Common Loons are not known to be congenial hosts or particularly accommodating to visitors on their territories. In fact, they can be quite nasty at times, chasing and occasionally killing intruding loons or other waterbirds. These occurrences should not be frowned upon, since loons have a strong instinct to protect their chicks or themselves from potential predators or competitors for scarce food supplies.
At other times, however, loons can be quite social. Several CLLS volunteers have commented in letters or survey reports about seeing large flocks of loons on their lakes. These are not isolated incidents; reports of flocks of over 2,000 loons can be found in the literature, but groups of 3 to 20 loons are more common.
There are at least three possible explanations for the large numbers of loons observed on some lakes.
- Loons are most aggressive early in the breeding season; adults will sometimes visit other pairs to socialize later in the season, when hormone levels and aggressiveness are decreasing. I have seen these gatherings as early as July. Some researchers suspect that social gatherings later in the summer let loons slowly prepare for the presence of other loons during migration and on the wintering grounds.
- Groups of loons might also be part of a surplus, non-breeding population, either because they are young and have not gained a territory, were displaced from their territories, or lost their nests early in the season and didn't re-nest. These non-breeding loons will often group together.
- Loons also group together just before migrating, a behaviour known as staging. Staging tends to happen on lakes with good fish stocks in September or October.
The more I observe loons, the more I realize that, like humans, each is an individual. Therefore, there are probably as many reasons for groups of loons as there are groups of loons.
- Harry Vogel
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Canadian Lakes Loon Survey
Bird Studies Canada
P.O. Box 160, Port Rowan,
Ontario, Canada N0E 1M0
Tel: 519-586-3531 Fax: 519-586-3532
Questions about the CLLS? Please contact Kathy Jones
Email: aqsurvey@bsc-eoc.org
