COSEWIC Assessment and Status Report on the Lewis's Woodpecker in Canada 2001

  1. Table of Contents
  2. COSEWIC Assessment Summary
  3. COSEWIC Executive Summary from the 1999 Status Report
  4. Species Information
  5. Protection
  6. Population Sizes and Trends
  7. Habitat
  8. General Biology
  9. Limiting Factors
  10. Special Significance of the Species
  11. Evaluation and Proposed Status
  12. Technical Summary
  13. Acknowledgements
  14. Literature Cited
  15. Biographical Summary of the Author(S)


COSEWIC status reports are working documents used in assigning the status of wildlife species suspected of being at risk. This report may be cited as follows:

Please note: Persons wishing to cite data in the report should refer to the report (and cite the author(s)); persons wishing to cite the COSEWIC status will refer to the assessment (and cite COSEWIC). A production note will be provided if additional information on the status report history is required.

COSEWIC 2001. COSEWIC assessment and status report on the Lewis’s woodpecker Melanerpes lewis in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 18 pp.

(http://www.registrelep-sararegistry.gc.ca/sar/assessment/status_e.cfm)

Velland, M. and V. Connolly. 1999. COSEWIC status report on the Lewis’s woodpecker Melanepes lewis in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-18 pp.

Please note the status recommended in the Section "Evaluation and Recommended Status" of the report may differ from the latest status assigned to the species by COSEWIC.

Également disponible en français sous le titre Évaluation et Rapport de situation du COSEPAC sur la situation du pic de Lewis (Melanerpes lewis) au Canada.

Cover illustration:

Lewis’s Woodpecker --J. Crosby, The Birds of Canada, by W. Earl Godfrey, Canadian Museu of Nature, Ottawa, ON.

©Minister of Public Works and Government Services Canada 2003

Catalogue No. CW69-14-405-2004E-PDF

ISBN 0-662-38278-1

HTML: CW69-14/405-2004E-HTML

0-662-38279-X

COSEWIC Assessment Summary

Common name : Lewis’s Woodpecker

Scientific name :Melanerpes lewis

Status : Special Concern

Reason for designation : Population is relatively small and part of the Canadian range has been lost. Required breeding habitat – large trees in open habitats – is under pressure from urban and agricultural developments.

Occurrence : British Columbia

Status history : Designated Special Concern in April 1999. Status reexamined and confirmed in November 2001. Last assessment based on an existing status report.

COSEWIC Executive Summary from the 1999 Status Report
Description

Lewis’s Woodpecker (Melanerpes lewis) is a medium-sized (26-28 cm) woodpecker with a greenish black head, back, wings, and tail, and a distinctive pinkish red belly. It has a dark red face patch and prominent silvery gray collar and upper breast. The plumage coloration of Lewis’s Woodpecker distinguishes it from other woodpeckers. Sexes are similarly colored with males usually slightly larger than females. Juveniles are distinct from adults, being overall black and more brownish-black dorsally, generally lacking the extensive gray, red, and pink coloration of adults. In both adults and juveniles, the legs and feet are gray, the bill is black, and the iris is dark.

Distribution

Lewis’s Woodpecker occurs only in western North America, where it breeds from British Columbia in the north, south to California and Arizona, and east to Colorado. Throughout its range its distribution is sparse, with populations concentrated in dispersed areas of suitable habitat. Large dead or dying trees are required for nesting, and open areas with abundant insects are preferred feeding areas. Breeding birds in Canada migrate south for the winter, except for a small number in the Okanagan Valley.

Population size and trends

While there are no estimates of the global population size for the species, there are probably at least 600 breeding pairs in British Columbia each year. Over the past century, both the global and Canadian populations have declined, primarily due to a loss of suitable habitat. Breeding populations on Vancouver Island and in the lower Fraser River Valley were extirpated in the 1960’s.

Habitat

The most common breeding habitats of Lewis’s Woodpecker are open, mature ponderosa pine forests, and riparian black cottonwoods stands. Essential habitat features are old trees that have decayed or died (for breeding), and open areas (for feeding). Suitable breeding habitat in Canada is restricted to lower mountain slopes and valley bottoms in southern interior British Columbia.

General biology

Lewis’s Woodpeckers tend to form long-term or permanent mating pairs, and return to the same nesting sites year after year. Compared to most woodpeckers, the species has a large clutch size, at 5-9 eggs. Lewis’s Woodpeckers generally breed as solitary pairs, but the species is also known to nest in loose colonies in some regions As an opportunistic feeder, Lewis’s Woodpecker feeds on a wide variety of insects, fruits and nuts depending on local availability. In remote areas, the birds tend to be shy and quite sensitive to human activity, whereas in urban or suburban areas, individuals may become quite habituated to human activity. One pair even nested in a power pole in a Penticton parking lot!

Limiting factors

Widespread clearing of ponderosa pine forests is likely responsible for much of the population decline in this century. Increasing human development in British Columbia continues to result in the loss of critical habitat for the species. Fire suppression in ponderosa pine forests is common practice in British Columbia, and results in the development of dense stands which are entirely unsuitable for Lewis’s Woodpecker. Management of these forests will be pivotal in deciding the future fate of Lewis’s Woodpecker in Canada.

