owls

Irruptions and Innovation

By Zoey Greenberg, Science Outreach Coordinator
Hawk Mountain Sanctuary

Stella, a snowy owl tagged by Project SNOWstorm earlier this year.

Stella, a snowy owl tagged by Project SNOWstorm earlier this year.

In 2007, Dr. JF Therrien deployed 12 transmitters on snowy owls on Bylot island in the Canadian Arctic. Snowy owls, like other raptors, can be difficult to monitor due to their territoriality and low densities. Arctic-breeding raptors typically establish nesting sites in remote locations, adding to the logistical dilemma of gaining insight into their life history traits, and the role they play within the Arctic ecosystem.

Satellite transmitters, citizen science, and long-term life history studies are extremely valuable tools that allow researchers to examine the movement ecology of birds, including snowy owls. Mixing and matching these tools can open doors to compelling scientific questions, and in the case of Therrien’s snowy owls, has resulted in papers covering a range of topics. New information on survival, reproduction rate, dispersal of adults, irruptions and winter movements are among recent Hawk Mountain publications that were made possible through this type of innovation. 

Two such papers were led by former conservation science trainees, in collaboration with others, including Dr. JF Therrien. These papers delved into the mystery of snowy owl irruptions, defined as the “massive movement of individuals over large distances, associated with large fluctuations in food supply.” Some of us have been lucky enough to see a snowy owl in Pennsylvania, on those rare winters when the birds venture further south than usual. I myself drove two hours to catch a glimpse, and I will never forget the sight of that owl hunkered down in the middle of a field, glittering in evening light. As I drove away, I couldn’t help but wonder; what brings them here?

Two primary hypotheses have been proposed to explain irruptions; the “lack-of-food” hypothesis suggests that snowy owls leave their normal wintering grounds because of food shortage in certain years. This implies that the snowy owls we see in Pennsylvania should be in poor shape, and likely close to starving. The alternative “breeding success” hypothesis instead links irruptive movements to a surplus of food on the breeding grounds.

A snowy owl that was spotted in a local PA field last year.

A snowy owl that was spotted in a local PA field last year.

Snowy owls specialize in lemmings, a prey resource that occurs in pulses, due to their population dynamics. One year there may be a plethora of lemmings scurrying around the tundra, the next year very few, due to high predation and other factors. Lots of lemmings means lots of chicks, which means lots more owls. The breeding success hypothesis implies that the reason we see snowies in Pennsylvania is because following a high lemming year, there are so many owls dispersing at the end of the summer that some young birds push south.

To add depth to our knowledge of irruptions, Teja Curk, a conservation trainee from 2016, assessed the body condition (mass relative to size) of snowy owls during both irruptive and “regular” years. Teja assessed body condition of snowies on both regular (Great Plains) and irregular (Northeaster North America) wintering grounds, to see whether the birds we see during irruptive years are, in fact, starving. She found that most owls (male, female, juvenile and adult) were in good shape during irruptive years and even discovered that body condition was better on the bird’s irregular wintering grounds. “Good shape” in this context varies depending on sex and age of the bird, however less than 2% of the owls approached the weight threshold that would deem them a starving bird. Her results provide support for the breeding success hypothesis.

Pablo Santonja and Irene Mestre, trainees from 2015, looked specifically at the age of the birds found south during irruptive years. Their results supported the same hypothesis, showing that the majority of owls (up to 90%) seen in eastern North America are juvenile birds, meaning they are less than 1 year of age. As with some other migratory species, the more dominant birds within a population don’t move as far. Adult snowy owls often out-compete young birds, so it makes sense that in a year where adults are laying up to 11 eggs, some of those young owls will need to leave to avoid competition from more successful, experienced adults.

Bylot Island, where the Hawk Mountain team tagged and tracked several snowy owls.

Bylot Island, where the Hawk Mountain team tagged and tracked several snowy owls.

This leads to an interesting point: perhaps these two competing hypotheses are not, as Teja notes in her paper, mutually exclusive. After a highly productive lemming year, many lemmings will be eaten due to a surge in predator numbers, and therefore the next year could produce low lemming numbers. If this happens, snowy owls could be forced to look elsewhere for food. So, it turns out, that both a surplus of food and a lack of food seem to play a role in the patterns of movement among snowy owl populations.

