Northern Goshawk Update: Assistance is Still Needed

By dgross March 19, 2018
NG adult female (at nest)

Northern Goshawk female at nest contributed by Steve Hoffman, Audubon Montana.

The Northern Goshawk is one of the state’s rarest breeding raptors and an appropriate symbol of Pennsylvania’s wildest forests. The PA Game Commission is one of the partners in a PA Goshawk Project that also involves Penn State, the PA Biological Survey (OTC), Hawk Mountain Sanctuary, Allegheny National Forest, the Central Appalachian Goshawk Project, DCNR Bureau of Forestry, and some falconers. Chelsea Demarco is a graduate student in Dr. Margaret Brittingham’s lab at Penn State who has been collecting goshawk nesting season records and conducting searches for goshawk territories in various parts of the state with a recent history of goshawk breeding season activity. As I have written in past columns, the Northern Goshawk seems to be declining in the state not only in numbers of breeding pairs but also in size of its breeding range. This is of great concern to bird conservationists in the state and an emerging issue for most states in the Northeast.  We are working together to solve the puzzle of goshawk decline and conservation.  Please help us solve the puzzle and bring more light to the goshawk question.

The project made significant outreach to the public including an article in Pennsylvania Game News, PSO Newsletter, PA birds list serve, PA eBird, organization publications, and hunting and falconry groups. We really got the word out which was made easier by establishing a website for the project.

The PA Goshawk Project worked hard to cover the recent goshawk territories in forested counties. The effort and cooperation were quite impressive. This is especially true since most observers consider goshawk information as confidential so we really worked at sharing information on an “as needed” basis, protecting confidentiality, and avoiding any possible conflicts between the observer / contributor and the research team members. If our sources put limits on information dispersal, we respected those concerns. But, even with that extensive effort the 2017 season results were pretty dismal. There were five basic approaches that included the usual Central Appalachian Goshawk project (led by Dave Brinker) and Allegheny National Forest searches in the Northwestern counties, the two agencies doing searches in areas of interest (Doug Gross of PGC and Aura Stauffer of DCNR), a Kittitinny Ridge search led by Laurie Goodrich of Hawk Mountain, and the Penn State crew covering many locations with more formal surveys, sometimes with other team members. Many of these surveys were area-searches of locations with recent history of goshawk territorial behavior (nests, calling birds, seen birds) including reports from the public, but there also were more technical surveys using established protocols and audio-lures.

Search Results for Northern Goshawk by the PA Goshawk Project in 2018. By Chelsea DeMarco, PSU

The goal of the 2016 PA Goshawk Project was to conduct 2 protocol surveys at each targeted site. There were 60 sites that were fell in the region that the ANF crew was covering, and 76 were divided between Hawk Mountain and Penn State. Due to the late start, only 8 sites outside of the ANF were surveyed twice and 56 sites were surveyed once, but that is a very big list of sites to survey for a deep forest raptor. In total, there were 10 active territories reported this last season. Around 352 hours were spent using the directed search method to locate nests in recently active territories. Eight nests were found between April and May by surveying historic nest sites using the directed search method. Five were found on the ANF, 2 from falconers and 1 from a goshawk enthusiast. (Most nests had been active in 2016 and the oldest record was active in 2012). Two additional nests were found through contacts in the birding and wildlife community.

Northern Goshawk comparison distribution map from the 2nd PA Breeding Bird Atlas. Its range seems to have shrunk since the 1st Atlas in the 1980s with fewer records in southern, extreme eastern and western part of former range despite greater effort by participants.

There certainly have been declines in the breeding population and range of Northern Goshawk in Pennsylvania. There are suspicions that the 2017 was a particularly poor year for Northern Goshawk, a species known to vary on a year-to-year basis for a variety of reasons. Wet spring weather, low prey populations, human interference, the cumulative effects of forest fragmentation, nest predation, and West Nile Virus are all suspected factors. Some territories are occupied with a nesting pair in one year and not occupied the next even when the site’s condition seems the same and the birds are closely watched. There is evidence that fishers raid some goshawk nests so their increase may be a factor in goshawk decline. There have been declines in some regions over the last two decades, so West Nile Virus and fisher predation are not the only factors at play. The pattern of forest fragmentation, residential and energy industry development, declines in prey species availability, and conifer tree losses may have set the stage for other factors that are getting attention. Persistent research should yield more answers for the decline in goshawks and what we can do to reverse these declines. Certainly, learning where there are goshawk nests will allow the agencies to protect nests from disturbance and increase the potential for nesting and reproduction.  Even nests on public property may not be safe from disturbance.

A Pennsylvania goshawk nest in a large Red Maple surrounded by conifer evergreens. By Doug Gross

On the contrary, goshawk team observers found many other forest raptors in the 2017 surveys. A total of 84 forest raptor detections were recorded with 12 active nests and 3 territories located. Most detections were Red-shouldered and Broad-winged Hawks. This demonstrates that the observers did have success finding forest raptors and that these species are doing comparatively well in the big woods of the state. The 2nd Breeding Bird Atlas also showed increases in other forest raptors that suggest that goshawk has specific challenges or is more sensitive to changes in the landscape than other hawks.  We are trying to find out how goshawk is doing and why it is not doing as well as the other forest raptors. Each good observation helps the research and also increases protections for nesting pairs. We cannot protect a nesting goshawk if we do not know exactly where that nest is located.

Northern Goshawk nest in Allegheny National Forest by Scott Stoleson.

The Pennsylvania Goshawk Project will continue in 2017 with some adjustments. Chelsea Demarco plans to complete a GIS analysis of historic nest sites. In addition, we are currently discussing options that would provide us with some solid data on goshawk abundance and distribution within its apparent remaining core habitat in PA. The Northwestern counties will probably get the most attention but we also will be surveying historic goshawk sites in the Northcentral and Northeastern counties. We urge Pennsylvania birders to look at old goshawk areas that they know about and report their results to the PA Goshawk Project. For more background, I previously wrote about the Northern Goshawk in Pennsylvania in a March 2017 PSO Newsletter Raven Reporter column and in a previous PA eBird story that can be found at https://ebird.org/pa/news/northern-goshawk-reports-needed-for-the-ultimate-forest-raptor/

Northern Goshawk adult, contributed by Steve Hoffman of Audubon Montana.

For more information about the PABS goshawk committee’s research, visit the PA Goshawk Project website at: www.pabiologicalsurvey.org/goshawk. There you can find images and audio to aid identification as well as forms, instructions, and contact information. Goshawk reports can be e-mailed to goshawk@psu.edu. Reports also can be sent by postal mail to Goshawks C/o Dr. Margaret Brittingham, Ornithological Technical Committee, Wildlife Resources, 409 Forest Res. Bldg., Penn State University, State College, PA 16802.  If you prefer to talk by phone, please make phone reports to Laurie Goodrich of the Hawk Mountain Sanctuary at: 570-943-3411×106.  Any goshawk observations during the breeding season, from late March to June, on game lands or where there regulatory enforcement issues, please also include the PA Game commission which is easy to do at pgcgoshawk@pa.gov or send to me at dogross@pa.gov or dagross144@verizon.net.  Reports to either the Pennsylvania Goshawk Project or the Game Commission will be treated as confidential. Since this is a cooperative research and conservation project,  we do share information within the committee if allowed by the conditions set by the contributor of the observation and the location of the observation. We want to assist goshawk through research and cooperation whenever and wherever we can.

Doug Gross

Pennsylvania Game Commission

Odin, a study subject of PA goshawk research and oldest known goshawk in state. By David Brinker.