Protection

Lewis’s Woodpecker is physically protected under the Migratory Birds Convention Act of 1994 in the U.S.A. and Canada, and under the British Columbia Wildlife Act of 1982 in British Columbia. However, the future health of the Canadian population depends greatly on protecting its habitat as well. Although recent forest practice guidelines in British Columbia have acknowledged the need to conserve Lewis’s Woodpecker habitat, these are not actually resulting in the preservation of many nesting sites.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) determines the national status of wild species, subspecies, varieties, and nationally significant populations that are considered to be at risk in Canada. Designations are made on all native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fish, lepidopterans, molluscs, vascular plants, lichens, and mosses.

COSEWIC comprises representatives from each provincial and territorial government wildlife agency, four federal agencies (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership), three nonjurisdictional members and the co-chairs of the species specialist groups. The committee meets to consider status reports on candidate species.

Species : Any indigenous species, subspecies, variety, or geographically defined population of wild fauna and flora.

Extinct (X) : A species that no longer exists.

Extirpated (XT) : A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E) : A species facing imminent extirpation or extinction.

Threatened (T) : A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC)* : A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

Not at Risk (NAR)* : A species that has been evaluated and found to be not at risk.

Data Deficient (DD)*** : A species for which there is insufficient scientific information to support status designation.

* : Formerly described as “Vulnerable” from 1990 to 1999, or “Rare” prior to 1990.

** : Formerly described as “Not In Any Category”, or “No Designation Required.”

*** : Formerly described as “Indeterminate” from 1994 to 1999 or “ISIBD” (insufficient scientific information on which to base a designation) prior to 1994.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list.

Environment Canada Environnement Canada

Canadian Wildlife Service Service canadien de la faune

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

Species Information
Distribution
America’s
Breeding

Lewis’s Woodpecker occurs only in western North America, where its breeding distribution is generally coincident with that of ponderosa pine (Pinus ponderosa). It currently breeds from southern British Columbia in the north, south to California, central Arizona and southern New Mexico, and east to eastern Colorado (Tobalske 1997; see Figure 1). Throughout its range, the distribution of Lewis’s Woodpecker is generally sparse, with local concentrations in areas of suitable habitat (Siddle and Davidson 1991; Tobalske 1997). As well, there is often considerable year-to-year variation in abundance at individual localities, where the species may sometimes disappear completely and reappear years later (Bock 1970). The former distribution of Lewis’s Woodpecker includes parts of coastal British Columbia (Cooper et al., 1998), northwestern Oregon (Gilligan et al., 1994), and southern California (Small 1994), areas where the species no longer breeds.

Wintering

The winter range of Lewis’s Woodpecker is essentially the same as the year-round range and extends from southwestern Oregon, centraul Utal and central Colorado in the north, south occasionally to northern Mexico (Tobalske 1997; see Figure 1). A small number of birds spend the winter as far north as British Columbia each year (Cooper et al., 1998).

Canada
Breeding

In Canada, the breeding range of Lewis’s Woodpecker is essentially restricted to British Columbia. The species occurs occasionally in the foothills and lower mountain slopes of western Alberta (S. Brechtel, pers. comm.), but the most recent breeding record in this province was in 1946 (C. Werschler pers. comm., in Cooper et al., 1998). Lewis’s Woodpecker is currently considered to be a vagrant species in the province of Alberta (Semenchuk 1992). In British Columbia, Lewis’s Woodpecker breeds locally in the southern interior portion of the province where the limits of its range extend from Williams Lake in the north, east to Invermere, west to Lillooet Range near Lytton, and south to the Canada-U.S.A. border (Campbell et al., 1990, Siddle and Davidson 1991). Prior to the 1960’s, thedistribution of Lewis’s Woodpecker included coastal populations on Vancouver Island, and the lower Fraser River Valley; these populations were extirpated by 1962 (Davidson 1966) and 1964 (Campbell et al., 1990), respectively.

In British Columbia, Lewis’s Woodpecker achieves its greatest densities in the Okanagan Valley (Cannings et al., 1987) and Thompson Basin areas (Cooper et al., 1998), both within the Kamloops Forest Region, near the center of its Canadian range. In regions peripheral to these core areas, Lewis’s Woodpecker is less common. Between Manning Park and Williams Lake, along the western range limit, it occurs only in localized sites (Siddle and Davidson 1991). Though the species regularly nests in areas such as Kamloops, Grand Forks, Midway and Rock Creek, the numbers in these areas are generally small (Siddle and Davidson 1991).

Non-breeding

As opportunistic feeders, Lewis’s Woodpeckers may wander large distances after the breeding season (Tobalske 1997). Single birds have been recorded as far west as the Queen Charlotte Islands, and as far north as isolated lakes near Vanderhoof (Campbell et al., 1990). Small numbers winter in the Okanagan Valley (Cannings et al., 1987).

Protection

Under the Migratory Birds Convention Act of 1994 in the U.S.A. and Canada, and the British Columbia Wildlife Act of 1982 in British Columbia, Lewis’s Woodpecker is protected from direct unlawful persecution. Although the Forest Practices Code of British Columbia contains some guidelines to address habitat requirements of Lewis’s Woodpecker, S. Cannings (pers. comm.) has indicated that these guidelines, as currently worded, are unlikely to protect many nest sites of the species. There are a number of protected areas with suitable habitat for Lewis’s Woodpecker in British Columbia, including Okanagan Mountain Park, Vaseux Lake National Wildlife Area, Ecological Reserve No. 7, Osoyoos Lake Oxbows, Okanagan River, Inkaneep Park, Cawston Slough, and Ecological Reserve No. 100 (Cooper et al., 1998). However, much suitable habitat is on private land, in valley bottoms and on lower hill slopes, where ponderosa pine and black cottonwood tend to occur (Cooper et al., 1998).

