COSEWIC assessment and status report on the Red Crossbill percna subspecies Loxia curvirostra percna in Canada
- Assessment Summary
- Executive Summary
- COSEWIC History, Mandate, Membership and Definitions
- Lists of Figures, Tables and Appendices
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Species
- Existing Protection or Other Status
- Summary of Status Report
- Technical Summary
- Acknowledgements and Literature Cited
- Biographical Summary of the Report Writers, Authorities Contacted, and Collections Examined
Crossbills are highly specialized holarctic finches that feed on the seeds of coniferous trees. Crossbills are often nomadic or irruptive over their ranges because the production of conifer seeds fluctuates markedly from year to year over continental scales (Bock and Lepthien 1976). Red Crossbills are distributed year-round throughout the boreal forests of North America and Eurasia, and southward to the coniferous forests of northern Spain, northern Africa, the Mediterranean islands, northern India, southern China, Japan, and the northern Philippines (Godfrey 1986).
Red Crossbills follow a boreal/coniferous distribution in North America. In the United States and Mexico, they generally breed in the boreal forests of Alaska, in the western coniferous forests south to California, Nevada, Arizona, Mexico, and Central America, in New England’s eastern coniferous forests, and in disjunct populations in the Appalachian mountains of western Virginia, eastern Tennessee, and western North Carolina (Adkisson 1996). Red Crossbills at times appear far beyond this range, particularly in the eastern United States, when birds wander large distances in response to northern food shortages.
The breeding range of Red Crossbills in Canada is variable. Nesting in a given location is no indication that nesting will occur in the same location the following year (Godfrey 1986). In general, Godfrey (1986) reports that Red Crossbills breed in the coniferous forests of southern Yukon, southwestern Northwest Territories, all of British Columbia (including coastal islands), Alberta (in the south confined to the western mountainous region), northwestern and central Saskatchewan, southern Manitoba, central and southern Ontario (except the extreme southwestern region), southern Quebec, New Brunswick (except possibly the northwestern region; Erskine 1992), Prince Edward Island, Nova Scotia, and Newfoundland (but are absent from Labrador; Todd 1963). The Canadian range of Red Crossbills is illustrated in Figure 3.
Range changes among Red Crossbills have been noted in the Maritimes and on the island of Newfoundland (see section on Newfoundland range, below). Red Crossbills occurred regularly in the Maritimes until the 20th century (Erskine 1992), but were virtually absent from Nova Scotia after 1922 (Tufts 1986), with no nests found after 1913 (Erskine 1992). This absence may be due to the history of logging Eastern White Pine (Pinus strobus) and Eastern Hemlock (Tsuga canadensis) in northeastern North America (Erskine 1992), which has been related to the decline of Red Crossbills in New England (Dickerman 1987). Breeding Red Crossbills returned to the Maritimes in the 1960s and 1970s, but remain uncommon, irregular residents showing no recent major irruptions (Erskine 1992). According to Tufts (1986) and more recent Christmas Bird Count data, numbers of Red Crossbills appear to be declining in the Maritimes.
Crosshatching represents known breeding range of L. c. percna, solid fill represents breeding range of other Canadian Red Crossbill subspecies. Range approximated from Godfrey (1986) and Létourneau (1996).
The percna subspecies is considered to breed only on the island of Newfoundland (Austin 1968). During periods of cone crop failures on insular Newfoundland, Godfrey (1986) suggested that the Newfoundland subspecies may wander to New Brunswick, Nova Scotia, Quebec and Ontario, perhaps escaping food shortages by moving to pine forests in eastern Canada and in the northeastern United States (Dickerman 1987). Large-billed Red Crossbills have been observed and collected in eastern Canada and New England (Griscom 1937; Peters and Burleigh 1951; Griscom and Snyder 1955; Austin 1968; Tufts 1986; McLaren 1991), though these were not considered to be breeding birds, and at least some may not be percna. For example, Dickerman (1986) discusses nine Red Crossbill specimens from New York State that are identified as pusilla, but he noted that while all of the specimens are large-billed, they are not as heavy-billed as specimens from Newfoundland. Large-billed specimens collected in Massachusetts have been identified as Red Crossbills, pusilla subspecies (Griscom and Snyder 1955). There are no reliable breeding records of Red Crossbills from Labrador (Todd 1963), where White-winged Crossbills are considered breeding residents (Benkman 1992b). Peters and Burleigh (1951) state that the Newfoundland race of Red Crossbill breeds in Nova Scotia, but do not substantiate this claim. A female Red Crossbill designated as pusilla was collected from Anticosti Island in 1963 (Ouellet 1969); its morphology is consistent with the percna subspecies (M. Gosselin, pers. comm., 2003). Red Crossbills (subspecies unknown) are seen on Saint-Pierre et Miquelon (Tuck and Borotra 1972), but there is no evidence that they breed there (R. Etcheberry, pers. comm., 2003).
