile birds joined our avian ambassador team, a young Common Raven and a male Cooper’s Hawk (more about the raven in a later issue), courtesy of the Wildlife Center in Espanola, New Mexico. Both had wing injuries that rendered them non-flighted and permanently non-releasable. The good folks at the center had toiled long and hard to rehabilitate the two so they could be returned to the wild, but unless a bird is nearly 100% fit, it would not survive. In cases like these, the only choices are to place them with an educational organization like Hawks Aloft or toeuthanize them.

Coops, as we affectionately call them, are notoriously challenging to handle in captivity and have a well-deserved reputation for aggression. They belong to the Accipiter family, forest hawks that have short, rounded wings and long tails to help them maneuver through dense vegetation in search of prey, primarily other birds. The other two species of Accipiter in North America are the tiny, Sharp-shinned Hawk and the Northern Goshawk. Both of these species nest in coniferous forest where they can coexist because the size of their prey it significantly different.

Adult Cooper's Hawk. Image by David Powell.

This little fellow, who still wears the bright yellow eyes of a youngster, arrived thrashing around in a pet carrier, acting every bit like he could take me on and win. Patience and extreme calm are essential when training a bird that arrives from the wild, helping the education bird adjust to life in captivity, and ultimately being presented at public education programs.

You might wisely ask why we would want such a volatile species for our education program. Our most common urban nesting raptor -- the Cooper's Hawk – is reknowned for its aggressive nest defense behavior. Each year, during the month of June, we field numerous phone calls about aggressive hawks. During the courtship, egg-laying, and incubation stages the birds are unobtrusive and, in fact, are very difficult to detect.

We attached jesses almost immediately after he arrived, figuring that it already was a stressful day, and it might be better to get on with the final indignity of attaching the leather straps that would tether him throughout his training and also later during public programs. Then, we let him rest for a full 24 hours before bothering him again.

Adult Cooper's Hawk with prey. Image by David Powell.

All this changes; however, once the young have hatched, and the parents have a greater investment in this year's nest. They can become extremely defensive, and the unwary human who inadvertently crosses into their territory first hears the loud, scolding call, "Kek, Kek, Kek, KEk, KEk, KEK, KEK, KEK!" Then, when they turn to see the source of the insistent warning, they find themselves face-to-feather with a furious, rufous-breasted, gray-backed bullet with blood red eyes. The automatic response for most humans is to fall to the ground, cringing in terror, lest the bird actually strike them. Then, after escaping from the incident unharmed, they scramble to the telephone and begin calling anyone who might help with the situation. Enter the Hawks Aloft education program for homeowners.

This morning, when I lifted the cloth that covered the carrier, he looked ready for battle, all 2/3 pound of him. He flipped over on his back and presented his talons, ready to grab me. A quick flip of the towel and I had him in my hands, attaching the lead. We sat together in the sunny living room as I tried nonverbally to communicate that this really would be okay, that I would never hurt him.

Adult Cooper's Hawk. Image by David Powell.

Most of the callers appreciate 'their' hawks, and just need a little education and assistance to avoid arousing the defense mechanism of the feisty parent, doing their best to protect their young nestlings from the perceived human danger. It helps when we give them tips to avoid arousing the angst of the hawk, and reassure them that Cooper’s Hawk will only rarely actually strike a human. Generally, they pull up at the last minute. Biologically, it would not be wise for a bird weighing between ½ and 1 pound to take on a 100+ pound human. There have been no reports published of serious human damage incurred from the attack of a Cooper’s Hawk. We work with them through the 3-4 week period, and the result is usually a happy home or business owner once the young are out of the nest, and the aggression stops as suddenly as it began.

Now, several hours later, he is quietly sitting on a specially made perch atop a covered table in the shrouded extra room (Coops can eject their waste stream with considerable force over great distances). A de-feathered quail carcass sits by beside him, hopefully tempting him to dine. I only pause at the door to check on his well-being. It is enough for today and tomorrow, until this becomes normal to him. Only then will we move on to the next part of training. We have all the time in the world.