Population Sizes and Trends
Size

Due to its globally-sporadic and locally-clumped distribution, accurate estimates of population sizes for Lewis’s Woodpecker at the landscape scale are extremely difficult to make (DeSante and Pyle 1994; Tobalske 1997; Cooper et al., 1998), and are probably quite sensitive to varying degrees of sampling effort. Consequently, there are no reliable estimates of the global population size of Lewis’s Woodpecker (Tobalske 1997).

In British Columbia, which contains essentially the entire Canadian population, Siddle and Davidson (1991) estimated that there were 350-600 breeding pairs based on field surveys in 1990, interviews with naturalists, a literature review, and a review of the B.C. Nest Record Scheme (see Table 1). Cooper et al., (1998) stressed that this was a minimum estimate, and a subsequent inventory in the East Kootenay Trench has yielded far more active nests than expected (85), suggesting that the original estimate may have been too low (J.M. Cooper, pers. comm.). Thus, the minimum population size in British Columbia (and therefore Canada) is probably at least as high as the upper limit of 600 proposed by Siddle and Davidson (1991).

Due to a lack of population size estimates throughout its range, it is difficult to suggest what percentage of the global population breeds in Canada. Inspection of the range map for the species (Figure 1) suggests that it is less than 10%, though it is probably closer to 5% (J.M. Cooper, pers. comm.).

Trends

During the 20th century, the global population of Lewis’s Woodpecker has declined (Bock 1970; Tobalske 1997; Cooper et al., 1998). From Breeding Bird Survey and Christmas Bird Count data, Tashiro-Vierling (1994) estimated a population decline of approximately 60% since the 1960’s. (Ehrlich et al., 1988) suggested that the decline may have stabilized, though more data are needed on long-term population trends to evaluate this claim.

In the United States, local or regional declines have been documented in Oregon, Montana, California and Utah (Weydemeyer 1975; Tate 1981; Sorensen 1986; Siddle and Davidson 1991; DeSante and George 1994), whereas numbers have actually increased in the plains of southeastern Colorado (Hadow 1973; Tashiro-Vierling 1994). However, due to its sporadic distribution and infrequent status throughout its range, Tobalske (1997) advised caution when interpreting local population trends for Lewis’s Woodpecker. In a single locality, population size may change dramatically from year to year, sometimes disappearing altogether and reappearing years later (Bock 1970; Siddle and Davidson 1991). Despite the difficulty of interpreting local trends, it should be stressed that there is a strong consensus that populations have declined at regional and global scales over a period of decades (Tashiro-Vierling 1994; Tobalske 1997; Cooper et al., 1998).

Table 1. Population estimates of Lewis’s Woodpecker for different localities of British Columbia(taken from Siddle and Davidson 1991).

Region Population estimate (pairs)

Manning Park-Keremeos 1-10

Upper Fraser Canyon 10-40

Cache Creek to Williams Lake 5-20

Kamloops to Pritchard 10-30

Merritt 4-10

Invermere 5-10

Skookumchuck 2-4

Extreme southeastern British Columbia 5-10

Trail, Nelson, Castlegar 5-10

Grand Forks to Rock Creek 40-60

Keremeos to Anarchist Mountain 75-100

Oliver to Okanagan Falls 50-75

Skaha Lake to Naramata 50-75

Summerland 50

Okanagan Lake Provincial Park 2-4

Kelowna 20-50

Vernon 10-20

TOTAL 344-528

In Canada, the population of Lewis’s Woodpecker has clearly declined, though it is debatable whether or not it has now stabilized (Cooper et al., 1998). The transient nature of much of the suitable habitat in British Columbia (e.g. successional forests with standing snags) makes it difficult to determine whether the Canadian population is currently declining, increasing, or stable. However, to get a general idea of current population trends, Siddle and Davidson (1991) and (Cooper et al., 1998) conducted a thorough series of interviews with naturalists and biologists throughout the range of Lewis’s Woodpecker in British Columbia. Most interviewees perceived that local populations were either stable or in decline, while none indicated that populations were increasing (Cooper et al., 1998).

Prospects for the population in the near future, and in the long term, are highly dependent on how forests are managed in the southern interior of British Columbia. Clearing of old-growth, open ponderosa pine stands would cause the population to decrease, whereas leaving standing snags following managed burns or cuts may result in population increases (Cooper et al., 1998; see Habitat and Limiting Factors sections). The balance of such management regimes will determine the future trends in the population of Lewis’s Woodpecker in Canada.

Habitat
Habitat characteristics

Throughout its North American range, including Canada (interior British Columbia), Lewis’s Woodpecker breeds in three main habitat types: (1) open, mature ponderosa pine forests, (2) riparian black cottonwood stands adjacent to open areas, and (3) recently logged or burned coniferous forests with standing snags (Bock 1970; Tobalske 1997; Cooper et al., 1998). The presence of large, standing-dead or dying trees (snags) for nest cavities, and relatively open areas for feeding, appear to be essential habitat features (Bock 1970; Sousa 1983; Tobalske 1997; Cooper et al., 1998). Although its distribution is generally coincident with that of ponderosa pine, Lewis’s Woodpecker is able to breed in a range of habitats that contain these essential features. In addition to the main habitats listed above, breeding birds have been observed in oak scrub, in a variety of coniferous forests, in orchards and other agricultural areas, and even in urban areas if they contain mature trees (Bock 1970; Raphael and White 1984; Campbell et al., 1990; Tashiro-Vierling 1994; Vierling 1997; Cooper et al., 1998).

