Wednesday, February 27, 2019

Winter of the Pine Grosbeak

By Anna Morris
Lead Environmental Educator

For many of us at VINS, this winter has been remarkable. In addition to the cold, snow, and ice, the Center for Wild Bird Rehabilitation has seen record-breaking numbers of patients. But one of the most interesting things about those patients was who they turned out to be.

Last winter the northeast experienced an irruption—a term biologists use to describe a sudden change in the population density of an animal—of Snowy Owls. Large numbers of these normally arctic tundra-dwelling raptors found themselves moving south through the United States, looking for open territories and good hunting grounds for small rodents and birds. This winter we are once again experiencing an irruption, but this time of boreal songbirds.

Adult Male, wikimedia commons
Boreal songbirds are birds that breed in, migrate through, or otherwise rely on North America’s boreal forest habitat, according to the Boreal Songbird Initiative. This unique habitat, consisting of mostly spruce, pine, and larch trees, covers 1.5 billion acres of land in Canada and Alaska. The boreal forest not only provides a safe haven for more than 300 bird species and large mammals like caribou and wolves, but the trees sequester large amounts of carbon dioxide from the atmosphere, slowing the effects of climate change.

Evening Grosbeaks, Bohemian Waxwings, Common Redpolls, and Pine Grosbeaks are among the boreal songbird species that bird-watchers all over Vermont have been seeing in unusually high numbers this winter. Professional “finch forecaster” Ron Pittaway of the Ontario Field Ornithologists documents the abundance of boreal bird food crops like conifer seeds and berry-bushes each winter, and predicted that these four species would be abundantly seen due to the low amount of their normal food resources in the summer of 2018.

He appears to have been exactly right. At the VINS Center for Wild Bird Rehabilitation, we have seen 7 Pine Grosbeaks as patients since the beginning of December 2018. (In 2017 and 2016, we saw none at all). Pine Grosbeaks are large, frugivorous (“fruit-eating”) finches, a food source which is highly variable year-to-year, and so occasionally drives them to seek out more resources further south than their normal range. Their 10 inch length and 2-3 ounce bulk may not seem “large”, but you might spot Pine Grosbeaks foraging in large flocks in the winter for nuts and seeds as well. Their scientific name, Pinicola enucleator, means “pine tree dweller, who removes the kernel”, as from seeds.
Adult Female, wikimedia commons

Of our 7 Pine Grosbeak patients this winter, nearly all came in with head trauma, which was likely sustained from colliding with windows. These northern birds have little experience with human settlements, and clear glass confuses them, causing injury. There are many ways to minimize window collisions by birds, and save lives. Putting up ultraviolet reflective stickers or protective screens will help birds recognize an unsafe place to fly.

Our patients in December came from towns farther north in Vermont, and those recent comers have been from right at our latitude, so it has been interesting to track the southward movements of this species in our own state. Three of our Pine Grosbeak patients were able to be released back into the wild, and one young male has joined our resident songbirds on exhibit at the VINS Nature Center.

Stop by VINS soon and meet our newest songbird educator, Hanover. Hanover the Pine Grosbeak came into our care on January 17th, 2019 with a fracture to his left radius/ulna (forearm bones) near the wrist. Though he was in a body wrap for a week to try to heal the fracture properly, it was deemed too severe for release as he is unable to get enough lift for flight even after 3 weeks of healing—bird bones heal a lot faster than humans, and so by this point we know that Hanover’s injury is permanent. He sits near the top of the enclosure, and we’re sure he’s eager meet his new fans!

Monday, February 18, 2019

Meet Windham!

by Bren Lundborg
Wildlife Rehabilitator

Windham, a female Cooper’s hawk, was brought to the Center for Wild Bird Rehabilitation in early February of 2017. She was still in her juvenile plumage and having a rough first winter. Cooper’s hawks often injure themselves due to their aggressive hunting style (one study found over 20% had old healed fractures), and the first winter for any raptor is a difficult trial. When Windham arrived, she was coated in oil, had several puncture wounds around her pelvis and was not standing or able to properly use her feet. Fortunately, she was in good body condition, and after a day of stabilization with warmth, fluids and pain medications, rehabilitation staff was able to clean her wounds and give her a bath to remove the oily substance.

