monitoring

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.

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.