If you ask me, these papers are a beautiful example of the scientific method at work; formulating ideas, testing those ideas, and polishing the conclusions in pursuit of certainty. Hats off to our trainees and their collaborators for hard work and intriguing findings. Teja is currently at the Max Planck Institute for Ornithology in Germany pursuing a PhD. Pablo is living in Spain, and Irene is now returning from three years in Australia.

Both of these papers utilized a data set resulting from a 25 year-long study in which live snowy owls were weighed, sexed, and aged. Christmas Bird Count (CBC) was also a valuable asset in both studies. For those of you unfamiliar with CBC, every winter thousands of volunteers gather together on the same day, collecting bird records within a territory and submitting them to a database that provides an impressive summary of which birds were seen, where, and how many. These papers demonstrate the utility of both citizen science and long-term studies, and in a rapidly changing world, this cross-pollination of resources is critical. We are very proud of our trainees for their hard work, and grateful to citizen scientists around the globe who give their time to participate in the expansion of our raptor knowledge.

Gaining a holistic understanding of an ecosystem requires acknowledgment of moving parts within, not separate from, the whole. Hawk Mountain’s research is part of several collaborative efforts to better understand the role of snowy owls within the big picture, including Project SNOWstorm and the Bylot Island Ecological Studies and Environmental Monitoring.  

Future projects will include building a model that combines reproductive and mortality rates to assess population trends of snowy owls. This past August, three transmitters were deployed on chicks before they left their breeding grounds. Investigating the movement patterns of these birds will hopefully allow for a comparative look at owls throughout the Eastern tundra, Western tundra, and those in between.

Check out Project SNOWstorm’s website (including a blog written by J.F Therrien on the most recently tagged snowy owls in Barrow, Alaska, as well as interactive maps): projectsnowstorm.org/posts/tracking-young-snowies-in-the-arctic/

Across the Pond with Raptor Care Rock Star

By Rachel Spagnola Taras, Senior Educator
Hawk Mountain Sanctuary

Nearly a decade ago, Jemima Parry-Jones (JPJ), Director of the International Centre for Birds of Prey (ICBP) located in Newent, Gloucestershire, United Kingdom, answered an e-mail I sent to her hoping to gain insight on captive raptor management. Not only did JPJ promptly and thoroughly respond to my questions, she insisted that I visit her facility. With the generous support of Hawk Mountain Sanctuary friends Brian and Sandra Moroney, I completed my educational journey across the pond earlier this season to benefit our feathered educators and the volunteers and staff who work together to maintain best practices in raptor care management at Hawk Mountain. Education raptors help to connect learners of all ages to conservation with an up-close look at species that serve a vital role in our ecosytems worldwide. 

Jemima Parry-Jones and a barn owl welcom school children to ICBP.

Jemima Parry-Jones and a barn owl welcom school children to ICBP.

Located in the quaint English countryside, ICBP oversees nearly 300 birds of prey, including a diverse workforce of owls, eagles, vultures, kites, hawks, falcons, and harriers. During my stay, I was treated to a grand tour of the entire facility. Open to the public 7 days per week, 10 months of the year, visitors have the opportunity to see raptors on display in a zoo-like static setting and during multiple free-flighted training sessions throughout the day. During these flying demonstrations, ICBP trainers connect visitors of all ages to a fast-paced, exciting look at natural history in action.

One highlight of my visit was participating in training several  yellow-billed kites by cuing birds to fly over the field in front of visitors and signaling them to return, tossing meat straight up in the air to emulate their natural behavior of grasping prey in flight. Although I do not consider myself athletic, there’s nothing like being watched by countless visitors who are glued to your every move while one of the most famous falconers in the world is narrating and evaluating your meat throwing abilities. With the supportive direction of JPJ, I felt like an Olympian.  

An ICBP staff member monitors the weight of a white-tailed sea eagle.

An ICBP staff member monitors the weight of a white-tailed sea eagle.

