Birds

Breeding Birds

Many species of songbirds that nest in mature forests of the eastern United States are declining, and it is thought that forest management activities may be part of the cause for the declines, but also may be part of the solution. Since the beginning of the HEE project, field technicians under the direction of Dr. John Dunning of the Department of Forestry and Natural Resources have conducted surveys of breeding birds at the HEE study areas to establish the distribution and abundances of species across the sites and to monitor how the bird communities change in response to forest management.

Since the first timber harvests, we have looked at how birds respond, not only at the specific sites where timber management is conducted but also across the larger spatial scales of the HEE project. Birds are surveyed with 10-minute point counts, during which field technicians record all birds seen and heard within 100 meters of permanently marked locations. Melissa Malloy, who received her master’s degree from the Purdue University FNR department, focused initially on predicted changes in the distribution of common breeders across the study regions in the first years after the harvests, while Patrick Ruhl, who finished a Ph.D. in the same department, and Ken Kellner, a post-doctoral researcher, looked at longer term impacts on both species distribution and breeding success. While all birds are surveyed, some species are of management or conservation concern, and therefore are of special interest. These include migratory songbirds such as the Wood Thrush and Scarlet Tanager, resident species such as Blue Jays that play important ecological roles as nest predators and acorn dispersers, and unusual birds such as the Golden Eagles, which winter locally in the region and the Worm-eating Warbler, a habitat specialist that breeds in the steep forested slopes of southern Indiana. Surprisingly, Worm-eating Warblers have proven to be one of the most common species caught during the breeding season in the clearcuts in later years, when those patches are densely vegetated with early succession shrub and tree species. The role of the young forest habitat in the clearcut patches was a major focus of Patrick Ruhl’s research, which involved banding territorial birds in the clearcuts over several years.

Cerulean Warbler

Project Investigator
Kamal Islam (Retired), Ball State University, (765) 285-8847, kislam@bsu.edu

Dr. Kamal Islam and his students at Ball State University have been studying the Cerulean Warbler in southern Indiana since 2000. This tiny migratory songbird of conservation concern has experienced long-term population declines on its breeding grounds during the past 45 years. We are trying to understand factors responsible for the decline of this species in Indiana, where it is listed as ‘endangered’. Although Cerulean Warblers are generally associated with mature forests, their territories are often characterized by canopy gaps, and these birds are attracted to small openings in the forest created by various forest practices. The presence of Cerulean Warblers in selectively-cut stands suggests that canopy gaps are likely an important habitat variable. Our primary objective in the context of the HEE is to determine how Cerulean Warbler populations respond to different forest treatments by 1) measuring estimates of relative abundance and 2) quantifying reproductive output. An additional research question links the importance of arthropod abundance in oaks and hickories (compared to other tree species), and Cerulean Warbler adult and nestling diet. Recently, we have expanded our research to include fledgling dispersal using radio-transmitters. Evidence from studies of other migratory songbirds suggests that fledglings of mature forest species move into early successional habitats, such as those created by forest harvest. Results from our studies have potential management implications for the conservation of this declining species.

Key Papers:

• Ruhl, P.J., Kellner, K. F., and J.B. Dunning. 2020. Ecological factors explain habitat associations of mature-forest songbirds in regenerating forest clearcuts. The Wilson Journal of Ornithology doi: https://doi.org/10.1676/19-49
• Kellner, K.F., Ruhl, P.J., Dunning, J.B., Barnes, K.W., Saunders, M.R., and R.K. Swihart. 2018. Local-scale habitat components driving bird abundance in eastern deciduous forests. The American Midland Naturalist, 180(1):52-65.
• Ruhl, P.J., Delancey, C.D., and J.B. Dunning Jr. 2018. Roost preference, postfledging habitat use, and breeding phenology of adult female Worm-eating Warblers (Helmitheros vermivorum) on the breeding grounds. The Wilson Journal of Ornithology., 130(2): 397-409.
• Kellner, K.F., P.J.Ruhl, J.B.Dunning, J.K.Riegel and R.K.Swihart. 2016. Multi-scale responses of breeding birds to experimental forest management in Indiana. Forest Ecology and Management, 382:64-75.

Nightjars / ARUs

Project Investigator

Brent Pease, Southern Illinois University, bpease1@siu.edu

Precisely estimating animal abundance at a landscape scale remains a fundamental goal of conservation and management programs. Over the past decade, the use of passive acoustic monitoring (PAM) for surveying wildlife has grown in popularity due to its cost-effectiveness, long recording durations, and ability surveys to be revisited over time. PAM has been used to determine presence or occupancy of species, but estimating abundance and density remains challenging. For example, accurately estimating distance to vocalizing individuals, double-counting, and isolating focal species’ calls in diverse areas can hinder estimates.

Eastern whip-poor-wills (Antrostromus vociferus) are nocturnal aerial insectivores with distinct vocalizations and may be ideal candidates for density estimation using PAM, however, little guidance exists for sampling protocols and analytical frameworks. Additionally, Eastern whip-poor-wills (Antrostomus vociferus) are a species of conservation concern in Indiana and throughout the continental U.S., yet the species’ response to silvicultural techniques remains relatively unexplored. To determine the effectiveness of PAM within the HEE, we are deploying acoustic recording devices (ARUs) across all 9 units during the summer breeding seasons (mid-May – mid July). We program ARUs to record for 4 hours around sunrise (for breeding birds) and 4 hours after sunset (for nightjars). We are also conducting nocturnal point count surveys for nightjars to compare estimates from point counts and PAM surveys. Overall, our objectives are to 1.) assess methods of abundance/density estimation for whip-poor-wills and eventually other breeding bird species using PAM, and 2.) relate silvicultural practices to whip-poor-will abundance.

Density estimation of nightjars using ARUs | PEASE Lab