Assessment of the Avifauna of the Red Hill Valley Hamilton Naturalists' Club Colin Macdonald March 1996 Macdonald Biological Inventory of Red Hill Valley Avifauna Acknowledgments Since this report required me to review all available material on the avifauna of the Red Hill Valley, as well as locate suitable external sources of comparative data, I was necessarily dependent upon many people for information and advice. This report could never have gotten off the ground without the help of many concerned and dedicated southern Ontario naturalists that I had the pleasure of dealing with over the course of this project. Firstly, I would like to thank Don McLean, the project manager, for doing a wonderful job of providing me with the information I needed where he had it, or contacts for those who did. Ken Symington and Paul Rose were also helpful in providing additional insights on their source material. Anthony Goodban, the inventory’s botanist, went out of his way to help me, providing air photos and information to aid me in visualizing the valley during the warm months of the year in which the source studies were actually carried out. Thanks also go to John McCracken and Mary Gartshore at the Long Point Bird Observatory, and Brian Pomfret at the Royal Botanical Gardens for providing me with insights and information to guide me in tackling the complexity and challenge of analyzing avian migration in Ontario. Madeline Austen also went out of her way to further my understanding of southern Ontario’s avian communities, and she put me on to Steve Hounsell at Ontario Hydro who provided the GIS forest cover maps that greatly enrich this report. Finally, I would like to thank the reviewers: Bruce Duncan, Bob Curry and especially Rob Dobos who all provided me with very detailed and useful critiques to improve my understanding and expression of avian ecology. 122 Hamilton Naturalists’ Club March 1996 Macdonald Biological Inventory of Red Hill Valley Avifauna Introduction features. The valley has long been known to local naturalists and members of the Hamilton Naturalist's The 1995 biological inventory of the Red Hill Valley Club (HNC) have been recording their birding included three separate avifaunal studies and a wealth of observations from the area for decades. supplementary data. Extensive migratory surveys were conducted in the spring by Paul Rose and in the fall by Previous Avifaunal Studies in Red Hill Valley Ken Symington, with the assistance of numerous The first systematic attempt to enumerate the breeding volunteers. A breeding bird survey was also carried out birds of the valley was undertaken by Wormington by Michael Patrikeev. His data was supplemented by (1976) in conjunction with the original ESA studies. Rose’s observations during the spring migratory survey Since then the area was examined during the Ontario as well as breeding information gathered by William Breeding Bird Atlas (OBBA) program (Cadman 1987) Lamond during his 1995 inventory work on and again by Wormington and others in 1990 and 1991 herpetofauna and butterflies. In addition, Lois Evans in conjunction with the NAI. In addition during the late culled historical data from the Noteworthy Bird Records 1980s participants in the Ontario Rare Bird Breeding of the Hamilton Naturalists’ Club for the period from Program (ORBBP) took interest in the Van Wagner's 1947 to 1994. Kevin McLaughlin provided Christmas Marsh because of the threatened Black Tern colony bird count data for the period from 1974 to 1995. there. Dobos (1989) has summarized the biological Evans’ report is published in this volume. Portions of significance of this small but productive Class 1 the reports from Rose, Patrikeev and Symington are wetland, citing its importance not only to the Black Tern included as Appendix C at the end of this report. This but to other significant species such as the Least Bittern wealth of material forms the basis of this assessment of and Common Moorhen. the avifaunal features of the Red Hill Valley. The 1995 field studies carried out by Patrikeev, Rose The Study Area and Symington comprised over 700 hours of field work. The boundaries of the study area covered in this report The various components of the breeding bird study are described in the major source papers (Patrikeev were carried out between 8 April and 10 July. The 1995, Rose 1995 and Symington 1996) and are spring migratory study period covered the months of generally coincident with two Environmentally Sensitive April and May while the fall migration field work was Areas designated in the Official Plan of the Regional done between 14 August and 31 October. Municipality of Hamilton-Wentworth. These are the Redhill Creek - King's Forest (ESA 23) and Redhill Creek Marsh - Van Wagner's Marsh (ESA 28). Background These areas make up a total of approximately 683 ha Many forest bird species are experiencing significant covering over 9 km of the Redhill Creek watershed population declines. Several recent papers (Terborgh from the southern end of the Mount Albion 1992, Herkert et al 1993, Askins 1995) have Conservation Area above the escarpment to Van summarized the nature of these declines and the reasons Wagner's Ponds near Lake Ontario, just upstream of behind them. where the creek empties into Windermere Basin. Detailed descriptions of the location, geology, Forest fragmentation has been identified as particularly hydrology, flora and fauna of these areas as well as detrimental to forest interior songbirds because it discussion of their regional significance and linkages to increases the ratio of forest edge to forest interior, other natural areas can be found in the recently reducing the percentage of forest that is free from edge completed Hamilton-Wentworth Natural Areas effects. The many small woodlots that dot eastern Inventory (NAI) under site summaries HAMI-69 and North America, though they appear healthy, are HAMI-61 (Heagy 1993). essentially all edge and consequently are very hostile to many neotropical migrants. Surrounded by extensive and continuing urbanization, the Red Hill Valley stands out as a ribbon of natural and It is not the edges that are the problem, but the semi-natural space in the east end of Hamilton, Ontario increases in nest predators and parasites associated with exhibiting a good variety of physical and biological them. The residential developments and farmlands that March 1996 Hamilton Naturalists’ Club 123 Macdonald Biological Inventory of Red Hill Valley Avifauna have replaced the forests, sustain high populations of Many migratory species breed and overwinter in nest predators such as raccoons and feral cats, as well ecologically similar habitat (Welty and Baptista 1988) as Blue Jays and American Crows which are maintained suggesting that these species have specialized or adapted year round with waste grain, garbage, and suburban their foraging and other behaviours to a certain habitat bird feeders. The Brown-headed Cowbird, type. The degree of habitat specialization seems graminivorous and gregarious and North America's especially high in species of the forest interior. These leading nest parasite, has also thrived under these birds simply may not have the plasticity to switch to conditions, expanding dramatically in numbers and other habitat types, and it is reasonable to surmise that range over this century. this limitation may also apply during migration. However, there is some evidence that migrants can be Edge enhanced nest predation extends more than 100 fairly flexible in stopover habitat selection and do not metres into a forest, and female cowbirds have been necessarily require the same large pristine habitat tracts known to venture much further than that in search of on migration as they find necessary for breeding host nests. Although the minimum forest size necessary (Winker et al 1989). to support neotropical forest dwelling birds depends to some extent on local variables, results of several studies Concern over the fragmenting effects of present and in Eastern North American deciduous forests suggest planned future development in the Red Hill Valley have that 150 ha of contiguous forest may be the bare partly provided the impetus for this study. minimum needed to attract some area-sensitive forest Unfortunately, the valley is a textbook case of forest interior birds like the Cerulean Warbler. fragmentation, with a high degree of patchiness reflecting various past and present land-use management The mere presence of a species during the breeding plans. season, however, does not ensure its breeding status. Aside from heavy nest predation and nest parasitism The original Carolinian forest was cleared for farming in rates, forest-interior species in small woodlots may be the last century and the second growth which has been suffering reduced reproductive success simply because allowed to return is broken up by conifer plantations, they are going unmated. Several studies indicate that golf courses, playing fields, old landfills, quarries and density and pairing success in the Ovenbird is positively cut areas. At present, it is also dissected by many paths correlated with forest fragment size and regional forest and trails as well as several arterial roads, sewage mains cover (Gibbs and Faaborg 1990, Villard et al 1993, and two rail lines. Only the King's Forest Park area Robinson 1992). This trend is best explained through contains a patch of forest large enough to contain any sexual selection by females that avoid low quality males interior. found in marginal habitat. Purpose The significance of habitat fragmentation to migrating The purpose of this study is to describe the use of the birds is not as well studied, but some logical inferences valley by breeding and migratory birds, to assess its can be made based on what is known about their significance in the greater region, and to make foraging ecologies and their physiology during recommendations for the management of the area with migration.