THE MOB

During last year's Christmas bird count, I saw a pair of crows
chasing and harrassing an adult bald eagle as it soared high over
the waters of Orwell Cove. On the 1977 Hillsborough Christmas
bird count, crows were observed pursuing and dive-bombing a rough-
legged hawk. When small birds gang up to harass larger ones,
the process is called mobbing and occurs in many species. In
spring, one may see a cloud of common grackles swirling around a
black object on a tree-top, which on closer examination, turns out
to be a crow. In a tern colony, any intruder (be it Gui), fox, .0r
human) is likely to be welcomed by a blitzkreig of screaming and
diving birds. Having felt terns rake through my hair, I can
personally attest to the effectiveness of mobbing as a strategy
to repulse unwanted guests.

Flocks of grackles or terns can successfully drive a predator
from their nesting area. However, not all cases of mobbing seem
to have a rational explanation and even when no advantage is
to be had, birds will continue their stereotyped mobbing of
avian predators in an almost automatic fashion. For example, a
healthy crow has little to fear from an eagle or hawk, but the
sight of either arouses a most yiolent reaction. Sparrows will
dive-bomb a stuffed owl until they are exhausted, and do so with
as much vigour as if their nests and young were actually threatened.

David Cairns
Universite Laval
Quebec, Quebec

CHRISTMAS BIRD COUNT REPORT 1977

For some of us Christmas just wouldn't be complete without a Christmas
Bird Count or two to round out the season. This year tne Hillsborough count
was held on Sunday December 18, a mild damp day wit!: a brisk wind blowing.
The day of the P.E.I. National Park count, Tuesday December 27, was bright
and sunny but tempered somewhat by chilly temperatures. Numbers for both counts
may have suffered from the cold stormy weather of earlier winter. Thirty-one
species were seen on the Hillsborough count and 30 during the National Park
count. Past counts ave averaged about 36 species each.
All those who participated ar> warmly thanked for helping to make the Christ-

mas Counts as successful as t!ey were. A summary of the results appears below.

species Hillsborough Count National Park Count
Great Cormorant 3
Black Duck 130 565
Green-winged Teal 4

Pintail 7
Common Goldeneye p 295
Barrow's Goldeneye 6
Oldsquaw 16 43
Black Scoter 4

Common Merganser 110 139
Red-breasted Merganser = 10
Sharp-shinned Hawk 2

Rough-legged Hawk 1

Ruffed Grouse 2 11
Ring-necked Pheasant pe 5
Gray Partridge 82

Glaucous Gull 1

Great Black-backed Gull 76 174
Herring Gull 293 696

Rock Dove i ae 123