Local and Regional Research Projects

A brief abstract on each of the Sanctuary's 13 local and regional research projects listed below. For more information, call the Acopian Center for Conservation Learning at 570-943-3481.

Project: Autumn hawk migration count
Abstract: Hawk Mountain has monitored the species and numbers of autumn migrant hawks passing by its North Lookout since September 1934. Raptor migration at the North Lookout has been monitored on a daily basis, excluding rainy days and the World War II years of 1943, 1944, and 1945. Raptor migration at the Sanctuary's South Lookout has been monitored intermittently since 1966. Hawk counts and weather conditions were recorded on a daily basis prior to 1966; since 1967 all data are recorded on an hourly basis. Counts usually begin at 8 a.m. and end at 5:30 p.m. EST. One, two, or more staff or volunteer counters are responsible for each day's count. Coverage was expanded in 1980s to include late August and early December migrants. Age and sex of migrant hawks has been recorded consistently since 1985, and intermittently prior to 1985. This database represents the longest record of hawk migration anywhere in the world.

Project: Spring hawk migration counts
Abstract: Spring hawk migration was monitored for five years (1982-1986) to assess the value of Hawk Mountain as a spring migration monitoring site. The count was reinitiated in 1998. Data on species and numbers of migrants are recorded daily from 1 April through 15 May. Counts usually begin at 10:00 a.m. and end at 4:00 p.m. Sanctuary interns, staff, and volunteers conduct the counts.

Project: Autumn migration counts of non-raptors
Abstract: Observers conducting the fall raptor-migration count have recorded non-raptor migrants passing the North Lookout since 1934 for some species and since 1983 for most species. In early years, peak flights were noted by all observers, and some observers recorded daily counts. Since 1983, all birds and monarch butterflies have been recorded consistently each year. Dragonfly migrants were recorded one year. Counts are compiled on a daily basis, except for 1985 and 1991 through 1993 when hourly counts were recorded for Ruby-throated Hummingbirds, monarch butterflies, and dragonflies. Prior to 1988, for some species, only daily presence-absence data is recorded.

Project: American Kestrel (Falco sparverius) reproductive ecology
Abstract: Studies of American Kestrel (Falco sparverius) nesting success in the farmland surrounding Hawk Mountain Sanctuary date from the 1960s, nest boxes for kestrels were first erected in the area. Current efforts, which were expanded considerably in 1986, focus on detailing the occupancy rates, nesting success, and distribution of individually marked kestrels nesting in more than 200 nest boxes scattered throughout a 1,500-km2 study site surrounding the Sanctuary. Wooden nest boxes, most of which are attached to trees in open farmland, are checked regularly following cleaning in March each year until the young fledge in June and July. All nestlings are banded with numbered U.S. Fish and Wildlife Service aluminum bands, and most adults are color banded with a unique combination of three plastic color bands and a numbered NBS aluminum band. The former enables us to determine the subsequent one-site breeding status of birds born in the area, and the latter the lifetime reproductive success of individual adults.

Project: Winter ecology of American Kestrels (Falco sparverius)
Abstract: American Kestrels (Falco sparverius) overwinter in the farmland surrounding the Sanctuary in large numbers. Some of the birds represent resident breeders who remain in the area year round; others are migrants that breed farther north. The extent to which residents and migrants interact during the nonbreeding season is being investigated. From November to March each year kestrels are trapped and color banded in a 1,500-km2 study area of farmlands surrounding the Sanctuary. Each bird receives a unique combination of three plastic color bands and a numbered aluminum National Biological Survey band. Weekly to semimonthly surveys along a 45-km study route in the Kempton Valley, east of the Sanctuary, and less regular surveys of the entire study area, are used to monitor kestrel activity and to determine the extent of home ranges of individual birds, as well as the extent to which gender and migratory status affect habitat use.

Project: Kempton Valley raptor-community habitat use and social dynamics
Abstract: At least 12 species of raptors and New World vultures (Osprey [Pandion haliaetus], Bald Eagle [Haliaeetus leucocephalus], American Kestrel [Falco sparverius], Merlin [F. columbarius], Northern Harrier [Circus cyaneus], Sharp-shinned Hawk [Accipiter striatus], Cooper's Hawk [A. cooperii], Northern Goshawk [A. gentilis], Red-tailed hawk [Buteo jamaicensis], Red-shouldered Hawk [B. lineatus], Black Vulture [Coragyps atratus], Turkey Vulture [Cathartes aura]) have been seen during roadside counts in the Kempton Valley. Weekly to semimonthly surveys along an established 45-km study route in the Kempton Valley, east of the Sanctuary, during which one or two observers travel at 15-40-kmh-1 while strip-censusing birds within 0.4 km of each side of the road, are used to collect population and behavioral data. The species, gender [if possible], age [if possible], band status, geographic location [to nearest quarter km2], vegetation cover, and behavior of the bird are recorded for each individual encountered. This project, which began in the mid-1980s, is designed to monitor the seasonal changes in abundance and distribution of these species, their habitat use and their social interactions. Current efforts focus on documenting the extent of behavioral interactions between resident birds, such as American Kestrels and Red-tailed Hawks, and on autumn migrants that stopover in the area.

Project: Forest fragmentation and nesting Ovenbirds (Seiurus aurocapillus)
Abstract: Declines in abundance of forest-interior, Neotropical migrant songbirds nesting in fragmented forests were well documented by the early 1980s. Our research focuses on defining the mechanism for that decline in a model forest-interior species, the Ovenbird (Seiurus aurocapillus), in eastern Pennsylvania. Male reproductive success and return rates have been monitored annually since 1988 on two continuous forest sites on Hawk Mountain, in eight forest fragments from 1989 to 1997, and near forest openings on and off-site from 1992-1999. To-date, 316 Ovenbirds have been color banded: 207 on the Sanctuary, 67 in forest fragments and 42 near forest openings off-site. Population measures are compared to landscape variables such as vegetation cover, forest size, distance from continuous forest, and percent forest cover surrounding the study site. Other aspects investigated include territory size, density (all birds), forest-floor insect abundance, and predator abundance. Reproductive success is monitored by color banding all territorial males on the study plots and conducting regular spot-mapping censuses to determine mating success and presence of fledglings. Tape playbacks are used to relocate individuals during a visit if necessary. Behavioral patterns such as food carrying and alarm calling are also recorded. At least three to four visits during fledging period are performed before a male is determined unsuccessful.

Project: Butterfly count
Abstract: The annual butterfly count began in 1992 following the methods and format of the North American Butterfly Association. The count circle, centered on the Pinnacle, is the same as that used for the Sanctuary's annual Christmas Bird Count. Species and numbers of individuals are tallied, as well as the hours and miles expended by each active group. General weather conditions also are recorded. Primary effort is focused on public and privately protected lands located within the count circle, e.g. state forest and gamelands, Hawk Mountain Sanctuary, and Leaser Lake. Sanctuary staff and members participate in data collection.

Project: Breeding Bird Census
Abstract: The Breeding Bird Census (BBC) is a standardized monitoring program that estimates breeding bird densities in specific habitat types throughout North America. The program uses the spot-mapping technique, and is best suited for territorial species with relatively small home ranges. Censusing methodology follows the Cornell Laboratory of Ornithology guidelines. Two permanent plots, a ridge-top, south-southwest facing 19.43-ha site, and a low elevation, east-facing 16.9-ha site have been gridded at 30.5-m intervals in the Sanctuary's forest. The habitat in each plot is characterized on a Habitat Classification Form supplied by the Cornell Laboratory of Ornithology. A detailed vegetation survey and vegetation mapping of each plot was conducted in 1989 (F. Watson, unpubl. data).

Project: Winter Bird Population Study
Abstract: Like the Breeding Bird Census, the Winter Bird Population Study (WBPS) is a monitoring program that estimates winter bird densities in specific habitat types throughout North America. In addition, the vegetation of the plot is described. Relatively large areas of a single habitat are preferred for WBPS plots. Censusing methodology follows the Cornell Laboratory of Ornithology guidelines. Two permanent plots (the same two used in our BBCs), a ridge-top south-southwest facing 19.4-ha site, and a low elevation east-facing 16.9-ha site, have been gridded at 30.5-m intervals in the Sanctuary's forest. The habitat in each plot is characterized on a Habitat Classification Form supplied by the Cornell Laboratory of Ornithology. A detailed vegetation survey and vegetation mapping of each plot was conducted in 1989 (F. Watson, unpubl. data).

Project: Hamburg Christmas Bird Count
Abstract: Christmas Bird Counts (CBCs) of birds in early winter are coordinated by the National Audubon Society. The counts occur in late December across North America, northern South America, and the Caribbean and some Pacific Islands. Birds seen or heard within a 25-km (15 mi) diameter count circle are recorded. The Hamburg count circle is centered on the Pinnacle and includes all of Hawk Mountain Sanctuary. Observers range from experienced birders to professional ornithologists. Observer numbers and hours of effort vary among years. Total numbers of birds, total party hours, total party miles, and feeder hours are recorded, as well as owling hours and miles. Data are archived by the National Biological Survey.

Project: Bird species occurrence records
Abstract: Records of bird sightings on Hawk Mountain and surrounding Pennsylvania State Game Lands have been compiled since 1934. The data set began as a card file for Hawk Mountain's bird list. The file includes information on the arrival and departure dates of migrants, high numbers of species, the occurrence of rare species, and other unusual sightings. Since 1980, quarterly reports have been submitted to American Birds. The reports are compiled from many available sources including BBCs, CBCs, WBPSs, Sanctuary feeder reports, migration reports, and staff sightings.

Project: Local weather data
Abstract: Hourly barometric pressure and temperature records from 1974 to 1991 were recorded on Sybron-Taylor Weather-Hawk recording equipment. Since then, temperature, barometric pressure, wind speed, wind chill, and rainfall have been recorded on a Rainwise Weatherstation. Since 1985, rainfall and snow volume has been monitored on an event basis with an all-weather rain gauge made to US Weather Bureau Specifications. The pH of wet precipitation has been monitored since 1985, using guidelines supplied by National Audubon Society as a part of its network of acid-rain monitoring stations. The pH of the Sanctuary's permanent farm pond at Schaumboch's, as well as that of the Little Schuylkill River on the Sanctuary's northwestern border, is measured several times a year.