Despite the ability of Lewis’s Woodpecker to breed in a variety of habitats, Siddle and Davidson (1991) strongly stressed the importance of mature, open ponderosa pine stands for the long-term maintenance of the population in British Columbia. Although the species has been known to nest in at least 16 species of tree in British Columbia (B.C. Nest Records Scheme), Siddle and Davidson (1991) calculated that about 90% of all nests were either in, or adjacent to, mature, open ponderosa pine forests where the species is most often observed feeding. These forests are thus considered their primary habitat in British Columbia (Cooper et al., 1998). Although at least 47% of nests documented by Siddle and Davidson (1991) in British Columbia were not in ponderosa pine trees, secondary habitats are usually extensions of primary habitat, and generally provide suitable nesting sites only temporarily (e.g. mid-successional post-fire stands; Siddle and Davidson 1991).

Habitat availability

Description of the distribution of suitable habitat is scale-dependent. In Canada, open ponderosa pine and black cottonwood forests suitable for breeding of Lewis’s Woodpecker are restricted to the southern interior of British Columbia. Within this area, the distribution of primary habitat is fragmented, with suitable nesting sites “scattered over large geographic regions ... concentrations do not exist” (Cooper et al., 1998). Siddle and Davidson (1991) provide a detailed account of Lewis’s Woodpecker abundance in different regions of southern interior British Columbia. While the total area of suitable ponderosa pine and black cottonwood habitat in British Columbia is unknown, the regional abundance of Lewis’s Woodpecker generally increases with the availability of primary habitat, which is patchy (fragmented) both within and among regions (Siddle and Davidson 1991).

Trends in habitat availability

The decline in the population of Lewis’s Woodpecker can be attributed primarily to declines in the quantity and quality of suitable habitat (Cooper et al., 1998). In the early part of this century, the quantity of ponderosa pine and cottonwood forests was severely reduced by widespread clearing of forests. However, the rate of decline of suitable habitat has likely decreased since widespread logging of ponderosa pine ceased in British Columbia (Cooper et al., 1998). Recently, while forests continue to be logged and cleared for human developments, declining habitat quality has been more important than outright habitat loss for Lewis’s Woodpecker. Most importantly, fire suppression, or cutting of snags and old “veteran” trees quickly renders otherwise suitable breeding habitat unsuitable for Lewis’s Woodpecker (Cooper et al., 1998). When fires are suppressed, many ponderosa pine forests become dense, and often invaded by Douglas fir, thus eliminating the open feeding areas necessary for Lewis’s Woodpecker (see Limiting Factors section). However, the structural habitat characteristics of open forests may be easily restored by controlled burning of closed forests, which would allow the expansion of local populations. Although logged areas provide only temporary breeding habitat, leaving standing trees and snags after logging may considerably increase the habitat available for Lewis’s Woodpecker. One example of population expansion was documented in southeastern Colorado, where expansion has occurred as a result of the maturation of large cottonwoods along the edges of cornfields (Hadow 1973; Tashiro-Vierling 1994).

The current rate of decline varies among regions, and depends on human land-use and management. For instance, in the core of the species’ distribution in Canada - the Okanagan Valley - urban and agricultural developments are occurring at a high rate, with a consequent high rate of Lewis’s Woodpecker habitat loss (Cooper et al., 1998). In the East Kootenay Trench, the rate of habitat loss is slower, mainly resulting from the loss without replacement of mature, senescing trees (J.M. Cooper, personal communication). The overall net result of human land-use and management across British Columbia is a decline in the quantity and quality of habitat for Lewis’s Woodpecker.

General Biology
Reproductive capability

There are no known data on breeding age for Lewis’s Woodpecker, but maturity is probably attained at one year (Tobalske 1997). Bock (1970) suggested that Lewis’s Woodpeckers form long-term or permanent mating pairs, perhaps as a result of strong nest-site fidelity. One brood is reared each year. The clutch size is usually 5-9 eggs (Bock 1970), with an average of about 6-7 eggs (Bent 1939, Godfrey 1986, Koenig 1987), a relatively large clutch size compared to other woodpeckers. In British Columbia, (Campbell et al., 1990) observed clutch sizes ranging from 2 to 8 eggs, with 63% of active nests containing 4-6 eggs (n = 30).

Both sexes participate in incubation (Bock 1970) which lasts about 14 days (Winkler et al., 1995). The nestling period usually lasts about 4-5 weeks (Bock 1970; Short 1982), although fledging has been observed after only three weeks in some nests in British Columbia (Campbell et al., 1990). There are few data on annual reproductive success for Lewis’s Woodpecker. In cottonwood habitat in Colorado, 60% of 42 nests produced at least one fledgling, with a mean of 2.1 fledglings per successful nest (Tashiro-Vierling 1994). Eighty-one percent of 150 nests in burned ponderosa pine habitat in Idaho produced at least one fledgling (Saab and Dudley 1996). Out of 20 nests observed by (Campbell et al., 1990) in British Columbia, the number of fledglings per nest ranged from 1 to 5 with a mean of 2.8.

