Red-shouldered Hawk and Spring Woodpecker Survey 2003 Final Report Produced For Ontario Ministry of Natural Resources – Wildlife Assessment Program January 2004 Debbie S. Badzinski Bird Studies Canada / Études D’Oiseaux Canada P.O. Box/B.P. 160, 115 Front St., Port Rowan, ON Canada N0E 1M0 www.bsc-eoc.org Page 1 of 25 EXECUTIVE SUMMARY The Red-shouldered Hawk (Buteo lineatus) is a rare to locally uncommon breeding bird in Ontario (Austen and Cadman 1994, Austen et al. 1994, James 1991, Sutherland 1994), and is classified as a species of Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and Vulnerable in Ontario by the Ontario Ministry of Natural Resources (OMNR). The Red-shouldered Hawk survey began in 1990, with the primary goal of assessing whether forest management practices were negatively affecting Red-shouldered Hawks in Ontario. Surveyors also gather data on other raptor species and five species of woodpeckers. In 2003, 53 volunteers completed 55 Red-shouldered Hawk and Spring Woodpecker survey routes throughout central Ontario. Surveyors recorded 167 Red-shouldered Hawks on 67% of the routes, for a mean of 3.04 birds/route. This is the second lowest number of Red-shouldered Hawks recorded since the survey began. Turkey Vulture was the second most common raptor species recorded by volunteers (mean: 1.38 birds/route), followed by Broad-winged Hawk (mean: 1.07 birds/route) and Red-tailed Hawk (mean: 0.22 birds/route). Average numbers of each raptor species have shown little change between 1991 and 2003. Despite the observed decline in number of Red-shouldered Hawks detected during the 2003 survey, numbers have been stable with only minor annual fluctuations from 1991-2003. This suggests that although the population remains small and is considerably lower than it was historically, there is sufficient habitat in central Ontario to maintain the present Red-shouldered Hawk population. However, the continued expansion of urban areas and ever-increasing cottage development in prime Red-shouldered Hawk breeding habitat are ongoing threats to the Ontario population. 2003 Red-shouldered Hawk and Spring Woodpecker Survey Page 2 of 25 TABLE OF CONTENTS EXECUTIVE SUMMARY.........................................................................................................1 INTRODUCTION ......................................................................................................................3 METHODS.................................................................................................................................4 Broadcast equipment...................................................................................................................6 Route selection ...........................................................................................................................6 DATABASE STRUCTURE .......................................................................................................7 DATA ANALYSIS.....................................................................................................................8 RESULTS...................................................................................................................................9 Volunteer participation ...............................................................................................................9 Survey conditions .......................................................................................................................9 Survey results .............................................................................................................................9 Red-shouldered Hawks ...............................................................................................................9 Other raptors.............................................................................................................................13 Woodpeckers............................................................................................................................13 Woodpecker trends from Breeding Bird Survey ........................................................................19 DISCUSSION...........................................................................................................................19 Red-shouldered Hawk population changes................................................................................19 Woodpecker population changes...............................................................................................20 ACKNOWLEDGMENTS.........................................................................................................20 LITERATURE CITED .............................................................................................................21 2003 Red-shouldered Hawk and Spring Woodpecker Survey Page 3 of 25 INTRODUCTION The Red-shouldered Hawk (Buteo lineatus) was once the most common hawk in southern Ontario, but it has experienced a dramatic, continent-wide decline in the last century (Crocoll 1994). The Red-shouldered Hawk is now a rare to locally uncommon breeding bird in Ontario (Austen and Cadman 1994, Austen et al. 1994, James 1991, Sutherland 1994), and is classified as a species of Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and Vulnerable in Ontario by the Ontario Ministry of Natural Resources (OMNR). These designations are largely based on the decline in the southern Ontario breeding population that has occurred in the last century (Risley 1982, Austen and Cadman 1994). Ninety percent of Ontario breeding records for Red-shouldered Hawks are from the Great Lakes Forest Region, and a few additional breeding sites have been identified in the Carolinian and Southern Boreal forests. Ontario constitutes approximately 5% of the Red-shouldered Hawk’s total North American breeding range (Austen and Cadman 1994). Red-shouldered Hawks occur in a broad array of North American forest types, but they prefer large tracts of mature to old growth, mixed forests, especially bottomland hardwood riparian areas and flooded deciduous swamps (Crocoll 1994). This species also requires closed canopy forests for successful reproduction, and is sensitive to changes in forest structure following timber harvesting (Crocoll 1994). Conversely, reduced canopy closure as a result of logging practices may benefit Red-tailed Hawks (Buteo jamaicensis), which may then displace or out- compete Red-shouldered Hawks (Bryant 1986). The dependence of Red-shouldered Hawks on large, mature forests raised the concern that timber management practices may be negatively affecting the hawks. As a result, the Red-shouldered Hawk and Spring Woodpecker Survey was initiated in 1990. The primary objectives of the survey are to provide statistically reliable population trend data for Red-shouldered Hawks, Pileated Woodpeckers, and Yellow-bellied Sapsuckers and determine whether forest management practices are negatively affecting these species. The study area is restricted to deciduous or mixed forest habitat in central Ontario, the core breeding range of the Red-shouldered Hawk. Woodpeckers in general, and more specifically the Pileated Woodpecker and Yellow-bellied Sapsucker, may also be influenced by forest management practices in Ontario, because these species rely on large, relatively mature forests and depend on snags for breeding. Pileated Woodpeckers and Yellow-bellied Sapsuckers are easier to detect in late April and early May (the current survey window for Red-shouldered Hawks) than in June when other breeding bird surveys are conducted (Peterjohn et al. 1994). Furthermore, because of their secretive habits during June, these species are not adequately monitored by other bird surveys, such as the Breeding Bird Survey (McLaren 1993). For this reason, participants in the Red-shouldered Hawk survey also collect data on woodpeckers. The Red-shouldered Hawk and Spring Woodpecker Survey is run by Bird Studies Canada, as 2003 Red-shouldered Hawk and Spring Woodpecker Survey Page 4 of 25 part of the Ontario Birds At Risk (OBAR) program, in cooperation with the Wildlife Assessment Program of the Ontario Ministry of Natural Resources. This report summarizes results of the 2003 survey. Annual indices were calculated for numbers of Red-shouldered Hawks from 1991– 2003, and for the five most frequently encountered woodpecker species for the period 1992– 2003 (1996-2003 for non-target species). METHODS The Red-shouldered Hawk and Spring Woodpecker Survey is a roadside survey that uses playback calls to elicit responses from Red-shouldered Hawks. Observations of other raptor and woodpecker species are recorded by passive listening or visual observations. The survey methods were proposed by Szuba (1990), and were further tested and modified by Callaghan (1990) and Austen (1991). Survey routes are located along secondary roads passing through as much deciduous woodland as possible. Each survey route is 19 km long and consists of 20 stations spaced 1 km apart. All routes are surveyed once annually within the time period of 17 April- 7 May. This survey window was selected to correspond with the pre-incubation period for Red-shouldered Hawks in Ontario, during which the highest response rate to playback is expected. Prior to the survey, each surveyor is provided with a participant's kit containing: a 1:50,000 scale topographic map of their survey route; stop descriptions of their