In addition to shadowing the husbandry and training of some of the world’s largest and endangered raptors, I learned new techniques and skills to improve communication through body language and clear cues when working with animal colleagues. While working with a massive white-tailed sea eagle, I honed my ability to remain perch-like to provide a stable and trustworthy roost. If you see me lifting weights, you’ll understand why I want to build and maintain a strong  and stable resting place for a bird who weighs over ten pounds.

 Sadly, when visiting the on-site rehabilitation hospital building, I learned more about real-time conservation challenges like the direct persecution of raptors in the community. Unlike North America, migratory birds are not legally protected and are perceived as competition for resources such as small game.  I had the opportunity to meet with law officials who were inspired by Hawk Mountain Sanctuary’s rich history thanks to pioneer conservationists like Richard Pough and our own founder, Mrs. Rosalie Edge.  

On this side of our shared Atlantic Ocean, I remain proud to represent the world’s very first refuge for birds of prey and to help advance our mission by sharing our story and the need for continued research and education worldwide.

Help support our raptor care and public raptor education efforts by donating or becoming a member today.

Springtime in Montana

By Dr. Jean-Francois Therrien, Senior Research Biologist
Hawk Mountain Sanctuary

Spring sunrise in Montana, over the Mission Mountains.

Spring sunrise in Montana, over the Mission Mountains.

It’s spring time in Montana. Well, at least according to the birds. Not that the weather has been any better than in the East lately, but birds are showing definite signs of a change in seasons. Following Hawk Mountain's global and inclusive mission geared toward collaborating with like-minded colleagues and organizations to lead lasting raptor conservation programs, I was recently invited by long-time researcher, collaborator, and friend, Denver Holt, from the Owl Research Institute, to get a feel of the pre-breeding season in his study area in scenic Mission Valley, Montana.

Holt, founder and leader of the Owl Research Institute, has been conducting field-based owl surveys for over 30 years now, including long-term monitoring of snowy owls in Alaska. Thus, there is an amazing opportunity to combine and compare results from our ongoing long-term research project in snowy owl breeding grounds in the Canadian Arctic, and to learn about the population status of this charismatic species across North America.

In addition, spending a few days in the field in Montana allowed us to identify potential projects for future collaborative work. Among them, assessing the pre-breeding condition of individual owls and how it is affected by the previous winter conditions, and then how it relates to upcoming nesting success, is on top of the list. The fact that we know very little of the basic ecology for most of those species is not a surprise for any owl biologist. However, according to any source of available information, several North American owl species are facing an uncertain future. Indeed, population trends of long-eared and short-eared owls are both showing alarming decline on a continental scale. In light of the threats impending on these species, such collaborative research projects have to happen now.

Numerous accounts have recently suggested that to understand the reproductive ecology of any species in order to better protect them, we need to have a holistic view and turn our attention to the non-breeding season. With that in mind, there is an amazing opportunity for collaboration with the Owl Research Institute and their extensive field-based experience.

Dr. JF Therrien (senior research biologist at Hawk Mountain) and Denver Holt (founder and president of the Owl Research Institute) just before releasing a long-eared owl.

Dr. JF Therrien (senior research biologist at Hawk Mountain) and Denver Holt (founder and president of the Owl Research Institute) just before releasing a long-eared owl.

Those few days in Montana confirmed for me that they sure know the ropes of studying owls in the field: before lunch on the very first day, we had already captured and released 5 long-eared owls to assess their pre-breeding condition. We then proceeded to observe a phenomenal amount of great-horned owls (most of them sitting tightly on their nest), as well as short-eared owls flying and displaying territorial behaviors over the grasslands at dusk, among other things.

Research collaborations are an essential part of conservation science. Individuals alone can go a certain way, but with colleagues, we make real change. That is why at Hawk Mountain, we put much value in cooperation, team work, and network building. To learn more about our work with North American owls or any other species of raptors, or if you wish to financially support our research efforts, contact me at therrien@hawkmountain.org.

A Back-to-Back Snowy Owl Adventure

By Rebecca McCabe,  PhD Student, McGill University
Hawk Mountain Research Assistant

The view on Amherst Island

The view on Amherst Island

It was 6:15 a.m., and the sun had not yet come up as we stepped from our cars onto the ferry deck on the ice-covered waters of Lake Ontario. We were on our way to Amherst Island, a 70 square-kilometer island off the coast of Kingston, Ontario, which is a known hotspot for wintering snowy owls and the reason why we were there.

Myself, Jean-François Therrien (Hawk Mountain), Tom McDonald (Rochester, NY), and Dave Okines (Prince Edward Point Bird Observatory) arrived on the island with the hopes of deploying transmitters on snowy owls as part of the collaborative research of Project SNOWstorm (www.projectsnowstorm.org).

The sun rises over the frozen Lake Ontario.

The sun rises over the frozen Lake Ontario.

As the sun finally rose, we were already driving the main roads searching for white silhouettes in the distance. Luckily for us, Amherst had plenty of snowy owls! We estimated over 25 owls on the island, and now all we had to do was trap a few. We came up short in the morning and afternoon, but as soon as the sun started to set, our luck changed. Within 20 minutes both Dave and Tom had trapped an owl.

Snowy owl Stella, a female trapped and tagged by Project SNOWstorm in Amherst

Snowy owl Stella, a female trapped and tagged by Project SNOWstorm in Amherst

We were fortunate to have a wonderful host, Janet, who allowed us to bring the owls back to her place so we could process them out of the cold. The two immature females, later named Emerald and Stella, were in good condition and each weighed over 2 kg making them eligible to receive a transmitter before being released back into the night.

In just a short amount of time we have learned that the neighboring birds  established territories approximately 3 km from one another on the island, and Emerald has spent more time inland whereas Stella has been going offshore onto the ice during the day. I look forward to following these two individuals as they make their way north in the upcoming months.

One week and 2,370+ km later, I am scanning for snowy owls from the passenger seat again, but this time I am looking out on the prairies of Saskatoon, Saskatchewan. My co-supervisor Karen Wiebe (University of Saskatchewan) and I follow behind raptor bander Marten Stoffel in our pickup truck as we search the tops of telephone poles and fence posts. We spent six hours that day driving the survey route and had easily seen over 30 snowy owls. We were also very fortunate to trap and band six, a record day of trapping snowy owls on the prairies for Marten!

Male snowy owl trapped and tagged in Saskatchewan. 

Male snowy owl trapped and tagged in Saskatchewan. 

The next day we decided to go out again to see if luck was still on our side, this time driving about 150 km northeast of where we were the day before. I was shocked at the stark difference between locations and by the lack of owls we encountered on our second day. The habitat appeared similar but we only saw one adult male that afternoon. Marten decided to try trapping it, even though it was a more difficult catch with blustery winds and the male sitting high atop a transmission tower. Moments before calling it quits, I watched intently (and completely mesmerized) as the owl leapt from its perch and with a few strong flaps, came streaming in towards the bal-chatri before getting trapped.

Spending just a few days on Amherst Island and in Saskatoon and getting to see where these owls spend their winter was not only exciting but informative. I was able to observe them on their territories, take note of their favorite perches, and see first-hand the conditions they were in. As I move forward with my PhD at McGill University and analyze the movements of our GPS tagged snowy owls, my time spent in the field has allowed me to gain a better understanding of how these magnificent birds move throughout the landscape, the habitats they occupy, and the threats they face.

Becca with a recently trapped and tagged snowy owl right before release.

Becca with a recently trapped and tagged snowy owl right before release.

To learn more about these efforts or to support the project, visit hawkmountain.org/snowyowls.

Adventures and Advancements in Captive Raptor Management

By Rachel Spagnola, Senior Educator
Hawk Mountain Sanctuary

Rachel and TRC’s Education Program Manager Gail Buhl work through passing off and handling a bald eagle.

Rachel and TRC’s Education Program Manager Gail Buhl work through passing off and handling a bald eagle.

Earlier this season, I had the incredible opportunity to attend The University of Minnesota’s 2017 Care and Management of Captive Raptors four-day comprehensive workshop from October 13-20, funded by a Philadelphia Foundation grant. With over 20 years of “talons-on” experience working with raptors in captivity, I have returned to Hawk Mountain Sanctuary from The Raptor Center (TRC) with a renewed sense of empowerment and motivation to propel our captive management practices to a world class status.