Lewis’s Woodpeckers generally breed as solitary pairs, but the species is also known to nest in loose colonies in some regions (Currier 1928; Bock 1970). In British Columbia, Siddle and Davidson (1991) often observed solitary breeding pairs in mature ponderosa pine forests, and loose colonies in secondary habitat types such as cottonwood stands, suburban areas, and forest burns. One instance of three breeding pairs nesting in a single tree (mature ponderosa pine) was recently reported in the East Kootenay Trench region of British Columbia (Cooper et al., unpubl.). (Cooper et al., 1998) suggested that loose colonies likely form as a result of local concentrations of cavity-excavating opportunities and abundant supplies of insects for food, rather than actual cooperative breeding.

Lewis’s Woodpecker requires open forested habitats with large diameter dead or dying trees for breeding (Sousa 1983; Tobalske 1997; Cooper et al., 1998; see Habitat section). In British Columbia, nests are most commonly found in large, dead or dying ponderosa pine or black cottonwood trees, generally in valley bottoms and foothills, and rarely on mountain slopes (Campbell et al., 1990; Cooper et al., 1998). Because Lewis’s Woodpecker is not well adapted to cavity excavation, it commonly uses existing nest holes or natural cavities (Bock 1970).

There is no information concerning the reproductive rate of Lewis’s Woodpecker in Canada or elsewhere, and it is unknown whether or not current reproduction replaces mortality (Siddle and Davidson 1991; Cooper et al., 1998).

Species movement

Except for a small number of birds that are year-round residents in the southern Okanagan Valley, Lewis’s Woodpeckers in British Columbia are migratory (Cooper et al., 1998). Following the breeding season, nomadic flocks, seldom with more than 40 birds, are often observed feeding opportunistically in a variety of habitats in their local ranges (Cannings et al., 1987; Cooper et al., 1998). Fall migration generally begins in August and continues through the month of September, although a few individuals may be seen migrating in British Columbia as late as the end of October (Campbell et al., 1990). In spring, Lewis Woodpecker’ generally returns to British Columbia during late April and early May (Cannings et al., 1987; Campbell et al., 1990). There are no data on specific migration distances and routes, though they are thought to vary considerably from year to year depending on locally abundant food sources (Tobalske 1997).

Behaviour/adaptability

In areas remote from human activity, Lewis’s Woodpeckers are fairly shy birds and seem to be affected by prolonged interference of humans at or near the nest (Bock 1970; Siddle and Davidson 1991). In such circumstances, adults will not enter the nest or feed the young and may even desert their young if the nest cavity is disturbed (Bock 1970; Tashiro-Vierling 1994; Siddle and Davidson 1991). In contrast, some Lewis’s Woodpeckers in British Columbia have become habituated to human activity in areas such as urban parks, orchards, and woodlands next to public beaches (Siddle and Davidson 1991). For instance, one active nest was observed in a power pole in a downtown Penticton parking lot (Cannings et al., 1987). However, the majority of breeding pairs nest in areas with little human activity, and are generally considered to be more sensitive to human presence than other woodpeckers such as sapsuckers, Hairy Woodpecker, and Downy Woodpecker (Cooper et al., 1998).

Lewis’s Woodpecker feeds on a variety of insects, fruits, and seeds and shows little feeding specialization compared to other North American woodpeckers. The species is an opportunistic forager, and its diet shifts seasonally to take advantage of locally abundant food sources such as hatching insects and fruit crops (Bock 1970). Beetles, ants, bees, wasps, grasshoppers, spiders, and true bugs are the main insects eaten by Lewis’s Woodpecker (Beal 1911; Snow 1941). Nesting adults or post-breeding birds will eat both natural and commercial fruit crops such as cherries, apples, and crabapples, particularly in the Okanagan Valley (Cannings et al., 1987).

Lewis’s Woodpecker has shown an ability to adapt to certain environmental changes. Being a non-specialized feeder, the species has readily taken advantage of the seasonally abundant food supply provided by nut and fruit orchards in British Columbia (Siddle and Davidson 1991). Human settlement has not prevented Lewis’s Woodpecker from breeding in much of its bottomland habitat, including riparian zones and urban parks, as long as sufficient large shade trees are present (Siddle and Davidson 1991). Furthermore, forests that have been recently burned, either naturally

or by humans, may in fact be optimal habitat for Lewis’s Woodpecker, although the suitability of the habitat is only temporary (Cooper et al., 1998).

There are other environmental changes to which the species has not been able to adapt. When ponderosa pine forests are allowed to become too dense, or when snags are removed from open areas, these habitats become unusable by Lewis’s Woodpecker. Nesting pairs have often disappeared from urban-suburban areas when mature trees with many natural cavities are removed (Cooper et al., 1998).

Limiting Factors

Perhaps the most important limiting factor for Lewis’s Woodpecker is the availability of old trees and snags for nesting (Raphael and White 1984; Tobalske 1997; Cooper et al., 1998). (Cooper et al., 1998) provide numerous specific examples of breeding pairs that disappeared from different areas of British Columbia due to the loss of nest trees, which may occur as the result of various human activities. In areas of British Columbia such as the Okanagan Valley and Penticton, large trees and snags are frequently removed for development projects such as the building of malls and houses, and road construction (Cooper et al., 1998). In (sub)urban and rural areas, suitable nest trees may be removed by private citizens or municipal governments for human-safety or aesthetic reasons. While large-scale logging of ponderosa pine is no longer prevalent in British Columbia, large “veteran” trees are still removed by helicopter logging in some areas, particularly on steep slopes; firewood cutters also remove large dead or senescing trees from accessible areas (Cooper et al., 1998). In the past, snags were routinely removed from managed forests for the purposes of disease control and safety. However,( Cooper et al., 1998) indicate that this is no longer routine practice, and that protection of these habitat features represents a promising avenue for stemming population decline.