Then, as the young begin to disperse with their newly earned fledgling independence, the phone begins to ring again, with a call arriving almost every day. The young birds, in their early hunting attempts, chase anything feathered, often pigeons or sparrows. The juvenile Coop pursues them with great abandon right into the warehouse, building, or batting cage and, once inside, cannot figure out how to get back out. We have become adept at catching and releasing them. It makes for a busy summer.

One day, possibly months from now, he will make his debut, educating the public about an often misunderstood raptor, the Cooper’s Hawk. While all of our education birds do have names that we use to distinguish them from one another, they do not respond to being called by name. We rarely use their names in presentations. Only when the name is educational in some way, relative to the species, the injury, or the location where the bird was found, is it ever revealed. This little guy will have just such an educational name. We call him Forest – Forest Hawk.

Tiny Titans: Hummingbirds

2011-08-25T14:17:00.003-06:00

Juvenile and female hummingbirds can have remarkably similar plumage, making identification very difficult. Image by Keith Bauer.

There’s something mesmerizing about watching them buzz around a feeder, a seemingly endless line of thirsty beaks. Have you ever tried to count how many hummingbirds actually visit your feeders at one time? Some folks I know maintain 10 or more feeders, going through 50 pounds of sugar a week! A friend stopped by today to drop off one of his fabulous hummie images and professed to know, not the total number that visit his feeder, but the number Rufous Hummingbirds present at his feeders. Two! There’s only room for one little red devil at each feeder – they drive off all others. We all watch them; and many of us feed them. These tiny titans are found only in the Western Hemisphere. They might look tiny and fragile, but hummies are anything but. They pack some amazing adaptations suited to their diminutive lifestyle.

They weigh in between 2 and 20 grams, depending on the species, about three cents worth, or the weight of 3 U.S. penny coins at 3 grams each. The world’s smallest living bird is the Bee Hummingbird, native to Cuba, at 1.8 grams (0.063 oz) and 2 inches in length. Our most common nesting hummingbird is the Black-chinned that weighs 9 grams. The slightly larger Broad-tailed Hummingbirds dominate at higher elevations. And, Rufous and Calliope Hummingbirds arrive in July on their way south. For me, the Fourth of July weekend, is filled with anticipation as I wait and watch my Jemez mountain feeders for the little red hummer that always seems to appear just then.

Hummingbirds can fly vertically in order to capture fluid in pendulant flowers, like this juvenile Rufous Hummingbird. Image by David Powell.

Hummingbirds got their name because their wings beat so fast that they make a humming sound, similar to that of a bee’s buzz. They can fly forward, backward, rise vertically, and hover. In order to understand how this type of flight is possible, consider that their wings move in a figure 8 motion with about 50-80 wing beats per second. At the same time their tiny heart races too, ranging from 250 beats per minute while at rest to 1,250 beats per minute in flight. Hummingbirds can reach speeds of up to 60 miles per hour.

With such a high octane lifestyle, hummingbirds require disproportionate quantities of nectar or sugar water to fuel their high-energy life style, as much as 90% of their diet. Their elevated metabolism requires an enormous food intake, typically more than one and one-half times the bird's weight in nectar alone each day. Flowers provide their food naturally, but when temperatures plummet, these sources dry up or disappear. Then, artificial sugar water feeders become critically important to survival.

The diminutive Calliope Hummingbird is the smallest North American species. Image by David Powell.

Hummers eat small insects, spiders, ants, and caterpillars, and even poach trapped insects from spider webs. When you see them hovering in mid-air or zipping to and from a perch they are almost certainly picking off flying insects. Although, high-calorie nectar or sugar water is the dominant part of their diet, protein-rich insects are also important, which also is affected by unexpected temperature drops.

Some hummingbirds are quite confiding when around humans, seemingly oblivious to our presence. Image by David Powell.

Most North American hummingbirds avoid cold weather extremes by migrating to Mexico or further south. However, many hummingbirds, remain year-round in the southern U.S. , in places like California and Arizona. Increasingly, some hummingbirds that typically migrate to Mexico, such as Rufous Hummingbirds, are wintering in the southeastern U.S. , trading a southerly migration for an eastward journey. Parts of the southeast are seeing increasingly large populations of our western species during the winter months.

They migrate in response to hormonal changes, which are triggered by decreasing daylight hours. Nothing you can do will make them stay too long, so it's not necessary to stop feeding them to force them to go south. On the contrary, they need to fatten up to nearly double normal body weight to survive the journey, and appreciate your feeder more than ever up until literally the last minute before they depart. The standard recommendation now is to keep feeders in place and until two weeks after the last hummingbird sighting.

The Black-chinned Hummingbird is the most common nesting bird in the Middle Rio Grande Bosque. Image by David Powell.

When late-departing migrants are surprised by cold weather, or when abnormal freezes affect resident hummingbirds, intervention by well intentioned people with back yard feeders can be life-saving. Hummingbirds survive the night by ingesting copious amounts of nectar at dusk, storing this reserve in their crops and digesting it throughout the night, during sleep. In cold conditions, hummingbirds drop into a hibernation-like state (torpor) which conserves energy through reduced heart rate, breathing and temperature, but which also increases the birds' risk to predation. You can help hummingbirds during these extremes by providing plenty of sugar water, and by insuring that the syrup remains unfrozen.

Sugar water in feeders will remain liquid at 32 degrees Fahrenheit, the temperature where plain water freezes, but if temperatures drop much below this level, even sugar water will freeze. Higher concentrations of sugar to water lower the freezing point, but become difficult for hummingbirds to ingest, and are not recommended. Monitor your feeders closely. If temperatures are forecast to fall below freezing overnight, bring your feeders indoors after dark, after birds have quit feeding, and then re-hang them at the earliest light, before hummingbirds begin feeding.

Increasing numbers of Rufous Hummingbirds and other species now are wintering in the southeastern U.S. in an easterly rather than southerly migration. Might that be fueled by the presence of feeders? Image by David Powell.

In early February 2011, much of the U.S. was hit by arctic air. In southeastern Arizona, where Costa's and Anna's Hummingbirds are common throughout the winter, early morning temperatures dropped to the mid-teens and below, impacting insects and flowers. Artificial feeders became critical to hummingbird survival, and even these would freeze solid if unattended. Fortunately, bird lovers across the area stepped up and kept feeders filled and thawed. Freezing weather is unavoidable, but when it comes, a little effort on our part will make a world of difference to our hummingbirds.

Hummingbird populations appear to be positively affected by our penchant for watching them at our feeders. Let’s give them a helping hand this fall, by keeping our feeders cleaned and filled until all have had a chance to move south.

Stand Replacement Fire and Its Effect on Birds

2011-08-25T13:51:00.006-06:00

The Mexican Spotted Owl is one species that was affected by the Las Conchas wildfire in the Jemez Mountains, NM, in 2012.

We all have watched in dismay as the Las Conchas fire has incinerated some 156,000 acres of our beloved Jemez Mountains, destroying homes and livelihoods of those unfortunate to live within the boundaries of the largest wildfire in the history of New Mexico. I’m not sure which was worse, watching the giant plume of smoke tower into what appeared to be cumulus clouds or coughing and hacking as the thick, viscous smoke settled into the canyon during the night obscuring all distance vision during the morning. Although the fire certainly traumatized many humans, no human life was lost.

What effect will this fire have on the wildlife that called the Jemez Mountains home? Deer, elk, bobcat and bear sightings have increased in communities as animals were driven from their habitat. Concern has been raised about the Jemez Mountain salamander, a candidate species for federal listing, and the Mexican Spotted Owl, a federally threatened species listed, in part, due to the threat to its populations from catastrophic wildfire.

Many species of birds found in the coniferous mountain forests of the southwest, particularly those inhabiting ponderosa pine forests, evolved in a habitat that historically experienced recurrent low to moderate severity fires about once a decade. Beginning in the last century, grazing of surface fuels by introduced livestock, clear-cut logging, and widespread fire suppression has greatly reduced the frequency of surface fires in these forests. The change in fire frequency has altered forest composition from a formerly park-like habitat with open canopy and a grassy understory to dense thickets of young trees with many downed branches. This altered environment has resulted in larger and more intense fires.

