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Late Migration Mountain Musings

By Dr. Laurie Goodrich, Director of Long-term Monitoring
Hawk Mountain Sanctuary

“… break clear away, once in awhile, and climb a mountain or spend a week in the woods. Wash your spirit clean.”  - John Muir

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Migration flow slows in late November and December, with some days seeing barely a trickle.  But, nearly half the birds we count can be eagles, bald and golden.  Because thermals are rare, the eagles hug the ridge so close that they seem to barely clear the treetops. And, late season days are the only time I have ever seen a northern goshawk or northern harrier strafe the decoy owl.  December is often the best time to see rough-legged hawk, an arctic nesting species that rarely visits Pennsylvania, and one of the rarest raptor migrants. And, northern nesting songbirds such as red and white-winged crossbills are often only seen on these late season days.  Despite these exciting possible sightings, the visitor numbers diminish drastically at this time and counters are often found alone on the rocks.

Laurie scans the sky for migrants from atop North Lookout.

Laurie scans the sky for migrants from atop North Lookout.

Thanksgiving Day, November 23 2017: My sister calls me 9 am.  She asks “where are you having thanksgiving dinner?” I tell her I am going to count hawks in afternoon, though a volunteer is working there this morning.  She is audibly horrified, “they make you count on a holiday? “

“Well…” I say, “ I cannot ask a volunteer to be there, although one is there for the morning. And, other staff have covered other years so it is my turn….” She is quiet and I can tell she is feeling sorry for me, so I say, “and the birds still fly south even on holidays.”  

Secretly, I don’t tell her I am looking forward to my afternoon “on the rocks”.  Later that day I count nine red-tailed hawks and an adult bald eagle gliding south and greet nearly 100 visiting hikers on a sunny Mountain day, sharing my Thanksgiving pumpkin bread. 

Since the 1980s, Hawk Mountain staff and volunteers have manned the North Lookout daily from mid-August through mid-December for the annual autumn migration count.  However, in the early years the season began September 1st and ended November 30th. As we learned more about raptor migration timing, we realized a longer season was needed to fully sample the raptors, particularly eagles and buteos, so we extended the hawk count. 

An immature bald eagle soars past the lookout. 

An immature bald eagle soars past the lookout. 

Bald Eagles have a bi-modal migration with two peaks, one in late August or early September and one in November.  The early eagles are the southern nesting race, that begins nesting in late fall in southern states, while the later birds are the northern bald eagles that nest in New England, Mid-Atlantic and northward.  The northern birds often do not move south in large number until waterways start to freeze up north.  If we have mild autumn weather, we often can have double-digit daily counts of bald eagles into mid-December, which for a species where we record 300 to 500 annually can make a large difference in annual totals.  Golden eagles also can be observed into December with the golden-tinged adults more likely at this time.  Add in an adult goshawk or rough-legged hawk and you have the makings of a great day.

Late season counting is also a great time to ‘wash the spirit clean’ as John Muir states.  The forest is often quiet save for the occasional common raven or pileated woodpecker call.   The skies can be still, save for the occasional raptor or skein of snow geese or tundra swan passing by.  When the sun hits the rocks, sometimes frosted with snow, the peace and beauty of the Mountain can recharge.  Though I hesitate to share this secret of Hawk Mountain, these late season days are worth a few hours time, whether there are migrating raptors or not.    

On that note, happy holidays everyone, and be sure to join us in the Spring!

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Research Serendipity

By JF Therrien, Senior Research Biologist
Hawk Mountain Sanctuary

Hawk Mountain has a rich research and monitoring history. For several decades now, on-staff researchers have been carrying the torch, keeping numerous inestimable monitoring projects going. The migration counts conducted at Hawk Mountain indeed represents the longest running raptor monitoring project in the world.

JF reviews American kestrel nest box data with summer intern Jenna Schlener. Photo by Gigi Romano. 

JF reviews American kestrel nest box data with summer intern Jenna Schlener. Photo by Gigi Romano. 

Starting some 80+ years ago, the counts were first designed to assess the usefulness of the protection offered by the newly created Sanctuary. Not long after, Hawk Mountain's curator Maurice Broun and others realized the invaluable long-term dataset that those counts represent and they could be used to study population trends of 16 North American raptor species. Then in the mid 1950s, Alex Nagy, then Hawk Mountain's assistant curator, installed a few bird boxes on his farm to see if he could get American kestrels to use them. What most likely started as a humble backyard experiment resulted in what is now the American Kestrel Nest Box Program, which will proudly celebrate its 65th anniversary next spring.

Research and monitoring projects sometimes begin after a carefully designed approach. However, in reality, many such projects simply start serendipitously, as in the previous examples. Traveling around Hawk Mountain to visit the 125 man-made nest boxes of the American Kestrel Nest Box Program during summer 2017, we noticed odd and conspicuous behaviors of bigger, darker birds. Indeed on distinct occasions, black vultures would suddenly appear flying low overhead or even flying out a window from the very barns our kestrel nest boxes are attached to. At that point, we had little doubt; those vultures are likely using the building to nest.

JF holds a newly tagged black vulture named Versace. Photo by Rebekah Smith. 

JF holds a newly tagged black vulture named Versace. Photo by Rebekah Smith. 

From a research point of view, having access to nest sites is highly valuable. In addition to being able to handle adults and chicks to assess their life history traits (body condition, growth rate, disease prevalence, etc.), monitoring nesting activities allows us to assess breeding success and breeding rate, age at first breeding, and nest site fidelity on the population level over time. Those aspects are all immensely important to understand the complete cycle of individuals that compose populations.

Finding this access to several nests for any raptor species is challenging, because individuals are often territorial. Their nests occur at low density and are usually concealed. Therefore, monitoring nesting raptors often becomes an unrealistic task, given the time required and the area that would need to be covered to locate a fair number of them. A good breeding monitoring project requires a relatively easy way to access several nests across a relatively small area to allow researchers to visit them periodically.

Black vulture chick found in a local barn. Photo by J. Dallas. 

Black vulture chick found in a local barn. Photo by J. Dallas. 

During summer 2017, our team found just this. We were able to successfully monitor 3 black vulture nests that we found without even searching while checking our kestrel nest boxes. Those birds were using Pennsylvanian barns just like giant man-made nest boxes, and thankfully they were all in a relatively small radius around Hawk Mountain.

This project has just begun, and we are now looking to double or triple the number of monitored nests in the coming years. So if you notice black or Turkey vultures flying out of abandoned buildings or barns, please let us know. We would be thrilled to add new nest locations to our newly-born monitoring program.

Tagged black vulture. Photo by Holly Merker.

Tagged black vulture. Photo by Holly Merker.

By using individual markers (such as wing-tags and telemetry transmitters), we will be following the where and wherefore of those individual birds through their lifetime. Anytime you see a vulture, keep an eye out for wing-tags (a brightly colored tag showing a distinct number). Any sighting of a tagged individual represents important information for locating roost sites, feeding hot spots, survival rates, and dispersal behavior. Help and support these studies by reporting any sightings at this link.

Monitoring programs such as these are an essential part of conservation science: they form the backbone of long-term population assessments. They allow researchers to keep track of historical population size and productivity in order to identify declines in a timely fashion and become aware of problems that otherwise could have gone undetected.

To learn more about our work with North American vultures or any other species of raptors, or if you wish to support our monitoring efforts financially, contact me at therrien@hawkmountain.org.

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