Prior to handling and training birds at the TRC, I successfully completed hands-on medical exams and necropsy under the direction of expert clinic staff. Although far from being Dr. Dolittle, after learning the best practices in diets, nutrition, equipment, and raptor housing, I am eager to implement modifications to provide the highest quality of life for my feathered coworkers.

Rachel assists Hawk Mountain's veterinarian, Dr. Pello, during a routine check up of our red-morph eastern screech owl. 

Rachel assists Hawk Mountain's veterinarian, Dr. Pello, during a routine check up of our red-morph eastern screech owl. 

Hawk Mountain Sanctuary’s Education Department is responsible for a collection of birds that require care and maintenance 365 days a year. In my role as senior educator and lead raptor care manager, I schedule, train, and supervise volunteers ensuring best practices and the safety of volunteers and birds. With the support of my education teammates Erin Brown and Adam Carter, I created a vetting process for volunteers to ensure consistency and high standards of care. Unable to send a text message or call staff when they are ill, we are responsible for feeding, cleaning, conducting routine health checks for the birds year-round. We take this responsibility seriously 24 hours a day, 7 days a week, monitoring bird welfare through polar vortex temperatures, mosquito-breeding season, and beyond. Attending the TRC workshop fostered my deeper appreciation for the role of avian educators as ambassadors for raptor conservation.

We also manage on-going training and enrichment for both the birds and volunteers throughout their tenure, aiming to provide a stress-free environment for our avian educators throughout their lifespan. Although young at heart, several members of our avian education team are entering their “golden years” and have geriatric needs. The HMS avian educators have individual special needs in addition to the natural history requirements of each species.  

Rachel hones her raptor training skills with TRC’s resident red-tailed hawk.

Rachel hones her raptor training skills with TRC’s resident red-tailed hawk.

In recent years, I developed a Raptor Care Advisory Committee consisting of an avian veterinarian, raptor rehabilitator, and professional bird trainer who share their unique knowledge, specialized skills, and experience to meet the needs of our captive raptor management plan. With the guidance of the International Association of Avian Trainers and Educators (IAATE), I’ve created a collection plan, training and enrichment plans, and a retirement position statement to ensure consistency and adherence to our mission of serving as a model facility.

Although the Pennsylvania Game Commission and the United States Fish and Wildlife Service require annual audits of Hawk Mountain Sanctuary’s collection of captive birds, we also undergo a yearly voluntary audit by an outside source. Most recently, my ultimate raptor conservation hero, (after Rosalie Edge, Maurice and Irma Broun, of course), Director of the International Centre for Birds of Prey, Jemima Parry-Jones conducted a thorough exam of all birds and an audit of our enclosures and indoor raptor care facilities.  

I owe a debt of gratitude to Hawk Mountain Sanctuary’s team of volunteers, advisors, staff, and mentors who continue to support me.  When you visit the Sanctuary and enjoy a live raptor program, ‘Raptors Up Close’ or meet one of our ambassadors at a festival or large event, please know that your support makes a positive impact!

Keep Farmland Raptors Soaring

Northern Harrier

Northern Harrier

By Katie Andrews, PA Farmland Raptors Volunteer
Hawk Mountain Sanctuary

Since 2012 Hawk Mountain Sanctuary has been reaching out to Pennsylvania landowners and farmers to help us conserve four species of grassland raptors in decline across the state: American Kestrel, Barn Owl, Short-eared Owl and Northern Harrier.

Female American Kestrel

Female American Kestrel

Participants can report sightings of the four species to the Hawk Mountain Farmland Raptor Database, install nest boxes for Kestrels and Barn Owls, improve habitat for ground-nesting Northern Harriers and Short-eared Owls (e.g., leaving unmown, overgrown pastures), and encourage others to participate by distributing brochures and posters. Because farmland raptors benefit farmers by consuming rodents and insects, many farmers are happy to help and enjoy seeing raptors flying above their fields. To date we have almost 200 landowners signed up and more than 200 volunteers who report sightings of the four birds to us.