Fire suppression affects both the availability of suitable nest trees, and the overall quality of the habitat. In the absence of fire in ponderosa pine forests, dense stands tend to develop which are entirely unusable by Lewis’s Woodpecker (Bock 1970). Fire suppression may also lead to the invasion of Douglas fir, in which Lewis’s Woodpecker rarely nests (Siddle and Davidson 1991; Tobalske 1997). Fires of sufficient severity will often result in the death of some old or senescing trees, thus creating new suitable nest trees; therefore, suppression of fire will attenuate or eliminate this process of habitat creation (Cooper et al., 1998).

The European Starling (Sturnus vulgaris) has been implicated as an important non-native competitor with Lewis’s Woodpecker for nest cavities (Bock 1970; Weber 1980). While more recent observations indicate that Lewis’s Woodpecker often dominates these interspecific interactions (Cannings et al., 1987; Tashiro-Vierling 1994; but see Sorensen 1986), starlings do sometimes evict nesting pairs of Lewis’s Woodpecker from their nest cavity (Cooper et al., 1998), and these interactions must certainly impose an energetic cost. While no studies have specifically evaluated the effect of competition with the European Starling on nesting success or reproductive effort in Lewis’s Woodpecker, other species in the genus Melanerpes have been shown to lose nest cavities to starlings (Troetschler 1976; Ingold 1989, 1994).

(Cooper et al., 1998) list three additional factors which may limit the population size of Lewis’s Woodpecker in British Columbia: pesticides, grazing, and loss of winter habitat. These factors have been suggested as possible limiting factors by other authors (Sorenson 1986; Jackman 1974; Cooper et al., 1998), but very little is actually known about their effects on Lewis’s Woodpecker.

Special Significance of the Species

Because consistent population declines had been observed since the 1960’s, Lewis’s Woodpecker was added to the Audubon Society Blue List in 1975 (Tate 1981). The species was upgraded to a Species of Special Concern in 1982 (Tate and Tate 1982). In British Columbia, following a drastic decline on Vancouver Island, Stirling (1966) considered the species to be a bird of special concern. In 1980, the species was part of a proposed list of rare and endangered bird species in British Columbia (Weber 1980), and in the South Okanagan Critical Areas Program, it has been listed as a Priority 2 species (Hlady 1990). Lewis’s Woodpecker is currently on the B.C. Wildlife Branch Blue List (1996), due to declines in population size and suitable habitat.

Because of its conspicuous and attractive coloration, the Lewis’s Woodpecker is easily recognized, and a draw for birdwatchers in British Columbia (Cooper et al., 1998). As Lewis’s Woodpecker often feeds on orchard fruit crops, there has been some history of farmers shooting the species (Parham 1937). However, current damage of the species on fruit crops is relatively small, and not of serious concern to fruit farmers in British Columbia (Cooper et al., 1998). The species is not generally shot or trapped for any other reason (Tobalske 1997).

Of the six species of Melanerpes in North America, three occur in Canada: the Red-headed Woodpecker (M. erythrocephalus), the Red-bellied Woodpecker (M. carolinus), and Lewis’s Woodpecker. The Red-headed Woodpecker is listed as Threatened in Canada (COSEWIC 1998), and the breeding population in Canada of the Red-bellied Woodpecker consists of only a few localities in extreme southwestern Ontario (Peck and James 1983). Two woodpeckers which, along with Lewis’s Woodpecker, are restricted to southern interior British Columbia in Canada, and require snags for nesting, are the White-headed Woodpecker (Picoides albolarvatus) and Williamson’s Sapsucker (Sphyrapicus thyroideus). Both species are considered at risk in British Columbia (Cooper et al., 1998), and the White-headed Woopecker is considered Threatened in Canada (COSEWIC 1998).

Evaluation and Proposed Status

The range of Lewis’s Woodpecker in Canada is restricted to southern interior British Columbia, where its distribution is generally sparse with local concentrations in areas of suitable habitat. During the 20th century there has been a clear population decline both in Canada and North America, with extirpation having occurred in at least two regions of coastal British Columbia. Though it is uncertain whether or not the population is still in decline, most observers interviewed by Siddle and Davidson (1991) perceived that local populations were either stable or in decline, while none felt that they were increasing. Population declines can be attributed primarily to declines in both the quantity and quality of suitable habitat. Continued human development in the core of the species range, and current forest management practices suggest that habitat decline will continue. However, relatively minor modifications to current forest management practices, such as leaving standing snags following cutting, or prescribed burning or thinning of dense ponderosa pine forests, have the potential to actually create suitable habitat for Lewis’s Woodpecker.

Due to declines in habitat availability, and consequent population declines, we recommend that Lewis’s Woodpecker be assigned the status of Vulnerable in Canada. The great potential for habitat improvement, and the ability of the species to adapt to certain types of human disturbances (e.g. logged or burnt forests with standing snags) indicate that Threatened status is not currently appropriate. Continued declines in suitable habitat would, however, constitute a real threat to the species in Canada.