The immediate effect of fire during the spring and summer breeding season is the loss of the reproduction for most species of birds. Although parents forced to abandon their nests can escape the flames, unflighted young are hopelessly trapped. There also is additional pressure on adults that must resettle into an unfamiliar area that almost certainly is already inhabited by other animals that rely on that habitat for food, thus increasing foraging pressure for all.

Remnants of the coniferous forest after the Scott Able Fire burned 16,000 acres in the Lincoln National Forest, NM in 2000. Photo by Mike Stake.

In May 2000, the Scott Able Fire burned 16,000 acres of coniferous forest in the Lincoln National Forest, south of Cloudcroft, New Mexico, affecting 9 known nesting territories for Mexican Spotted Owl (MSOW). Portions of the forest were completely scorched leaving only standing dead trees, while other areas burned in a patchwork pattern. Hawks Aloft conducted a four-year study of the 9 known Mexican Spotted Owl territories and conducted a complete inventory of the burn and surrounding buffer zone in 2005 to document owl activity in addition to the nine known territories. During year one of our study, we detected no nesting activity for MSOW. However, each year as the vegetation underwent successional growth, owls and other birds re-occupied the canyons. Over the course of the study, we found Mexican Spotted Owls in 8 of 9 survey sites. Although owls were rarely observed in burned areas, we often found them in unburned areas adjacent to burned habitat. Based on our results, it appears that the fire shifted Spotted Owl territories, and that some owls were using burned areas for nocturnal foraging, while breeding in adjacent unburned habitat.Purple Martins utilized standing snags in the Scott Able burn area, established the highest elevation known for breeding for this species. Photo by Mike Stake.
Like many fires, the Scott Able fire burned some areas in a mosaic pattern, leaving some trees untouched while others were redoced to matchsticks. Photo by Mike Stake.
One of the Purple Martin breeding colonies in our study. Photo by Mike Stake.

We also conducted avian surveys at a series of points within the burned area and at control points that were not affected by that fire. The results of this four year study demonstrate how some avian groups responded positively to successional habitat created by fire, while other avian groups responded negatively. Most species were documented using burned habitat, and some species were found almost exclusively in burned habitat. House Wrens, Violet-green Swallows, Western Bluebirds and Green-tailed Towhees were the most commonly recorded species in burned habitat. Species using scrub vegetation, such as Green-tailed Towhee and MacGillivray’s Warbler showed a steady increase throughout the study that likely continued for many years following its completion.
MacGillivray's Warbler is one of the species that responded positively to fire over time. Photo by Doug Brown.

We also found some surprises, such as the discovery of a nesting population of Purple Martins that were utilizing the standing snags. This led to a two-year study of the martins nesting in a previously unknown region and at the highest elevation reported for the species.

Some birds, like Three-toed Woodpeckers, were associated with numerous snags, undoubtedly benefiting from an increased availability of insects or nesting cavities. Our three studies associated with the Scott Able Fire demonstrated the importance of snags, and post-fire management should consider the effects of snag removal on birds. All snags might not be of equal value to birds. Snags in close proximity to unburned habitat, rather than in isolated patches, might provide better conditions for cavity nesting species. There is much to learn by studying the effect of catastrophic fire on birds, particularly on the relative value of different snag sizes and densities to different groups of birds, especially species of conservation concern.

Although the Scott Able fire was an intense crown fire, it was still only 10% as large as the Las Conchas fire. Our studies found that many bird species either tolerated or benefited from the habitat modification. We observed most species at least once in burned habitat, and several priority and management indicator species regularly used burned habitat. We do not discount the importance of wildfire prevention, especially when human lives and property are threatened; however, our observations revealed some benefits of such a fire. Because many species use, and even depend on, burned habitat, managers should consider wildfires to be of some long-term benefit to the avian community.

For further reading, copies of all three reports are available on the Hawks Aloft website at www.hawksaloft.org, under the Conservation tab/Publications.

The White Choir: Light Geese

2011-02-20T09:45:00.004-07:00

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.

Marsh Hawk: Northern Harrier

2011-02-11T18:45:00.005-07:00

A juvenile Northern Harrier tries to defend a fish carcass from an adult female. All images in this post by Doug Brown, except the final image.

