Ohio Bird Banding Association

Taking Advantage of Technology:

In Its 15th Year The Cincinnati Red Shouldered Hawk Project Adds Video Monitoring!  by Sara Johnson Miller


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   NEW!  Video of chicks in the Nest         YouTube channel - Cincinnati Red-shouldered Hawks

As many of you are aware, the Red-shouldered Hawk (RSHA) population around Cincinnati, Ohio is the first-documented suburban-adapted population of the eastern subspecies, and has been studied annually since 1997 by Dr. Cheryl Dykstra, Jeff Hays, Melinda Simon, and a small group of other important volunteers. This year during the Spring breeding season, the RSHA Team added a graduate student to their ranks, Sara J. Miller, to incorporate a new aspect to their research. Sara is attending Arkansas State University and pursuing her Master’s degree under the advisement of Dr. James (Jim) C. Bednarz, whose lab specializes in using video monitoring to study nesting ecology of various avian species. Their goal is to use video time-lapse cameras at these suburban RSHA nests to further investigate the breeding ecology of this population to help understand more about how they are adapting to human encroachment and urbanization.

The team visited previously-known territories and determined whether they were occupied (e.g., hawk present, nests with fresh sticks or green vegetation lining) – over 250 territories were visited, due to the accumulation of territories over the 14-year period since the project began! They monitored nests from February - June (pre-laying until fledging). At selected nests, they installed 24 h/day digital infra-red video cameras. Cheryl & Jeff did the climbing, while Sara and Melinda provided ground support & processed chicks. Video was recorded with micro-DVRs and the system was powered by a deep-cycle marine battery, and Sara replaced memory cards and batteries on a 3-day cycle.
      

At 5 nests, they installed cameras at occupied nests prior to egg-laying. At 6 nests, they installed cameras after eggs hatched, when the nestlings were estimated to be 3-12 days old. The cameras remained in place until the nest failed or fledged young. Within the first week of hatching, they marked the nestlings on their heads and backs with Sprayolo non-toxic liquid livestock dye to facilitate differentiation of nestlings in the video. They also climbed again to band (USGS & colored number-letter bands) the nestlings and to re-paint their heads after initial paint began to fade.

Sara is currently (and indefinitely) working on extracting data from the 14,800+ hours of video that were recorded. Data extracted during video review will include adult behavior during clutch initiation, time elapsed between a researcher’s climbing event and when a parent RSHA returned to the nest, causes of nest failure, nestling behavior and aggression rates, prey delivery rates and prey types. In addition to the 11 camera nests, the team also monitored the 112 territories that became occupied until nests failed or
 fledged young.
Preliminary Results & Discussion:
Of the 5 nests that received a camera prior to egg-laying, all pairs laid eggs, and 3 of these pairs fledged young, while the remaining 2 nests failed due to predation or nest disturbance. These results show that mounting the cameras during the courtship phase, after the adults occupied the nest, did not seem to disturb the birds. This method also provided more accurate and complete data for an entire nesting period than mounting cameras post-hatching.
 
Of the 6 nests that received and retained a camera post-hatch, all fledged young. However, after installing one camera post-hatch, Jeff discovered that the female parent was avoiding the nest, although the male had no qualms about delivering piles of prey. Fortunately, this unusual case was caught within 24-hours of camera installation, and allowed the team to act quickly to remove the disturbing camera and allow behaviors to return to normal. The team is happy to report that this nest successfully fledged all three of its nestlings! We also learned a valuable lesson about individual birds’ tolerance levels for nest disturbance. It also furthers the argument for installing cameras prior to egg-laying, because it minimizes consequences of disturbing the breeding pair.

 
There is good evidence to support the idea that RSHAs have partial incubation, and Sara will analyze this to determine the point at which the adults begin full incubation during clutch initiation.  Thus far, the data indicates that most sibling aggression events occurred within the first week after hatching, which suggests that the dominance hierarchy is established during this time and may influence the probability of success of each nestling through the remainder of the nestling period, and perhaps even after fledging.
 
Prey types delivered to nests was similar to that described previously by the team (from conducting direct observation of nests) and included small mammals, frogs and other amphibians, snakes, and invertebrates. This indicates that this population of suburban RSHAs are indeed generalist predators, similar to populations nesting in more typical, remote forested habitats.

Causes of nest failure or chick mortality were depredation by a Great-horned Owl and a raccoon, and a very suspenseful three-week battle between a pair of nesting RSHAs and an Eastern gray squirrel, which the squirrel ultimately won. Again, the team is happy to report that the pair re-nested in a new location and successfully fledged two chicks, albeit also in the company of several squirrels!

Future Plans:
Sara will be returning to Cincinnati in February of 2012 to join the RSHA Team for the second season of her Master’s project, and then they plan to get ALL cameras (12?) installed during the courtship phase! Other analyses will include mapping the locations of all of the recapture/recovery locations of banded birds from 1997 to 2012 with the hopes of gleaning information about the relationship between hatch order and dispersal distances from natal territories. More mapping analyses will be conducted to quantify landcover types surrounding the nesting areas and to look for relationships between landcover and prey deliveries. The team continues to enjoy the benefits of “citizen science” with reports of banded birds being sighted or recovered year-round.

The video monitoring project would not be possible without the support of The RSHA Team: Cheryl Dykstra, Melinda Simon, Jeff Hays, and their incredibly supportive families, RAPTOR Inc., Hawk Mountain Sanctuary, The Audubon Society of Ohio, Arkansas Audubon Society Trust, Arkansas State University, and all of the fantastic, cooperative landowners in Cincinnati!  

 
The Ohio Bird Banding Association. All rights reserved. 2011