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DVOC Field Trip Report
by Keith Russell
January 10, 2004 (Saturday)
Philadelphia Census - Keith Russell - Coordinator
The 18th annual Philadelphia Mid-Winter Bird Census was held on Saturday January 10th, a bitterly cold day on which the official temperature only reached a high of 16 during the afternoon hours and hit a low of 4 during the early morning (falling even lower in outlying areas). It was the coldest day in Philadelphia since February 5, 1996, and the coldest day on which the census has been held to date. Despite the frigid conditions 59 observers in 29 parties recorded 96 species, which tied our third highest species total ever.
Although temperatures were unusually low, conditions were otherwise pleasant for birding with partly sunny skies during the morning, mostly sunny skies during the afternoon, and generally light winds throughout the day. There was no snow cover, but because of the cold temperatures, which had only arrived in the region on January 7, all areas of standing water were 98-100% frozen, while rivers and streams had variable amounts of ice ranging from 0% on the Delaware to 85% ice cover on sluggish streams.
Prior to the freeze bird diversity in the Philadelphia area had been high this winter. In addition to the usual species a number of half hardy species and several invasive species that do not appear every winter were present. Because of the freeze however, several species of waterbirds were missed on census day while several others were recorded in lower than average numbers. The cold also reduced the activity levels of most bird species making it difficult to even find common birds like starlings in some areas. Given these challenges I would like to give special thanks to everyone who participated this year, especially the owling teams that were out when it was coldest (including the Williams team, Bilheimer team, Russell team, and especially the Belford team which found 12 Screech-Owls). That 96 species were recorded under such difficult conditions is a testament to your dedication, perseverance, and skill, and the information gathered will be helpful in understanding how birds in our region are affected by such extreme conditions.
While no new species were found this year several rare species were recorded. These included a Pine Warbler at Roosevelt Park that was discovered by Stijn Brand and Rich Horwitz (2nd record), 35 Red-breasted Mergansers that were seen by the Belford team flying over the upper Wissahickon Creek of all places (3rd record), and a Long-eared Owl in the Upper Wissahickon found by Kate Somerville and myself (3rd record). Additionally, David Cutler found an immature Iceland Gull at a trash transfer station along the Delaware, as well as 15 Common Redpolls which briefly landed in a tree at Penn Treaty Park (both 4th records).
Several species were recorded at record high numbers, perhaps in part because there had been numerous periods of above average temperatures throughout the autumn and early winter. These included 44 Double-crested Cormorants - which have never previously outnumbered Great Cormorants, 43 Great Blue Herons - 29 of which were observed huddled together on the ice at the J. Heinz refuge, 1337 Mallards - an always numerous species which may have become concentrated at fewer locations this year by the freeze, 3 Red-shouldered Hawks - a bird rarely recorded as high as two, and often missed, 42 Hairy Woodpeckers - whose normal numbers range from 20-30, 126 American Tree Sparrows, 18 White-crowned Sparrows -which were found by a record three different parties, and 1754 Dark-eyed Juncos - a species which ranked fifth (unusually high) in numbers this year after European Starling (7705), Canada Goose (5319), Ring-billed Gull (3401), and White-throated Sparrow (1953). Field Sparrows and Savannah Sparrows were also recorded in larger than average numbers, but Swamp Sparrows were recorded at a record low, perhaps because so much of their habitat has recently been lost. Relatively high totals were also recorded for Mute Swan, Northern Shoveler, Common Merganser, American Robin, and Brown Creeper. Reasons for some of these highs are not entirely clear but the mergansers (most of which were found on the Delaware and Schuylkill rivers) always appear in large numbers during very cold years when they have been forced from other wintering areas by ice. The appearance of Eastern Phoebe (Hetzel team), Brown Thrasher (McGovern), Chipping Sparrow (Binns, Filemyr, Murphy), 3 Great Egrets (McGovern, Miller), 4 Palm Warblers (Wiedener), and larger than average numbers of Gray Catbirds may have also be due in part to the many mild periods that occurred during the autumn and early winter.
Several other interesting trends were also evident in this year’s results. Bald Eagle, Merlin, and Lesser Black-backed Gull, which were all rare 10 years ago, continued their pattern of being recorded regularly since the mid 1990s, further confirming that their regional populations have increased. Northern Goshawk (Walters) was also observed for the 3rd time in 4 years. On the down side, in addition to Swamp Sparrow, record lows were recorded for Canvasback, Northern Harrier, American Kestrel, Northern Flicker, American Crow, Carolina Chickadee, and Cedar Waxwing, and near record lows were recorded for Ring-necked Pheasant, Herring Gull, Mourning Dove, Fish Crow, Tufted Titmouse, and House Finch. While we know that avian conjunctivitis has been responsible for lowering House Finch numbers over the last decade, West Nile Virus has been implicated in the deaths of many crows over the last few years, and habitat loss has reduced the number of field birds like pheasants, it is unclear whether the cold or other factors caused numerous species like flickers, chickadees, and titmice to be so scarce. Even more astounding was the 95% reduction in the number of crows of both species from their usual numbers. Both species had remained abundant through last winter despite the fact that many individuals were known to be infected with West Nile Virus over the last few years. Species normally recorded that were missed this year include Black-crowned Night-Heron, Black Vulture, American Wigeon, Common Goldeneye, Eastern Bluebird, and Brown-headed Cowbird. Species observed the day before the census included 6 American Wigeon at Roosevelt Park and a flock of Wild Turkeys in the upper Pennypack.
I would like to take the opportunity to express
special thanks to Doris McGovern and Kate Somerville for their assistance.
Special congratulations are also due to David Cutler (who has participated
in the census annually since its inception in 1987) for being made an
honorary member of the Delaware Valley Ornithological Club. It’s
a long overdue honor that David richly deserves.
Common Loon 1