In our first two years we were supported by a DCNR PA Wild Resource Conservation Program grant, but in recent years we have sustained our efforts with the help of volunteers and donations from individuals, area businesses, and other birding and conservation organizations.

Barn Owl

Barn Owl

Anyone with an interest in this project can get involved! Report your sightings or help us man a table at local fairs and public events. We would like to expand our outreach to farming communities across the state, so help with distributing brochures and nest box plans or posting posters, installing nest boxes or attending agricultural fairs in your county with a table on farmland raptors is always welcome.

To read more on the project visit the Farmland Raptor Website. You can read descriptions of all four species, download copies of the brochure and newsletters and access the online sighting report form.

For more information: www.hawkmountain.org/farmlandraptors

Contacts: Farmland Raptor Volunteer Katie Andrews at farmlandraptors@gmail.com

 Dr. Laurie Goodrich: 570-943-3411 x106 or Goodrich@hawkmountain.org

Annual Raptor Care & Wellness

By Susan Pello, VMD, MS
Small & Exotic Animal Veterinarian

Hawk Mountain Sanctuary currently has 4 education ambassadors. Each bird is carefully monitored and cared for by the education staff as well as trained volunteers at Hawk Mountain. Our avian education ambassadors are trained to work with the staff to educate the public, and they represent their wild counterparts as they travel near and far. However, every bird requires daily care and yearly examinations. I enjoy travelling out to Hawk Mountain every spring to see the birds. At times, the birds will travel out to me for any issues concerning to the raptor care staff.

So, how do wild raptors become education ambassadors? Due to injury, amputation, blindness or imprinting, raptors that come into a rehabilitation facility are determined to be unfit for release and in turn become captive raptors for education. The federal government mandates specific guidelines and criteria which must be met prior to releasing a bird of prey back into the wild.  In raptors 6 weeks or younger, we worry about imprinting on humans. If this occurs the animal becomes non-releasable. We see imprinting commonly in baby cranes, vultures and other avian species.

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A captive raptor requires yearly exams and wellness blood work just as our companion animals. Raptors are considered wild animals, even in captivity and their care is much different from that of a dog. Birds hide illness and therefore require a physical exam and blood work yearly.  The day to day care, includes monitoring their appetite, weight and activity. When a bird is transferred to a facility, an initial physical exam, x-rays and blood work are performed. During physical examination, I will evaluate the eyes, mouth, ears, listen to the heart and respiratory system and perform a full orthopedic examination. Feather and skin condition is also evaluated.

When housed in a captive setting, especially birds with orthopedic limitations or previous fractures, raptors are prone to feather damage and foot injuries. Together with the raptor care team, I will review options to help improve feather quality, foot care and cage enrichment. At Hawk Mountain Sanctuary, a physical examination is performed, blood is drawn and xrays are recommended. It is also recommended that all captive raptors be vaccinated for West Nile Virus (WNV).  The WNV vaccine is administered once a year prior to mosquito season. This is the only recommended vaccination.

At the time of intake, all of the birds are DNA sexed and this is because our female birds require higher levels of calcium and monitoring for egg laying behavior. The birds can produce an unfertilized egg, without a male present. Currently, all of the education birds at Hawk Mountain are female, except the newest member, a red-morph eastern screech owl.

The red-morph eastern screech owl was recently adopted by Hawk Mountain for education purposes. He has a right wing injury that limits his flight, therefore he has been determined unfit for release into the wild. He received his intake examination in January 2017.  The small owl was found to be dehydrated with multiple broken tail feathers and contracture to his right wing. Despite his severe right wing damage, he is still able to fly a little. During his examination we administered his WNV vaccination and took some blood to evaluate him for any illness.

During my visit, I also had the luxury of examining my favorite great-horned owl. GHOW is at least a 17 year old female who recently started laying eggs. She also has developed some abnormal wear to her beak and receives occasional coping (beak shaping).  

I look forward to my spring visit this year when I will have the opportunity to vaccinate and examine the entire flock of avian ambassadors at Hawk Mountain.