Wild Notes Winter 2011 edition

Winter 2011

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Cosmo the flying squirrel


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Although grasslands aren't the first thing that comes to mind when you think of Pennsylvania landscapes, the Commonwealth provides habitat for significant numbers of birds that are grassland specialists.  Grassland nesting birds include familiar species such as Eastern meadowlarks and bobolinks as well as species that are less conspicuous such as grasshopper sparrows, savannah sparrows and Henslow's sparrows.  Several raptor species are also considered to be grassland specialists, especially Northern harriers and short-eared owls.  All of these are species that prefer large areas of open grasslands with limited amounts of shrubs and trees.

At the height of deforestation in Pennsylvania about 100 years ago, there were plenty of areas for these birds to nest.  However, through the 1900s the percent of forested land in the state increased and has now leveled out around 62 percent of the state.  We assume that during this period, populations of grassland birds declined in Pennsylvania as woodlands reclaimed the formerly cleared areas.  Interestingly, a new source of grassland habitat for these birds came about in the latter half of the 20"' century as a result of what many consider to be an environmentally damaging land use: surface mining.  Although newer methods of restoring surface mines are in use now, the methods used in the 1970s led to extensive grassy areas where severe soil compaction and other soil quality issues greatly delayed the normal re-growth of woody vegetation.  Thus were born some of the best grasslands in Pennsylvania for rare grassland birds.

The Mount Zion/Piney Tract Important Bird Area (IBA) is the best known of these sites.  It was first recognized as a significant place for grassland birds back in the mid-1980s during the first Pennsylvania Breeding Bird Atlas.  Local atlas contributors documented unusually high numbers of Henslow's sparrows and short-eared owls, both veryrare species in the state, along with lots of other grassland birds.  The only nesting record in the state for dicksissel is from this site.  Seneca Rocks Audubon Society, based in Clarion, Pa., works to protect this land along with several other local organizations.  It took several decades of perseverance to finally accomplish the goal.  In 2005, a total of 2,254 acres became State Game Land 330.

Populations of grassland birds, like this grasshopper sparrow, are declining for a variety of reasons. (Photo: Sarah Sargent)

Funding from WRCP, with matching funds from the State Wildlife Grant program (administered by the Pa. Game Commission) and the Richard King Mellon Foundation, was used to help improve the site for grassland birds starting in January, 2009.  The process began with stakeholders and experts meeting to consider what research and management were needed for the grassland areas, and what the management priorities should be.  Then several research projects and habitat management work took place.

In January 2009, representatives of a variety of organizations - Seneca Rocks Audubon Society, the Alliance for Wetlands and Wildlife, Audubon Pennsylvania, and scientists from Penn State University and Clarion University - met with Game Commission personnel in Clarion to discuss options for management and research at the site.  The discussion centered on Henslow's sparrows, and ultimately it was decided that this species should be the management focus.  This species has "red status" on Audubon’s Watchlist, meaning that it is declining rapidly or has very small populations or limited ranges, and faces major conservation threats. Henslow's sparrow is also listed as a species of high-level concern in Pennsylvania’s Wildlife Action Plan and is estimated to be declining at the rate of 7.92 percent per year based on the USGS’s Breeding Bird Survey.  By managing for this species, the meeting's participants believed that the needs of other grassland species would be met as well.

Approximately 700 acres of the total 2,250 in State Game Land 330 are designated as grassland bird habitat.  However, not all of it is currently suitable for them, primarily because of dense shrubs.  The first major habitat project focused on removing woody vegetation from key areas.  The highest priority area was the hilltop of Mt. Zion, because this 10 to 12-acre area of black locust and other poor quality trees is surrounded by many acres of grass.  By removing the patch of trees, the surrounding grassland would become much more valuable to the sparrows since they avoid nesting near woody edges.  The trees on the hilltop also interrupted the horizon effect; it is thought that grassland birds prefer to see grass meeting the sky without trees intervening.  The patch of trees, along with some shrubs in a nearby field, was removed with bulldozers in March 2009.

This 10-acre patch of poor quality trees was removed to increase grassland bird habitat. (Photo: Gary Edwards)

After the trees were removed, native forbs and grasses flourished, providing good grassland bird habitat. (Photo: Sarah Sargent)

Work also took place to break up the dense fescue grass in one field, because some grassland birds prefer to have patches of bare dirt or sparse vegetation near their nests.  When discussing the site with those who knew it in the 1980s, that was one thing they all remembered; that the grass was not so dense in the early years, and that there were more flowering forbs, such as legumes, which may have provided more insect diversity.  It was decided to try simply scraping parallel strips with the bulldozer.  Four strips, each about 20 feet wide, were put in at 100 meter intervals in one field, along the contour of the hillside.

Funding from WRCP also helped pay for field assistants to do a study quantifying the effect of woody vegetation removal on the breeding success of three species of sparrows. Jason Hill, a PhD candidate at Penn State under Dr. Duane Diefenbach, established two experimental plots at Piney Tract in 2009 as part of a larger study of sparrows on reclaimed mine lands.  In each of these 50-acre plots, all birds of three species (Henslow's, grasshopper and savannah sparrows) were color banded and nests were located.  In all, 215 birds were banded and 32 nests were found.  An additional project that was undertaken by Seneca Rocks Audubon and Clarion University researchers was to survey eight additional fields for grassland birds.  The majority of information on grassland birds from this site came from just two large fields.  Two experienced birders, Gary Edwards and Ron Montgomery, partnered with two undergraduates under the guidance of Dr. Kurt Regester to survey an additional eight fields within the Game Land.  All the fields had grassland bird species in them, and seven of the eight had Henslow's sparrows.

Henslow’s sparrows are a species of high-level concern in Pennsylvania. (photo: Duane Diefenbach)

In January of 2010, another meeting was held to report on what had been accomplished and to plan for the upcoming season.  That year's focus was on clearing additional woody areas while continuing to monitor and control root sprouts from the area cleared the first year.  The main focus was on clearing one of the two experimental sites that Jason Hill and the assistants had studied.  This time around they rented newer, fancier equipment for chewing up shrubs.  Hill randomly chose one of the two sites to be cleared, and this was done in March 2010.

In the 2010 season, Hill and his crew were able to band an additional 203 sparrows and found 28 nests, including some in newly cleared parts of the experimental plot where no nests were found in 2009.  They had numerous sightings of the previous year's birds as well.  They will continue their study in 2011 in order to quantify the increase in density of grassland birds resulting from the change in vegetation.

Jason Hill and Lisa McArthur collect birds in mist nets before banding them. (Photo: Sarah Sargent)

If you would like to visit Piney Tract to see Henslow's sparrows for yourself, check out Seneca Rocks Audubon's website at www.senecarocksaudubon.org.  In the "Go Birding!" section you will find instructions on where to go and what to look for at Piney Tract and other nearby restored mine grasslands.  Be sure to go during the breeding season from May through July.  Believe it or not, these rather drab looking birds bring serious birders from Europe and Canada, in addition to various parts of the U.S.  These birds are that rare!


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