Background

The Blenkinsop Valley, especially the area around the lake, has long been recognized as one of the prime birding areas in Greater Victoria. Over the years, however, as trees have been cleared, land drained, and development has encroached upon it, there has been a gradual loss of habitat supporting this avifauna. As such, the area is one of several designated by the Parks and Conservation Committee of VNHS as a "sensitive area" and monitored intermittently.

In recent years, the prospect of trail construction around the lake, plans for a bridge across the water, possible increased use of water for irrigation, and the long-term threat of light rapid transit along the Lochside right-of-way have stressed the need for a more thorough inventory of the bird population in the valley. To this end a one-year weekly bird count was undertaken beginning June, 1992. This article describes the results of that bird survey and incorporates other data collected since 1979 into a monthly checklist of birds. The final section discusses changes in the avifauna since the late 1940s, at which time a detailed survey was undertaken by the Provincial Museum (Hardy, 1956). The article is an abbreviated version of a report on file with the Society.

The survey

A location map of the Blenkinsop Valley is provided, taken from the Blenkinsop Local Area Plan of Saanich. The present survey covered only the central part of the valley, beginning mid-way along Lohbrunner Road, then down Lochside Drive and Trail as far as the lake shoreline. The area covered is considered representative of the valley as a whole, and comprises four main habitats: open fields, woodland margins, hedgerows and trees flanking the lake and Lochside Trail, and the lake itself.

In the construction of a checklist, the data from the weekly surveys were supplemented by other observations in the valley made beyond the geographic limits of the regular weekly survey, as well as by sightings within the regular count area but by other observers. Additional mid-week mini-surveys within the regular count area were also undertaken, especially during the two migration times in the 1992-93 period.

In total, 128 species were recorded in the valley during the 12- month period from the first week of June 1992. This was broken down as 29 species (plus possible Greater Scaup) of water-based birds, 32 non-perching species (plus possible Virginia Rail, Ring- billed Gull and Thayer's Gull), and 62 passerines (plus possible Hammond's Flycatcher).

Monthly checklist

The data from the 1992-93 observations were supplemented by all sightings of irregular species reported for the Blenkinsop Valley in past issues of the Victoria Naturalist or logged in the bird- sighting records program of the Royal B.C. Museum between 1979 and 1988. The combined data set is summarized as a monthly checklist, each month being represented by probability of observation of species. Sightings of irregular species between 1979 and 1988 are represented on the checklist by shading.

All irregular species for which records were actually searched in the Museum database (whether observed in the valley or not) are also presented in a separate table based on the actual frequency of sightings of these species. The values in that table represent the numbers of years (maximum 10) in which a sighting was recorded in that month. Most of these observations were in the area surveyed in the 1992-93 inventory. Some, however, were more frequently reported from the area around the golf course adjacent to Blenkinsop Road: this is especially true of the Yellow-headed Blackbird and some of the owls.

The total number of species on the checklist is 160. Some species that were not seen in 1979-88 (and therefore not listed) have been reported in the last few years. These include Swainson's Hawk (1989 Aug), Sandhill Crane (1990 May) and Long-eared Owl (1990 Dec.?).

The checklist should provide a useful guide to the probablility of seeing different species in the valley, though, of course, certain features of the 1992-93 year may not be replicated in the future. One is the abundance of Steller's Jays in the area that winter. Another is the severe cold spell during January, which led to the lake being frozen for a period of four weeks and resulted in the departure of most of the regular waterfowl. Other chance year-to- year variations are certainly embodied in the checklist.

In addition, it should be noted that not all species that were missed in the 1992-93 count were the subject of a Museum file search. And some which were recorded only once or twice in the 1992-93 survey were also not searched. Included in these categories were Eurasian Wigeon, Canvasback, Greater Yellowlegs, Common Snipe, Olive-sided Flycatcher (missed in 92-93), for which the card files for Grid 92B/6 (Victoria area) were too big to search in the time available.

A separate table is provided showing the numbers of birds seen in each species during the regular weekly bird surveys of 1992-93. These data are expressed as the average number of birds seen per survey in each month. Because of limitations of space, the table is restricted to birds which were observed at least 5 times, on the average survey, in at least one month. These data provide some indication of abundance of birdlife in a way that is not directly conveyed by the checklist.

Highlights

The year's birding provided numerous highlights which made the long cold treks of winter all worthwhile in the end. These included:

three fledgling Pied-billed Grebes seen regularly, with parent, on the lake June 7-27; no grebes were seen during the spring of 1993;

fleeting glimpses around the lake of one or two Green-backed Herons through the spring of 1992 followed by discovery of three fledgings in the first few days of flight on July 26; at least one pair and a separate bird were seen regularly during the spring of 1993;

a Cattle Egret wandering around a paddock in October 1992, finally being chased away by the horses and alighting on a pile of rubber tyres; another was seen in late October 1993 (ET);

a very small, immature Greater White-fronted Goose, believed to be of the tundra race, which arrived at the Marley's Farm on the south east side of the lake in fall migration and which stayed through the winter until the last week of April;

a male Ruddy Duck in full breeding plumage on the lake on May 11;

a brood of four fledgling Cooper's Hawks, first seen in the woods of Faithwood and Broadmead on the west side of the valley on July 26, of which several were seen hunting over the Blenkinsop Valley through the winter;

an unusual pair of Red-tailed Hawks nesting at the top of a tall fir tree in a copse on the east side of the valley, first seen in May of 1992, and then repeatedly through the year. The female was a classic western subspecies but the male was extremely pale (with whitish tail) and thought to be dominantly Krider's in genetic makeup. Two young were fledged in 1992, and two more in 1993. Interestingly, the two young looked quite different, resembling their contrasting parents. First signs of nest rebuilding in 1993 were noted on January 9; mating was observed (by ET) on March 10; first signs of young in the nest were noted on May 10;

an Osprey, seen on two occasions during May, hovering over the lake and fishing successfully;

a Northern Saw-whet Owl, first seen roosting by DA on February 16, and seen several times between then and March 12, by the irrigation ramp boards on the northeast side of the lake;

a Western Kingbird seen flycatching over the fields from a snag on the trail in May and an American Tree Sparrow hawking over the lake edge in November; at least two Eastern Kingbirds were seen in June 1993, but none in the 12 months of survey;

a Yellow-headed Blackbird seen with Brown-headed Cowbirds around horses in the paddocks east of the southern part of the lake on August 21; two more were reported in May 1993 (RBA) in the vicinity of the golf course on Blenkinsop Road.

Use of the valley by birdlife

Waterfowl and marsh birds

The lake is a haven for waterfowl during both migrations and throughout the winter. Although Mallards may number more than 300 at the end of winter (and constitute almost 90% of the waterfowl at that time), the lake is a significant overwintering area for several other species, especially Ring-necked Ducks (with flocks up to 50 birds), and Hooded and Common Mergansers. The lake is rich in fish (mostly introduced catfish and sunfish: Hardy, 1956; and pumpkinseed: Fisheries Branch, 1982) attracting non-breeding Double-crested Cormorants in the spring (as well as Belted Kingfishers from Cordova Bay at all times of the year).

The deserted appearance of the lake in late spring is misleading as male Wood Ducks, in their magnificent breeding plumage, glide in and out of the water lilies. The nesting status of the Wood Ducks is uncertain. No juveniles have been seen and most birds appear to be unattached males. Nesting boxes erected in 1984 were found to be largely in a state of disrepair and six new boxes were installed on the northern part of the lake in March 1993.

A pair of Green-backed Herons nested in 1992 and at least one pair was resident in the summer of 1993. Great Blue Herons are found throughout the year but no breeding adults have been noted. A pair of Mute Swans nested by the edge of the seed orchard in the 1980s (Marley, 1993).

The status of Sora and Virginia Rail is unclear. Neither responded to taped calls during spring 1993, but the high lake water made access to the shoreline difficult in many places and only a small percentage of the periphery was examined. Museum records show observations in up to four of the years 1979-88. One bird, thought to be a Virginia Rail, was very briefly seen after having been flushed from one area of water lilies into another during July 1992.

Raptors

The valley is an excellent area for almost all raptors found in southern Vancouver Island, with regular visits by Merlin during fall migration and by Peregrine Falcon (light-phase, presumed to be tundrius subspecies) and Sharp-Shinned Hawk in the winter. Red-Tailed Hawk and Cooper's Hawk are resident all year in the valley. A Northern Harrier was seen flying over the valley on two occasions, but none has been seen hunting in the area.

Shorebirds

Killdeer are common (and nest) in the fields, but, in general, the valley is not a good area for shorebirds. The steep lake edge is masked by water lilies and cat-tails, with little habitat for small waders. Flooded fields near the lake are reported to be good areas for shorebirds in spring migration (especially in 1984- 86), but few were seen in 1992-93 which was characterized by an unusually dry winter and early spring. The exception was a pair of Spotted Sandpipers seen several times in the last few weeks of May and thought to be nesting. Common Snipe was seen on only one occasion.

Swallows

The open fields, and especially the lake, are excellent areas for all swallow species, although Bank Swallow and Purple Martin have only been reported in migration. Tree Swallows appear to be more common here than in many areas of the Saanich Peninsula, especially in 1993, and a pair is believed to have nested in the Wood-Duck nesting box opposite the VNHS viewing blind. The blind is an ideal spot for viewing swallows, especially on overcast days.

Other passerines

The hedgerows flanking the trail to the lake, and the riparian thickets around the lake, are rich in small birds during migration and, to a lesser extent, during the summer. Of the warblers, only Yellow Warblers (about 8 singing males), a few pairs of Orange- crowned Warblers and Common Yellowthroats (the latter more common in the riparian thickets) appear to have nested in 1992 and 1993. The nesting status of Warbling Vireo, seen frequently during late summer 1992, is unclear: two singing birds of this species were seen in the more wooded part of Lochside Trail north of Lohbrunner in June 1993. The trail is well-known for the song of the Black- headed Grosbeak throughout the latter half of May and into June. At least six males were regularly seen on the trail or flying across the lake. A pair of House Wrens also nested on the trail in 1992 and two were seen at the same site the following year. Other more common species use the trail for breeding, including Brown-headed Cowbirds.

Comparison with 1940s survey

The survey reported by Hardy (1956) covered the period 1945-1950 and involved surveys once a week. The total number of species seen in that time was 110. This compares with 128 seen during the 1992-93 survey.

The longer duration of Hardy's survey might be expected to have resulted in the sighting of a greater number of rare or irregular species than were recorded in the one-year VNHS survey. However, while there were 23 species observed in the Hardy survey that were not seen in the VNHS survey, there were 41 species observed in the 1992-93 survey that were not observed by Hardy.

Among those that were observed by Hardy but not recorded in 1992- 93, many have presumably disappeared with the change in habitat. The exact land use at the time of the 1940s survey was, however, not detailed by Hardy. The main pattern of fields appears to have been the same as today though Hardy mentions extensive logging (in the early 1950s) on the north and west side of the lake. Hardy also mentions the removal of "islands" of old tree cover that formed part of the fields as late as the 1940s. The old railway (the bed of which now forms Lochside Trail) was discontinued about 1934, though the trestle was not dismantled until 1956.

Species that have disappeared, or at least decreased in numbers since Hardy's survey, include Blue Grouse and Ruffed Grouse (both rare in 1940s) and Western Screech Owl (seen by Hardy in woods that were subsequently logged, and reported since only infrequently), Lewis' Woodpecker (apparently not seen by Hardy but reported in the 1920s), Olive-sided Flycatcher (frequently found singing from tree tops and apparently nesting in the valley in the 1940s), Eurasian Skylark (last reported in 1980) and Western Meadowlark (both common in the 1940s in fields close to the lake). Chipping Sparrow (reported by Hardy as a common summer resident in the open oak glades) was not observed during our 12-month survey, but two were seen in July 1993 in the trail hedgerow, presumably in post-breeding dispersal.

Others recorded by Hardy, but not in 1992-93, may have become more infrequent in the valley simply because of the overall decrease in numbers on southern Vancouver Island. These include Redhead (seen 8 times by Hardy, but not in 1979-88), American Kestrel (seen in autumn migration but only three times in 1979-88), Sora (reported by Hardy to be a regular visitor to the lily pads, but seen in only half the years 1979-88) and Western Bluebird (seen during migration in the open fields, but not in 1979-88).

Others seen by Hardy but not in 1992-93 were: Red-breasted Merganser (occasional winter visitor), Golden Eagle and Rough- legged Hawk (2 sightings), Herring Gull (occasionally in flocks with Glaucous-winged Gull), Mourning Dove (including the first nesting record for Vancouver Island), Short-Eared Owl (in migration), Common Nighthawk, Black Swift and Purple Martin (seen once or twice in migration), Northern Shrike (seen twice in early spring) and Red Crossbill (seen once). Most of these have been reported by others during 1979-88 and a pair of Common Nighthawks was seen in July 1993. The lack of observation by us in 1992-93 is thought to be mostly chance and not a reflection of a longterm decrease in numbers.

Some of those seen in 1992-93 but not by Hardy may also be simply a matter of chance: a Common Loon high overhead in May 1993; Eurasian Wigeon; Spotted Sandpiper; Thayer's Gull; N. Pygmy Owl and N. Saw-whet Owl; Vaux's Swift; Bank Swallow; Black-throated Grey Warbler; American Tree Sparrow; and Yellow-headed Blackbird. In most cases only a single sighting was made of these species in 1992-93. Thayer's Gull was given separate species status in 1973 and was previously designated Herring Gull (which was observed by Hardy).

Other species seen in 1992-93 but not in the 1940s survey appear to reflect increased numbers on Vancouver Island generally, and in some cases actual range expansions. These include: Cattle Egret; Green-backed Heron; Mute Swan; Blue-winged Teal and Cinnamon Teal; Gadwall; Osprey; Bald Eagle; Peregrine Falcon; California Gull; Rock Dove; Great Horned Owl; Anna's Hummingbird; House Wren and Marsh Wren; European Starling; Lincoln's Sparrow; Brown-headed Cowbird; House Finch and House Sparrow.

The lack of sightings of some of the birds of prey in the 1940s probably has several explanations. Gates (1993) points out that birds of prey were probably much less abundant in the 1940s because of shooting by game wardens and others. Taylor (1993) suggests that the appearance of Peregrine Falcon in the valley may be related to increased numbers of ducks, and that increased observation of Great Horned Owl today may reflect introduction on southern Vancouver Island of the Eastern Cottontail Rabbit in the 1960s.

There are some species which were absent from Hardy's survey that are difficult for us to explain. These include Tree Swallow and Northern Rough-winged Swallow; Fox Sparrow and Song Sparrow. All were seen frequently during 1992-93. In the case of the sparrows, at least, it is difficult to believe that lack of records in the 1940s survey is simply a reflection of the inferior optics and field guides at that time.

Endnote

It is hoped that this survey will be useful to local birders in their future treks in the valley and that it will stimulate similar surveys in other sensitive areas. Another year-long survey has recently been initiated for Rithet's Bog in Saanich.

The present survey perhaps simply confirms what most local birders already know: that the Blenkinsop Lake area is an outstanding region of varied birding habitat. There are not many one- kilometre non-coastal walks in Greater Victoria that can muster over 50 species in spring and 30 species on a frigid winter's day.

Some of the regular species noted above are not frequently found elsewhere in the Greater Victoria region. These include Green- backed Heron and Black-headed Grosbeak, while breeding records for Pied-billed Grebe, Wood Duck and Spotted Sandpiper are also believed to be relatively few in the Victoria area.

References

Fisheries Branch, 1982. Blenkinsop Lake: Lake Survey Data. Fisheries Branch, Ministry of Environment, Lands and Parks, British Columbia. Internal report.

Gates, B.R., 1993. Personal communication.

Hardy, G.A., 1956. Notes on the flora and fauna of the Blenkinsop Lake area on southern Vancouver Island, British Columbia. Reprinted from the Report of the Provincial Museum of Natural History and Anthropology, Victoria, 42 pp.

Marley, B., 1993. Personal communication. Local landowner.

Taylor, K., 1993. Personal communication.

Acknowledgements

More than half the regular surveys undertaken in 1992-93 were done with Gordon Hart who added an important element of credibility to the work by providing ears as well as many years of birding experience. Thanks are also due to many others who assisted in these surveys: Jerry and Gladys Anderson; Brent Beech; Tony Embleton; Tom Gillespie; Doreen Loosmore and Morwyn Marshall; Mike McGrenere; Flo Pikula and Ellen Tremblay (ET).

RBA denotes the VNHS Rare Bird Alert. David Allinson (DA) and Flo Pikula provided Christmas and Spring Bird Count data for the southern and northern parts of the valley.

Access to the bird-sighting card files of the RBC Museum was facilitated by Wayne Campbell, Michael McNall and Michael Shepherd. Acknowledgement is also accorded to all the participants of the carding program whose observations are used in this report.

Bryan Gates is thanked for his thorough review of an earlier draft. Keith Taylor provided helpful comment on changes in species presence since the 1940s survey.