Biology Commons^™

American Kestrel Migration: Insights And Challenges From Tracking Individuals Across The Annual Cycle, Anjolene R. Hunt, Jesse L. Watson, Jason M. Winiarski, Ron R. Porter, Julie A. Heath

Biology Faculty Publications and Presentations

Natural variation in migratory strategies across the range of the American Kestrel (Falco sparverius) creates a unique opportunity for comparative research of annual cycles. However, it can be logistically and technically challenging to track such a small but highly mobile species. We tagged American Kestrels with light-level geolocators or satellite transmitters with the aim of estimating migration timing and connectivity, and we monitored a subset of satellite-tagged individuals during the breeding season to assess transmitter function and wear. We recovered geolocators from six of 49 (12%) tagged individuals. One geolocator-tagged individual migrated approximately 1235 km from its Idaho …

Long‐Distance Natal Dispersal Is Relatively Frequent And Correlated With Environmental Factors In A Widespread Raptor, Hanna M. Mccaslin, T. Trevor Caughlin, Julie A. Heath

Biology Faculty Publications and Presentations

1. Dispersal is a critical process influencing population dynamics and responses to global change. Long‐distance dispersal (LDD) can be especially important for gene flow and adaptability, although little is known about the factors influencing LDD because studying large‐scale movements is challenging and LDD tends to be observed less frequently than shorter‐distance dispersal (SDD).
2. We sought to understand patterns of natal dispersal at a large scale, specifically aiming to understand the relative frequency of LDD compared to SDD and correlates of dispersal distances.
3. We used bird banding and encounter data for American kestrels (Falco sparverius) to investigate the effects of …

Determination Of The Summer Origins Of American Kestrels ( Falco Sparverius ) Wintering In Northern And Central Illinois, Taylor P. Joray

Theses and Dissertations

The seasonal and interannual movements of the American Kestrel (Falco sparverius) are not fully understood. Although one of the most widespread and abundant raptors found in North America, information on where many populations summer and overwinter is lacking. We used stable hydrogen isotope values obtained from feathers (δ2Hf) of known origin to create age-specific calibration functions for juvenile and adult American Kestrels. We then used these calibration functions to determine the most likely summer origins of the American Kestrels that wintered in northern and central Illinois during 2015-16, classified these individuals as year-round residents or wintering migrants, and validated these …

Commentary: Research Recommendations For Understanding The Decline Of American Kestrels (Falco Sparverius) Across Much Of North America, Christopher J.W. Mcclure, Sarah E. Schulwitz, Richard Van Buskirk, Benjamin P. Pauli, Julie A. Heath

Biology Faculty Publications and Presentations

Across much of North America, populations of American Kestrels (Falco sparverius) have been in decline for decades (Farmer et al. 2008, Farmer and Smith 2009, Smallwood et al. 2009a, Paprocki et al. 2014, Sauer et al. 2014). Hypothesized causes of kestrel declines include predation by Cooper's Hawks (Accipiter cooperii; Farmer et al. 2008), pathogens (e.g., Nemeth et al. 2006), habitat loss (Sullivan and Wood 2005, Farmer et al. 2008, Bolgiano et al. 2015), pesticides (Smallwood et al. 2009a, Rattner et al. 2015), and climate change (Steenhof and Peterson 2009b), yet no hypothesized factor has been supported …

Earlier Nesting By Generalist Predatory Bird Is Associated With Human Responses To Climate Change, Shawn H. Smith, Karen Steenhof, Christopher J.W. Mcclure, Julie A. Heath

Biology Faculty Publications and Presentations

1. Warming temperatures cause temporal changes in growing seasons and prey abundance that drive earlier breeding by birds, especially dietary specialists within homogeneous habitat. Less is known about how generalists respond to climate-associated shifts in growing seasons or prey phenology, which may occur at different rates across land cover types.
2. We studied whether breeding phenology of a generalist predator, the American kestrel (Falco sparverius), was associated with shifts in growing seasons and, presumably, prey abundance, in a mosaic of non-irrigated shrub/grasslands and irrigated crops/pastures. We examined the relationship between remotely-sensed normalized difference vegetation index (NDVI) and abundance of small …

