For those who are interested, the discovery of a very high percentage of "blue" geese among the flock of 25,000 Snow Geese observed on the Sunday OFO field trip east of Ottawa is not unexpected. For the last few years, about 2-3 weeks after the main flight of Greater Snow Geese, there has been an influx of Lesser Snow Geese, the subspecies normally reported in very small numbers in parts of southern Ontario. The number of Lessers appearing in the east in spring now is high, several thousand, but still quite a bit less than the Greater Snow Geese we have come to expect each year.
For the Greater subspecies, the ratio of blue to white birds is actually very low (note: the geese hatch as either blue morph or white morph birds and remain that way) so when an exceptionally large concentration such as this is noted, they are unquestionably the Lesser subspecies. This dark and light pattern of Snow Goose flocks is a featured aspect of life on the Prairies during migration, where the birds are all Lesser Snow Geese. In the east, you normally have to look hard to spot blue morph birds among the Greaters. In concentrations like this, the blues stand out so they are very easy to count but there would certainly have been thousands of white morph Lesser Snow Geese among this large mixed flock of Greaters and Lessers. The white morph Lessers would be very difficult to isolate unless the flocks are pure. Given the number of blues reported by Bob Cermak on that trip and doing the math, it is not unreasonable to estimate that there may have been close to 10,000 Lesser Snow Geese within that large flock (there were about 6,500 blues). That would be the largest flock of Lessers ever recorded in the southern part of Ontario. Just five years ago there were only a small number of those birds being reported. This new migration pattern with the Lessers seems to be firming up. If anyone on that trip took photos of the mixed flock, please e-mail me privately. Brian Morin Cornwall _______________________________________________ ONTBIRDS is presented by the Ontario Field Ornithologists - the provincial birding organization. Send bird reports to [email protected] For information about ONTBIRDS visit http://www.ofo.ca/
