Species diversity on local counts remains healthy, but many populations are decreasing in number
Peterborough Examiner – January 17, 2025 – by Drew Monkman
“Wow! There must be at least 20 chickadees that have flown in,” I exclaimed to my friend Brian. “All you do is pish a bit, and they appear like magic. I think we’re over 150 for the day.” While much of this year’s Peterborough Christmas Bird Count felt slow at times, at least we could count on these ubiquitous birds to bolster our list.
The Christmas Bird Count is the world’s longest-running citizen science project. The counts are organized at the local level, often by a naturalist club. The count area is a circle, measuring 24 kilometres in diameter. The circle is then sub-divided into sectors, each of which is covered by a different group of birders whose goal is to find as many species and individual birds as possible. Two counts are held locally – one centered in Peterborough and one in the area surrounding Petroglyphs Provincial Park.
Last year, a record 2677 counts were completed, most of which were in Canada and the U.S. Although 2,380 species and 40.9 million individual birds were tallied, this latter number is actually alarmingly low. In 1972, for example, over 71 million birds were found on less than half as many counts. There are choices we can make to change this pattern of ever-decreasing numbers. Even small changes like drinking bird-friendly coffee, keeping our cats indoors, and making our windows bird-safe can have significant positive impacts.
Highlights of the Peterborough count
The 73rd annual Peterborough Christmas Bird Count took place on December 15, 2024 . The 82 participants found 68 species – just two short of the previous high of 70 in 2021 – and 16,044 individual birds.
“The count provides insight into long-term trends with bird populations,” said count organizer Martin Parker of the Peterborough Field Naturalists. “For example, the arrival and huge increase in Northern Cardinals in our region is well documented by count results. From only single birds in the 1960’s, participants this year found 302. We’re now seeing the same trend with Red-bellied Woodpeckers.”
A first-ever Double-crested Cormorant turned up this year and five species were found in record-high numbers: Red-bellied Woodpeckers (44 vs 28 in 2023), Northern Flickers (9 vs 7 in 2021), Common Ravens (79 vs 70 in 2021), Hermit Thrushes (6 vs 3 in 2021) and Red Crossbills (20 vs 4 in 1969). A surprising 6 Eastern Bluebirds were also observed. “Finding birds like Hermit Thrushes and Eastern Bluebirds, considered by many as summer visitors, is a reflection of our changing climate,” said Parker.
The ten most common birds for the count were Canada Goose (2496), Black-capped Chickadee (2157), Rock Pigeon (1970), European Starling (1495), Mallard (981), Mourning Dove (881), Snow Bunting (834), Dark-eyed Junco (741), and American Robin (569).
As for low numbers, House Sparrow abundance continues to decline with only 167 counted this year. Compare this to the 2,209 found in 1981. House Sparrow populations in North America have declined by nearly 80% since 1969. A primary cause appears to be an insufficient supply of insect food for nestling sparrows. On farms, for example, the decline of insects is linked to modern agricultural practices like the use of agro-chemicals.
House Finch numbers continue to decrease, as well. Only 58 were found this year, while in 1991, 1197 were tallied. A significant outbreak of mycoplasmal conjunctivitis, a bacterial infection that can cause blindness, began affecting House Finches in the mid-1990s. It has led to substantial population declines, particularly in eastern North America.
Two other species that appear to be struggling are the Ruffed Grouse (6 recorded vs 82 in 1979) and the Great Horned Owl (7 recorded vs 40 in 1992). The decline in grouse is likely linked to reduced young forest habitat, which provides essential cover and food, and to warmer winters with less snowfall. Deep snow provides thermal insulation and protection from predators.
In the case of Great Horned Owls, West Nile Virus may be one of the main causes of their dwindling numbers. Like many raptors, owls are highly susceptible to this mosquito-borne virus which can cause serious neurological symptoms and even death.
Peterborough species totals
The species totals for the Peterborough count are as follows: Greater White-fronted Goose (1), Canada Goose (2,496), Canada/Graylag Goose (1), Trumpeter Swan (8), American Black Duck (11), Mallard (981), Ring-necked Duck (1), Bufflehead (11), Common Goldeneye (128), Hooded Merganser (23), Common Merganser (880), Ruffed Grouse (6), Wild Turkey (261), Double-crested Cormorant (1), Great Blue Heron (1), Northern Harrier (3), Sharp-shinned Hawk (5), Cooper’s Hawk (8), Bald Eagle (13), Red-tailed Hawk (56), Rough-legged Hawk (2), Ring-billed Gull (147), Herring Gull (217), Rock Pigeon (1,970), Mourning Dove (881), Eastern Screech-owl (7), Great Horned Owl (7), Barred Owl (2), Northern Saw-whet Owl (1), Belted Kingfisher (5), Red-bellied Woodpecker (44), Downy Woodpecker (114), Hairy Woodpecker (84), Northern Flicker (9), Pileated Woodpecker (16), American Kestrel (5), Merlin (3), Northern Shrike (10), Blue Jay (484), American Crow (423), Common Raven (79), Black-capped Chickadee (2,157), Red-breasted Nuthatch (34), White-breasted Nuthatch (147), Brown Creeper (18), Winter Wren (5), Golden-crowned Kinglet (32), Ruby-crowned Kinglet (1), Eastern Bluebird (6), Hermit Thrush (6), American Robin (569), European Starling (1,495), Cedar Waxwing (105), Snow Bunting (834), American Tree Sparrow (382), Dark-eyed Junco (741), White-throated Sparrow (6), White-crowned Sparrow (2), Song Sparrow (1), Northern Cardinal (298), Red-winged Blackbird (4), Brown-headed Cowbird (2), House Finch (58), Purple Finch (3), Red Crossbill (20), White-winged Crossbill (1), American Goldfinch (406), and House Sparrow (105).
Petroglyph Count summary
The 39th annual Petroglyph Christmas Bird Count took place on January 4. “Overall, it was fairly quiet day and we had to work hard to detect the birds. This meant making lots of pishing and squeaking sounds along with owl calls to draw the birds in,” said count organizer Colin Jones
The 37 participants recorded 33 species which is typical for the count. The number of individual birds tallied (2173), however, was lower than usual. “Although we had a good number of eagles, there were very few winter finches due to the overall lack of food such as tree seeds,” said Jones. Even so, most of the typical overwintering species like Blue Jays, Common Ravens and Golden-crowned Kinglets showed up in average numbers.
As for low tallies, Ruffed Grouse, Barred Owls, and Red-breasted Nuthatches were much scarcer than usual. No Black-backed Woodpeckers or Canada Jays were recorded. These were once annual species but have only showed up four times since 2009. With global heating, the Canada Jay’s range is retreating northward. It’s still unclear, however, how a changing climate is impacting Black-backed Woodpeckers.
Of particular interest this year was finding 3 Northern Cardinals – a new count high – coming to feeders on the southern edge of the count circle near Stoney Lake. Cardinals are continuing to expand their range northward.
Petroglyph species totals
The species totals are as follows: Common Merganser (2), Wild Turkey (38), Ruffed Grouse (7), Rock Pigeon (27), Mourning Dove (20), Golden Eagle (1), Northern Harrier (1), Bald Eagle (8), Red-tailed Hawk (3), Barred Owl (2), Downy Woodpecker (30), Hairy Woodpecker (44), Pileated Woodpecker (14), Northern Shrike (1), Blue Jay (265), American Crow (1), Common Raven (137), Black-capped Chickadee (1085), Golden-crowned Kinglet (43), White-breasted Nuthatch (142), Red-breasted Nuthatch (56), Brown Creeper (13), Winter Wren (1 on previous day), European Starling (20), American Robin (4), Cedar Waxwing (1), Evening Grosbeak (2), Red Crossbill (40), White-winged Crossbill (2), American Goldfinch (82), Snow Bunting (3), American Tree Sparrow (35), Dark-eyed Junco (38), Northern Cardinal (3).
Errata
Three errors appeared in last week’s column. The Summer Tanager was found by Helena Cymbaluk and the Harlequin Duck by Robin Morgan. The sightings of note that appear in the Peterborough Field Naturalists’ newsletter are compiled by Pam Martin.