Perched atop the limp body of a dead snow goose lying among the grasses in shallow water, the slim-bodied raptor yanked out yet another tuft of white feathers. The brown feathers that characterize female and young Northern Harriers stood in stark contrast to the brilliant white of her prey. Yank! More feathers flew! My friend asked how in the world this medium-sized raptor could have brought down an animal more than three times its own size. Yank! White down floated through the air. I explained about the opportunistic nature of all raptors, taking food that is easy versus fresh. Yank! White fluff surrounded the two birds. Perhaps the snow goose died of natural causes. Yank! I wondered if the diligently plucking hawk would ever reach the flesh of the goose. Yank, yank! Would a hungry Bald Eagle notice the growing pile of white that surrounded the brown? Surely, the harrier, weighing less than two pounds, would be no match for a predatory bird five times its size. Yank! We never knew the final outcome. Eventually, we tired of watching the slow motion drama, and moved on to another area, leaving the bird to her feast.

Not just vultures, known for their scavenging habits, but all raptors and almost all species of predatory animals are opportunistic feeders. Although hawks, eagles and falcons all take live prey, they also scavenge, steal from others and, in general, get food the easiest way possible. At crowded winter roosts, birds can easily spread disease, particularly among waterfowl that gather by the tens of thousands in a single pond. Avian cholera may very well have been the final straw for the goose that had flown south from its Arctic breeding grounds.

Adult male Northern Harrier.

Formerly known as the marsh hawk, the northern harrier hunts primarily on the wing and may cover up to 100 miles per day. Its normal prey, consisting mostly of rodents and small birds, is detected using extremely sharp hearing, facilitated by a pronounced facial disk that helps to direct sound toward its ears. Long yellow legs help it to snatch prey from tall marsh grasses. Commonly seen soaring low to the ground, coursing back and forth over marsh, field, or pastureland, the harrier holds its wings in a shallow “V”, also called a dihedral. The slender-bodied hawk has a long tail and wings, and a conspicuous white rump patch, making it one of the easier hawks to identify.

However, males and adult females are strikingly different. The males are a gorgeous shade of blue gray on their backs, white below with black wingtips, and lemon yellow eyes. Females and young of both sexes are similar with brownish backs, buff-colored undersides which are streaked in the adult females and solid in the juveniles. Males often tend to be found in more upland habitats, whereas females and young frequent lowland areas and marsh habitats.

Adult male Northern Harrier viewed from below.

The northern harrier is found worldwide. There are estimated to be more than 111,000 individuals in North America, breeding primarily in dense, tall marsh grasses, hence their common name, Marsh Hawk. The scientific name is Circus cyaneus which is derived from the the Greek words kirkos, meaning a circle, a reference to the bird flying in circles, and cyan, a blue color referring to the color of the male bird. Harrier is from the Old English word hergian, which means to harass, ravage, or plunder.

Harriers roost and nest on the ground, often in groups in a traditional location. Most males are mated to one or two females at the same time. Some males pair with up to five mates in a season. Females incubate the eggs and brood the offspring, while the male provides the bulk of the food for his mates and their nestlings.

Female or juvenile Northern Harrier, showing the prominent white rump patch.

Historic populations were considered abundant and widespread, but declines have been observed in recent decades. In 1972, this species was placed on the American Birds' Blue List and has remained there since. Declines were primarily due to a loss of breeding habitat and the effects of pesticides. Reforestation, filling in of wetlands, changes in land use, and urban and industrial development in coastal areas all contributed to habitat loss.

During the early-mid 1900s, rampant shooting of all raptors, then considered vermin, also contributed to declines. Attitudes changed and raptor persecution subsided, particularly for the littlish hawk known for dining on the small rodents so disliked by most humans. Subsidence; however, does not spell an end to raptor persecution, still practiced but relegated to shadowy corners.

Photo by Pete Jungman, a falconer in southern New Mexico.

It was 2009. I received a photo of a beautiful male harrier, shot dead; its lifeless body hung on a fence right next to a sign that said “no hunting”. A littlish raptor, minding its own business, helping to keep our rodent population in check.