Windham, covered in oil and struggling to stand before her first bath.

The next morning, although she was standing, she was shaking and weak, clearly struggling to keep herself up. Most of her toes curled underfoot. This indicated to rehabilitation staff that she likely had some neurological damage, which may have several potential causes. She may have ingested some of the oil and been suffering from toxicity. The wounds around her pelvis were in the area where nerves from the spinal cord branch out to the legs, and may also have been causing limb issues. To complicate matters, Cooper’s hawks often fly into windows while chasing other birds, so Windham may also have had some previous head or spinal trauma that had led to her current condition. Over the next 10 days, she continued to receive supportive care, including fluids, pain medications and antibiotics for her wounds, as well as twice-daily hand feedings until she began eating on her own. During that time, it took two more baths to get her clean, and several more sessions of cleaning and removing dead tissue from her wounds to allow them to heal quickly and properly. After five days of care, she was standing on her own, but her foot posture was still not improving. We taped flat “shoes” to her feet and began physical therapy to help improve her posture and foot use.

Windham being bathed. Several tubs of soap and rinses were used to get rid of the oil.
The hood over her eyes serves to reduce stress during these procedures.

Finally, after almost two weeks of care, she began eating on her own, and her wounds had healed nicely. Despite daily physical therapy sessions, which involved flexing both feet and each individual toe, she had shown little improvement; she was able to stand but had almost no gripping strength. Still, staff persisted, and after a few more days she started to show some gripping strength. We then moved her to a larger enclosure to see how she was able to get around, and saw she was able to perch and use her feet to hold down food while she tore at it with her beak. Gradually, her gripping strength improved.

Raptors have a behavior called “footing” when attacking or defending themselves, in which they grab their target with their powerful taloned feet. Obviously, it is not a good thing to be footed by a raptor because their long talons can cause significant damage. Around the three-week mark of physical therapy, a coworker exclaimed, “She’s footing me!”

 “Awesome!” I responded (again, this is normally a very bad thing). It was not a powerful grab, and my coworker was unharmed, but the incident showed that Windham’s strength was improving. After almost a month of physical therapy, her feet were finally strong enough to end physical therapy.

Windham clean and dry after several days of care.

Unfortunately, when we brought Windham out to the flight cage, the results were very disappointing. She was only able to glide down from her perch and was not able to get any lift when leaving the ground. It seemed that her neurological damage had also affected her wings. She was unable to extend her wings fully, and even after a long period of rehabilitation and continued exercise, she never regained the ability to fly well. Additionally, we suspected because of her behavior she had some persistent brain damage. A falconer I know aptly described Cooper’s hawks as “bonkers”, as they will throw themselves into a wall or ceiling to try to get away as soon as they see you. However, Windham would sit still on her perch and allow staff to walk up and place food right on her feet. When Windham was stressed, her left foot would clench uncontrollably, a persistent neurological defect from her injuries. Because of these conditions, we made the decision that she was non-releasable.

Windham has now taken up residence for the winter in our broad-winged hawk enclosure. The broad-winged hawks spend the winter indoors because in the wild they would be wintering down in Central America. Windham settled down quickly, even eating on the first night in her strange new setting. She has undergone her first molt into adult plumage, and her eyes have begun to turn from their juvenile yellow color to the fierce red of a mature Cooper’s hawk. While we also have a male Cooper’s hawk, we cannot house them together for the male’s safety. Windham is over one-and-a-half times his size, and females have evolved to hunt birds that are often similar in size to male Cooper’s hawks. In the wild, males must approach females cautiously, and may often present them with a gift of food and wait for them to accept it before coming near. Life is dangerous for Cooper’s hawks, male and female alike, and while Windham may not return to her wild lifestyle, she will continue to inspire and educate people for years to come.