Erskine (1992) suggests that one plausible explanation for the recent return of Red Crossbills to the Maritimes could be due to “overflow breeding” of the Newfoundland type. But, Benkman (1993c) argues that there is no evidence that percna survives on the mainland. He contends that the Newfoundland subspecies is adapted to foraging on the seeds of the Newfoundland Black Spruce (Picea mariana), which he argues, on the basis of very small and very geographically restricted samples, are thin-scaled due to the evolutionary absence of predation pressure from Red Squirrels (Tamiasciurus hudsonicus). He contends the percna subspecies cannot survive on mainland spruce which has evolved thicker scales in response to evolutionary pressure from squirrel predation. More recent work by Parchman and Benkman (2002), however, contradicts this previous line of reasoning and does not address whether the percna subspecies is restricted to Newfoundland conifers as a result of limitations that make mainland conifers un-exploitable by this subspecies. Most available information suggests that percna breeds only on insular Newfoundland, but this is not a definitive conclusion. In general, large-billed Red Crossbills tend to be more sedentary than small-billed ones (e.g. Marquiss and Rae 2002), which is a possible scenario in Newfoundland.
It is difficult to define the breeding range of Red Crossbills within Newfoundland, because they are no longer nesting where they were known to nest in the past. They have been observed in many different localities on the island, possibly due to locally irruptive behaviour. The last report of a Red Crossbill nest on insular Newfoundland was made in 1977 (WAM unpublished files, Table 2), and there are no recent reports of reproductive behaviour in Newfoundland.
Breeding bird surveys carried out by Memorial University of Newfoundland from 1980 – 1985 revealed that the highest incidences of Red Crossbills were observed in old growth forests in western Newfoundland. Red Crossbills were also detected on the northeast coast around Bonavista Bay and in the vicinity of Terra Nova National Park and on the Great Northern Peninsula (WAM unpublished data). More recently, Red Crossbills have been observed in a Red Pine (Pinus resinosa) stand near Gambo, central Newfoundland, and in and around St. John’s, on the Avalon Peninsula. It is not known whether their range has contracted in recent years, though their breeding range certainly seems to have (although survey effort has been very low). Presumably, the potential core breeding range corresponds to the coniferous forests of Newfoundland, but owing to nomadic wanderings they could occupy only parts of this range at any given time.
|2 juveniles||12 Dec 2002||B. Mactavish|
|some males singing||early Feb 1989||Cape Spear||B. Mactavish|
|immature male||3 Sept 1989||Cape Spear||R. Burrows|
|imm./female singing||27 Mar 1983||PortugalCove||WAM|
|2 fledglings||28 May 1983||B. Mactavish|
|immature||20 Apr 1980||LaManche||J. Piatt, WAM|
|2 fledglings||28 May 1980||B. Mactavish|
|nest with 3 eggs/chicks||3 - 31 May 1977||Torbay||R. Blacquiere|
|2 immatures||30 May 1975||LaManche||J. Piatt|
|nest with 3 2-3 d chicks||12 March 1971||Gander Bay||E. Baird|
|3 flying fledglings||21 May 1971||St. John’s||J. Wells|
|2 flying fledglings||23 May 1971||Salmonier Line||J. Wells|
|nest with 4 eggs, then chicks and fledglings||14 Jun - 14 Jul 1971||St. John’s||J. Landry|
|fledgling||13 May 1969||St. John’s||G. Greenlee|
|male specimen full breeding condition||21 Aug 1934||S of Grand Falls||(Rooke 1935)|
|continuous robust singing||26 Aug 1934||S of Grand Falls||(Rooke 1935)|
|2 juveniles||2 Sep 1934||S of Grand Falls||(Rooke 1935)|
|2 juvenile males||26-27 Jul 1912||Hobley Hills||(Noble 1919)|
It also must be pointed out that it is possible that some Red Crossbills seen in Newfoundland are not the percna subspecies, but other mainland subspecies. The information that is available on Red Crossbills sightings in Newfoundland generally does not provide sufficient information to discriminate between subspecies (for further information, see the subsection Field counts and typing of Red Crossbills in the section Population Sizes and Trends).
- Date Modified: