The Status and Distribution of the Prairie Warbler in Ontario
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99 The Status and Distribution ofthe Prairie Warbler in Ontario by Anne B. Lambert and Roy B.H. Smith The Prairie Warbler (Dendroica islands), where over one hundred discolor) has been considered a have been recorded. There are also relatively rare breeding species in three fall records from Newfoundland Ontario, but one whose exact In Ontario, the Prairie Warbler status was rather poorly known. was first recorded in 1900 (Samuel This led the Nongame Program of 1900; Ames 1901) and was first the Ontario Ministry of Natural proved to breed in the province in Resources to commission a study 1922 (Harrington 1922). Histor of its status in Canada, and early ically, breeding has been in 1984 a report was prepared confirmed in ten Counties/ (Lambert and Smith 1984). The Districts (Lambton, Haldimand Status Report detailed information Norfolk, Waterloo, Dufferin, available up to 1983, based on the Bruce, Simcoe, Muskoka, Parry literature and communications Sound, Peterborough, Frontenac) with knowledgeable birders, while and suspected in six more this paper summarizes those data. (Middlesex, Manitoulin, Hastings, Additional information obtained Prince Edward, Leeds and during the 1984 season has also Grenville, Lanark). Presently, been included, when available. however, breeding occurs on a regular basis in only six Counties Overview or Districts (Lambton, Simcoe, In Canada, the Prairie Warbler Muskoka, Parry Sound, Peterbor has been reported in five provinces ough, and Frontenac). The main but has been proved to breed only stronghold ofthe Ontario in Ontario. It is a very rare spring population is concentrated along migrant in Quebec (7 or 8 the eastern shore of Georgian Bay records), and a rare but regular fall in the Districts ofMuskoka and migrant in New Brunswick and Parry Sound, with smaller Nova Scotia (mainly on offshore numbers in Frontenac and Anne B. Lambert and Roy B.H. Smith, Box 222, Port Rowan, Ontario NOE IMO VOLUME 2 NUMBER 3 100 : Georgian Bay breeding range • other regular breeding sites (current) • isolated breeding record • possible breeding sites o former breeding sites Figure 1. Breeding distribution of the Prairie Warbler in Ontario: 1900-1984. Peterborough (Fig. 1). In these is typically dominated by mature areas the population appears to be but stunted white pine (Pinus stablef although a slight increase strobus), white and red oak may have occurred in Frontenac. (Quercus alba, Q. rubra), and by However, in Simcoe and Lambton patches ofcommon juniper Counties substantial declines have (Juniperus communis var. depres been documented. sa). Prairie Warblers most frequently select these low junipers Breeding Habitats for nest sites (Lord 1955; D.A. At least three distinct habitat types Sutherland, pers. comm.). Recent have been occupied in Ontario, all ly, use of a similar habitat along characterized by open, scrubby some hydro line rights-of-way in vegetation and usually zeric Frontenac Co. has also been conditions. The most important reported (RD. Weir, pers. habitat is the pine-oak-juniper comm.). scrub found along the Georgian The second important Ontario Bay shoreline and at scattered ~abitat is a sand dune habitat locations along the southern edge exemplified by the Lake Huron ofthe Canadian Shield (e.g. in dunes at Pinery Provo Park Peterborough and Frontenac (Lambton Co.) and, formerly, at Counties). This open,- rocky Wasaga Beach (Simcoe Co.), once habitat (often only 50% vegetated) the site of a large'colony'. At the ONTARIO BIRDS DECEMBER 1984 101 Pinery, the 'interdunal meadows' were first recorded at Port Franks frequented by Prairie Warblers in 1915, and during the 1930s at comprise a fairly open habitat with least 26 singing males were noted "scattered mature black oak; low over an 8 km length ofdunes shrubs ofjuniper, fragrant sumac, (Saunders 1934, in litt.). At this wild grape, choke cherry and red density there could have been 50 cedar~alllow, vegetation with pairs or more in the entire area of clumping evident" (T. Crabe, pers. habitat between Ipperwash and comm.). A detailed description of Grand Bend. Indeed, after the this habitat has been provided by Royal Ontario Museum's collect Sparling (1965). ing trip to the area in 1935, Snyder In the Turkey Point/St. was said to have described the Williams area (Haldimand-Norfolk Prairie Warblers there as RM.), sandy plains with planted "positively abundant" (J.L. Baillie pines and!or deciduous scrub notes, ex ROM files). However, comprise a third habitat type. cottage development has probably This open, successional habitat contributed to a decline in the typically includes pin cherry population since the 1930s, and (Prunus pensylvanica), sapling within Pinery Provo Park the oaks (Quercus spp.) and other planting of pines on some deciduous species. The plantations secondary and tertiaiy dunes only remain suitable as nesting during the 1950s may have led to habitat for 10 to 20 years (A. some reduction in habitat (J.D. Wormington, pers. comm.), but McCauley, pers. comm.). In recent sequential plantings by the years, increasing visitor pressures Provincial Forestry Station have could also have had some effect provided a virtually continuous (T. Crabe, pers. comm.). supply of habitat since the early In 1969 the population was 1930s. Second growth deciduous estimated at 17-22 males (J. scrub is used much more LameY,fide T. Crabe, pers. frequently within the Prairie comm.), but since then there Warbler's United States range, the appears to have been a slow only other Ontario examples being decline. Figures for some a single case of breeding in intervening years are not available, Waterloo RM. in 1982 and one of but from 1977 onwards the possible breeding in Middlesex numbers of singing males were Co. in 1983. An instance of estimated as follows: 1977 - 10 to possible breeding has also been 20; 1978 - 11 +; 1979 - 7?; 1980 recorded in old fields regenerating between 4 and 8, probably 6; 1981 to red cedar (Juniperus vir - between 6 and 8, probably 8; giniana) in Prince Edward Co. in 1982 - 5+; and 1983 - 5 (T. 1979. Crabe, pers. comm.; J.D. McCauley, pers. comm.). The Detailed Bre~ding Distribution present Pinery population seems to be stable at between 5 and 8 Lambton County. Prairie Warblers singing males, and the total VOLUME 2 NUMBER 3 102 population for the entire area that suitable habitat was between Grand Bend and Kettle disappearing (Goodwin and Point has been estimated at 10 Rosche 1971). Although complete pairs (T. Crabe, pers. comm.). counts or censuses were not conducted, the numbers involved Middlesex County. The Prairie were probably quite small. The Warbler has never been proved to highest recorded count of eight breed in Middlesex, but two singing males was made in 1972 summer records in the London (A. Wormington, pers. comm.), area in 1930 and 1931 raised the and the slow decline since that possibility that breeding might time can be attributed to the have occurred (Saunders and Dale increasing maturity of the pine 1933). More recently, a singing plantations. The last year in which male was observed in the'Skunk's singing males (2 or 3) were Misery' area, Mosa Twp. on 1, 4 recorded was 1979 (R.J. Curry, and 14 July 1983, again suggesting pers. comm.; C.J. Risley, pers. the possibility of breeding. This comm.), but in 1984 a pair and an bird was occupying a successional additional singing male were habitat described as a mixture of located by the authors at a site low pines, birch and aspen, near Turkey Point. Although interspersed with clearings (S. breeding was not confirmed, this Connop, pers. comm.). find suggests that the Prairie Warbler may yet persist as a Haldimand-Norfolk Regional breeding species in Haldimand Municipality. Published and Norfolk R.M. unpublished records indicate that in the early 1930s a small breeding Waterloo Regional Municipality. population was discovered in the There is a single, unprecedented Turkey Point-St. Williams area, in breeding record from 1982, when a pine plantations established by the nest with eggs was found near St. Williams Forestry Station. In Bamberg, Wilmot Twp. by R. 1936 a 'colony' of six males was Pickering (P.F.J. Eagles, pers. reported at Turkey Point by G.W. comm.). The habitat was described North (Toronto Ornithological as "second growth forest with Club records,per ROM files) and nesting Golden-winged Warblers breeding was confirmed on 15 July as well". 1942, when a nest with three young was found in South Walsingham (now Norfolk) Twp. Dufferin County. The single (F. North 1943, in. litt.). A small record concerns a nest with 5 eggs population persisted in the St. found on 11 June 1927 on Williams Forestry Station through Shrigley Creek, Melancthon Twp. the next few decades as phased by Dr. P. Harrington (Ontario plantings kept a supply of suitable Nest Record Scheme - hereafter habitat available for about 50 ONRS). The nest was located in years, but by 1971 it was noted juniper, but it is not known ONTARIO BIRDS DECEMBER 1984 103 whether appropriate habitat exists comm.) indicates that he located a in this area today. 'colony' of about 8 pairs in St. Edmunds Twp. in 1952. In 1953 Bruce County. Observations of he found a nest with young, but singing males suggest that breeding there were fewer breeding pairs, may have occurred at the following and in the following years the locations: near Cameron Lake, St. colony continued to decline, fInally Edmunds Twp. in 1905 (Saunders disappearing after 1958. 1906); at Colpoy's Bay, More recently, the late George Albemarle Twp. in 1908 and 1909 North is reported to have seen (Klugh 1909,1910); at McVicar, Prairie Warblers at Miller Lake St. Edmunds Twp. in 1928, 1930 Lindsay Twp. in the 1950s and' and 1934, at Stokes Bay, Eastnor 1960s (J.