Technical Summary

Melanerpes lewis

Lewis’ss Woodpecker

Pic de Lewis

Population name (if applicable)] none

[Range of Occurrence in Canada (by province / territory / ocean)] BC

Extent and Area information

· extent of occurrence (EO)(km²) : ca. 30,000 km2

· specify trend (decline, stable, increasing, unknown): stable

· are there extreme fluctuations in EO (> 1 order of magnitude)?No

· area of occupancy (AO) (km²) : ca. 2000 km2

· specify trend (decline, stable, increasing, unknown) : stable or slow decline

· are there extreme fluctuations in AO (> 1 order magnitude)?No

· number of extant locations : n.a.

· specify trend in # locations (decline, stable, increasing, unknown) : n.a.

· are there extreme fluctuations in # locations (>1 order of magnitude)?n.a.

· habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat : decline

Population information

· generation time (average age of parents in the population) (indicate years, months, days, etc.) : 1+ years

· number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values) : 1000-2000

· total population trend: specify declining, stable, increasing or unknown trend in number of mature individuals : stable or slow decline

· if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period) : n.a.

· are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)? No

· is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise) populations between which there is little exchange, i.e., <1 successful migrant / year)?No

· list each population and the number of mature individuals in each : n.a.

· specify trend in number of populations (decline, stable, increasing, unknown)n.a.

· are there extreme fluctuations in number of populations (>1 order of magnitude)?No

Threats (actual or imminent threats to populations or habitats) [add rows as needed]

- urban and agricultural developments destroy nest sites and degrade habitat

- fire suppression causes forest ingrowth and reduced number of nest snags

- removal of large snags through firewood cutting or public safety concerns

- Starling nest-site competition

- pesticides may be a threat, particularly in orchard and vineyard areas

- some mortality due to vineyard netting

- heavy grazing may degrade habitat for prey species (large flying insects)

Rescue Effect (immigration from an outside source) : High

· does species exist elsewhere (in Canada or outside)?Yes

· status of the outside population(s)?Decreasing?

· is immigration known or possible?Yes

· would immigrants be adapted to survive here?Yes

· is there sufficient habitat for immigrants here?Yes

Quantitative Analysis

Acknowledgements

Information in this report was taken largely from two other reports on the status of the Lewis’s Woodpecker in British Columbia, one published in 1991 by Chris Siddle and Gary Davidson, the other in 1998 by John M. Cooper and the two previous authors. John M. Cooper provided further information on current population surveys in British Columbia, and offered insight into future prospects in B.C. We thank David Fraser for providing the two B.C. status reports and a number of useful leads. Steven Brechtel and Syd Cannings offered their expert opinions on the current and future status of Lewis’s Woodpecker in Alberta and British Columbia respectively. Thanks to Gilles Seutin for providing useful comments and suggestions during the writing of this manuscript.

Funding for the preparation of this status report provided by the Canadian Wildlife Service, Environment Canada.

Literature Cited

B.C. Wildlife Branch. 1996. Birds, Mammals, Reptiles, and Amphibians at Risk in British Columbia. Ministry of Environment, Lands and Parks, Wildlife Branch, Victoria, B.C.

Beal, F.E.L. 1911. Food of the Woodpeckers of the United States. U.S. Dept. Agr. Biol. Surv. Bull. 37.

Bent, A.C. 1939. Life Histories of North American Woodpeckers. U.S. Natl. Mus. Bull. No. 174. Smithsonian Inst., Washington, DC.

Bock, C.E. 1970. The ecology and behavior of the Lewis’s Woodpecker (Asyndesmus lewis). University of California Publications in Zoology, 92: 1-100.

Campbell, R.W., N.K. Dawe, I. McTaggart-Cowan, J.M. Cooper, G.W. Kaiser and M.C.E. McNall, 1990. The Birds of British Columbia. Volume 2. The Royal British Columbia Museum, Victoria, and The Canadian Wildlife Service, Delta, B.C.

Cannings, R.A., R.J. Cannings, and S.G. Cannings. 1987. Birds of the Okanagan Valley, B.C. Royal B.C. Mus., Victoria, BC.

Cooper, J.M, C. Siddle and G. Davidson. 1998. Status of the Lewis’s Woodpecker (Melanerpes lewis) in British Columbia. Wildlife Working Report No. WR-91, Ministry of Environment, Lands and Parks, Wildlife Branch, Victoria, BC.

COSEWIC. 1998. List of Canadian Species at Risk, April 1998. Committee on the Status of Endangered Wildlife in Canada.

Currier, E.S. 1928. Lewis’s Woodpeckers nesting in colonies. Condor, 30: 356.

Davidson, A.R. 1966. Annotated List of Birds of Southern Vancouver Island. Victoria Natural History Society, Victoria, BC.

DeSante, D.F. and P. Pyle. 1986. Distributional Checklist of North American Birds. Volume 1: United States and Canada. Artemisia Press, Lee Vining, CA.

DeSante, D.F. and T.L. George. 1994. Population trends in the landbirds of western North America. In A Century of Avifaunal Change in Western North America (J.R. Jehl Jr. and N.K. Johnson, eds.). Studies in Avian Biology No. 15.

Ehrlich, P.R., D.S. Dobkin and D. Wheye. 1988. The Birder’s Handbook. Simon and Schuster, New York, NY.

Gilligan, J., M. Smith, D. Rogers, and A. Contreras. 1994. Birds of Oregon: Status and Distribution. Cinclus Publ., McMinville, OR.

Godfrey, W.E. 1986. The Birds of Canada. Natl. Mus. Can., Ottawa, ON.

Hadow, H.H. 1973. Winter ecology of migrant and resident Lewis’s Woodpeckers in southeastern Colorado. Condor, 75: 210-224.

Hlady, D. 1990. South Okanagan Conservation Strategy 1990-1995. Ministry of Environment, Lands and Parks, Wildlife Branch, Victoria, B.C.

Howell, S.N.G. and S. Webb. 1995. A Guide to the Birds of Mexico and Northern Central America. Oxford Univ. Press, New York.

Ingold, D.J. 1989. Nesting phenology and competition for nest sites among Red-headed and Red-bellied woodpeckers and European Starlings. Auk, 106: 209-217.

Ingold, D.J. 1994. Influence of nest-site competition between European Starlings and woodpeckers. Wilson Bulletin, 106: 227-241.

Jackman, S.M. 1974. Woodpeckers of the Pacific Northwest: their characteristics and their role in the forests. M.Sc. Thesis, Oregon State Univ., Corvallis, OR.

Koenig, W.D. 1987. Morphological and dietary correlates of clutch size in North American woodpeckers. Auk, 104: 757-765.

Parnham, H.J. 1937. A Nature Lover in British Columbia. Witherby, London, UK.

Peck, G.K. and R.D. James. 1983. Breeding Birds of Ontario: Nidiology and Distribution. Volume 1: Nonpasserines. The Royal Ontario Museum, Toronto, ON.

Raphael, M.G. and M. White. 1984. Use of snags by cavity-nesting birds in the Sierra Nevada. Wildlife Monographs, 86: 1-66.

Saab, V.A. and J. Dudley. 1996. Why do burned forests provide conditions for nest site convergence among cavity-nesting birds? Abstract no. 119. 114th Stated Meeting of the Amer. Ornithol. Union, 13-17 August 1996, Boise, ID.

Semenchuk, G.P., ed. 1992. The Atlas of Breeding Birds of Alberta. Fed. Of Alberta Nat., Edmonton, Alberta.

Siddle, C. and G. Davidson 1991. Status of the Lewis’s Woodpecker (Melanerpes lewis) in British Columbia. Report Commissioned by Ministry of Environment, Lands and Parks, Wildlife Branch, Victoria, BC.

Short, L.L. 1982. Woodpeckers of the World. Delaware Mus. Nat. Hist., Greeneville, DE.

Small, A. 1994. California birds: their Status and Distribution. Ibis Publ. Co., Vista, CA.

Snow, R.B. 1941. A natural history of the Lewis’s Woodpecker Asyndesmus lewis (Gray). M.S. Thesis, Univ. Utah, Salt Lake City, UT.

Sorensen, E. 1986. A precipitous decline in Lewis’s Woodpecker in Salt Lake and Davis Counties. Utah Birds, 2: 45-54.

Sousa, P.J. 1983. Habitat Suitability Index Models: Lewis’s Woodpecker. U.S. Fish and Wildlife Service, Washington, D.C.

Stirling, D. 1966. Bird Report (Victoria) Number Four - 1965. Victoria Natural History Society, Victoria, B.C.

Tashiro-Vierling, K.Y. 1994. Population Trends and Ecology of the Lewis’s Woodpecker (Melanerpes lewis) in southeastern Colorado. M.A. thesis, University of Colorado, Boulder.

Tate, J. Jr. 1981. The Blue List for 1981. American Birds, 35: 3-8.

Tate, J. Jr. and D.J. Tate. 1982. The Blue List for 1982. American Birds, 36: 126-135.

Tate, J. Jr. 1986. The Blue List for 1986. American Birds, 40: 227-235.

Tobalske, B.W. 1997. Lewis’s Woodpecker. In The Birds of North America, No. 284 (A. Poole and F. Gell, eds.). The Academy of Natural Sciences of Philadelphia, PA, and the American Ornithologists’ Union, Washington, D.C.

Troetschler, R.G. 1976. Acorn Woodpecker breeding strategy as affected by starling nest-hole competition. Condor, 78: 151-165.

Vierling, K.T. 1997. Habitat selection of Lewis’s Woodpeckers in southeastern Colorado. Wilson Bulletin, 109: 121-130.

Weber, W.C. 1980. A proposed list of rare and endangered bird species for British Columbia. In Proceedings of a Symposium on Threatened and Endangered Species and Habitats in British Columbia and the Yukon. Ministry of Environment, Lands and Parks, Wildlife Branch, Victoria, BC.

Weydemeyer, W. 1975. Half-century record of the breeding birds of the Fortine area, Montana: nesting data and population status. Condor, 77: 281-287.

Winkler, H., D.A. Christie and D. Nurney. 1995. Woodpeckers: a Guide to Woodpeckers of the World. Houghton-Mifflin Co., Boston, MA.

Biographical Summary of the Author(S)

Mark Vellend has a Bachelor’s degree and a Master’s degree from the Department of Biology at McGill University. He is interested primarily in the ecology and genetics of forest plants, but also in the ecology and conservation of birds. Mark is currently a doctoral student in the Department of Ecology and Evolutionary Biology at Cornell University.

Véronique Connolly recently finished a Master’s degree in the Department of Geography at McGill University, where she studied the habitat requirements of Bicknell’s Thrush, a species listed in 1999 as “of special concern” by COSEWIC. She also contributed a book chapter on the biology and conservation of Piping Guans, and is currently working at the Cornell Laboratory of Ornithology.

Page details

Date modified: