Photo by Lise Balthazar
The 18th Annual Lanark Highlands Christmas Bird count was highly successful this year. Held always on December 30 (except once due to icy conditions), the Count is centered on Watsons Corners and forms a circle within a 15 km radius. Sixty persons took part in the Count, 36 out in the field and 24 counting at their feeders. These 60 people counted 3 872 birds from 39 different species.
How does this compare with past results over 18 years? The record number of people counting totaled 62 in 2016; the record number of birds counted were 4 276 in 2010 and the record number of species listed was 42 in 2012. So, all in all, 2020 was a very good year.
One new species, a pied-billed grebe was listed for the first time. This bird was found in open water just up from the bridge at the foot of Dalhousie Lake. A record tying number of barred owls (6) and northern harriers(1) was tallied, tied with 2010 and 2009 respectively and this year the record number of trumpeter swans (16) was broken, up from (8) found in 2016. The Count leader this year was Jeff Mills, from Cedar Hill, and the feeder count leader was Lise Balthazar, Sheridan Rapids Road. Marcel Gauthier, Almonte, compiled and published the count figures. Congratulations to the participants of the Lanark Highlands Christmas Bird Count for this valuable contribution to North American citizen science work.
It was a German scientist in 1855, followed by others, who suggested birds were capable of detecting the earth’s magnetic field and using geomagnetism to guide them on migration. An early experimenter placed a small magnet on a bird’s wing prior to migration. The bird became totally disoriented and, on another note, adding to my series about bird migration theories (in the Lanark Era):
In the 1960’s, experimenters enlarged on the magnet trial by placing non-magnetic bars on several groups of homing pigeons and magnetic bars on others. They were taken a few hundred miles from home and released under heavy clouds to cut out the influence of the sun. The pigeons without magnets came home to their roost five out of seven times while those with magnets failed miserably. These studies showed magnetism influences bird behaviour; but does it help with migration?
In the 1980’s, at Cornell University, under strict experimental rules, scientist were able to prove, using Indigo buntings and Swainson’s thrushes, that birds at least initially orient themselves to the magnetic field when embarking on migration. It seems then, that the jury is still out on this intriguing aspect of how birds migrate. Next column, I’ll tell about migration theories using stars, sun and moon.