Effects Of Researcher-Induced Disturbance On American Kestrels Breeding In Nest Boxes In Northwestern New Jersey, John Smallwood

Department of Biology Faculty Scholarship and Creative Works

Nest boxes for American Kestrels Falco sparverius may alleviate local nest site limitation, but there is concern that periodically opening nest boxes or handling adults may negatively affect nesting success. I monitored 536 kestrel breeding attempts ≥1 egg laid in about 100 nest boxes in northwestern New Jersey, 1995-2012. To study return rates, I opportunistically captured adults in nest boxes and marked them with U.S.G.S. leg bands and patagial tags. To examine possible effects of this disturbance, I compared nesting success ≥1 nestling surviving to banding age of marked and unmarked adults. Nesting success was 67% for 270 unmarked pairs, …

Local Recruitment And Natal Dispersal Distances Of American Kestrels, Karen Steenhof, Julie A. Heath

Biology Faculty Publications and Presentations

Variation in recruitment patterns and dispersal behavior can have important consequences for population viability, genetic structure, and rates of evolutionary change. From 1992 to 2006 we studied a marked population of American Kestrels (Falco sparverius) nesting in boxes in southwestern Idaho to identify factors that affect local recruitment and natal dispersal distances. A low proportion (4%) of locally produced kestrels (n = 2180) returned to nest in study area boxes. Offspring of locally produced individuals were 3.1 times more likely to return than offspring of parents that did not hatch in study area boxes and, independent of …

Influence Of Latitude On The Winter Abundance Of Red-Tailed Hawks (Buteo Jamaicensis) And American Kestrels (Falco Sparverius) In Illinois, Given Harper, Anna Groves, Vic Berardi, Paul Sweet, Jance Sweet, Angelo Capparella

Scholarship

We use five years of data from 18 routes surveyed to determine the temporal stability of a first reported 100 years pattern, and reconfirmed that the abundance of winter 50 years ago tailed Hawk and American Kestrel decreases with increasing latitude, being more high in the central regions of Illinos in the northern regions. Trained volunteers conducted sampling ( n  = 143) a month driving along selected routes from December to February, from 2004-2005 to 2008-2009. We found significant increases in the abundance of both species from the northern regions to the central regions of Illinois. No significant effects of …

Influence Of Latitude On The Winter Abundance Of Red-Tailed Hawks (Buteo Jamaicensis) And American Kestrels (Falco Sparverius) In Illinois, Given Harper, Anna Groves, Vic Berardi, Paul Sweet, Jance Sweet, Angelo P. Capparella

Given Harper

American Kestrel Reproduction: Evidence For The Selection Hypothesis And The Role Of Dispersal, Karen Steenhof, Julie A. Heath

Biology Faculty Publications and Presentations

Many hypotheses attempt to explain why younger, less experienced birds have relatively low reproductive output. We evaluated reproductive patterns of marked American Kestrels Falco sparverius nesting in boxes in southwestern Idaho from 1992 to 2006 to test predictions of these hypotheses. Results were consistent with the selection (differential mortality) hypothesis and did not support the constraint, restraint or recruitment hypotheses. Most known-age Kestrels nested in their first year of life, and there was no apparent short-term or long-term reproductive advantage to delayed breeding. The number of years that Kestrels nested in study area boxes ranged from 1 to 6 years, …

Corticosterone Levels During Nest Departure Of Juvenile American Kestrels, Julie Heath

Biology Faculty Publications and Presentations

Many avian behavior patterns, such as breeding, migration and territoriality, are correlated with changes in hormone levels. Elevated levels of corticosterone, an adrenal steroid hormone, are associated with increased foraging and increased activity levels in birds. Young birds about to take their first flight may benefit from elevated plasma corticosterone levels that facilitate locomotor activity and foraging behavior while they are developing flight and hunting skills. I examined the relationship between corticosterone levels and the timing of nest departure in nestling American Kestrels (Falco sparverius). American Kestrels are cavity nesters and typically depart from the nest between 25-30 …