Northern Saw-whet Owl Research at the Sanctuary
The banding of Northern Saw-whet Owls (NSWOs) is entering its fourth season at Indiana Audubon Society’s Mary Gray Bird Sanctuary (MGBS), located in Fayette County, in east-central Indiana. During the banding season of 2017-2018, one NSWO was recaptured at MGBS in the spring of 2018. It had been banded in the fall of 2017. This prompted a question as to whether the bird had been a migrant or resident bird and/or if there were other NSWOs that may have used MGBS as a stopover or overwintering site. Beckett & Proudfoot (2011) analyzed data from the Bird Banding Laboratory that indicated NSWOs demonstrate migration route fidelity despite relatively low recapture rates within a migration season.
NSWOs are known to overwinter in Indiana but little information has been collected regarding the frequency and habitats of these occurances (Brittan, R.A., Meretsky, V.J., Gwinn, J.A., Hammond, J.G., & Riegel, J.K. (2009).
Roosting sites of NSWO are presumed to be partial to pine forests and second growth deciduous forests with relative high density in the understory (Churchill, Wood, & Brinker, 2000). Brinker, et al., (1995) discuss farming practices that have altered the flora and fauna of N. America in the past 300 years; removing former habitats of the NSWO. A question arises as to whether the MGBS property provides a suitable island of mixed forest habitat, amongst a sea of agriculture, for the overwintering of NSWOs. Brinker et al. (1995) and Brittan, et al. (2009) also propose migrating routes that indicate owls in eastern Indiana are likely to be arriving from eastern Great Lake regions.
MGBS has a good population of oak species, which produce ample food for Peromyscus spp., which are a favored prey for NSWOs (Brittan, et al., 2009). Given limited pine forest for sheltered habitat, it is reasonable to inquire as to the adaptability of NSWOs to utilize deciduous forest, with scattered pine forest, as wintering grounds.
Project Owlnet has an established protocol for mist-netting NSWOs (Brittan, et al., 2009). The banding station at MGBS has been following this protocol since its inception. The proposed project will assist in filling the void of data for NSWOs in Indiana as mentioned by Brittan, et al., (2009).
Using the Project Owlnet protocol for mist netting NSWOs (three nets in a north-south row, one net extending to the west and another extending to the east), owls will be lured using callers. Since mortality of hatch year birds has been shown to be high, transmitters will be attached to after-hatch-year female birds in order to monitor their migratory or residential habits in relation to MGBS.
Objective for the project:
- Where are NSWOs roosting at MGBS?
- Do NSWOs overwinter at MGBS?
- Does MGBS provide suitable overwintering habitat?
- How long do migrating NSWOs stop-over in east-central Indiana?
- Are migrating NSWOs demonstrating site fidelity when returning to their breeding grounds?
Findings will become a part of the Motus project.
Beckett, Sean R., & Proudfoot, Glenn A. (2011). Large-scale movement and migration of Northern Saw-whet Owls in eastern North America. The Wilson Journal of Ornithology: 123(3): 521-535.
Brinker, D.F., Duffy, K. E., Whalen, D. M. Watts, B.D., & Dodge, K.M. (1995). Autumn migration of Northern Saw-whet Owl (Aegolius acadicus) in the middle Atlantic and northeastern United States: What observations from 1995 suggest. Proceedings from the 2nd Owl Symposium. Accessed 9-25-2018: https://www.nrs.fs.fed.us/pubs/gtr/gtr_nc190/gtr_nc190_074.pdf
Brittan, R.A., Meretsky, V.J., Gwinn, J.A., Hammond, J.G., & Riegel, J.K. (2009). Northern Saw-whet Owl (Aegolius acadicus) autumn migration magnitude and demographics in south-central Indiana. Journal of Raptor Research: 43(3), 199-209.
Churchill, J.B., Wood, P.B., & Brinker, D.F. (2002). Diurnal roost site characteristics of Norther Saw-whet Owls wintering at Assateague Island, Maryland. Wilson Bulletin: 112(3), 332-336.
Churchill, J.B., Wood, P.B., & Brinker, D.F. (2002). Winter home range and habitat use of female Northern Saw-whet Owls on Assateague Island, Maryland. Wilson Bulletin: 114(3), 309-313.