La Mauricie National Park of Canada
The Common Loon Under Strict Surveillance
A Common Loon in its nest © Parks Canada/Jacques Pleau
Each summer, tens of thousands of visitors come to La Mauricie National Park lakes to spend time canoeing or fishing. Their presence, as well as the impact of acid rain, affects the common loon.
Since 1987, the Conservation Service has been keeping a close eye on the common loon population. This bird is a good indicator of the quality of aquatic ecosystems. This is why, each year, the biologists carry out surveys in order to confirm the presence of loons and locate their nests. The data gathered allows the park authorities to monitor the population and its rate of reproduction, to assess the impact of visitors on the area and to identify protective measures that may be taken. Evaluations are also carried out on the effects of atmospheric pollutants on aquatic ecosystems.
A Fragile Population
Studies have shown that if the young birds are disturbed too often, they may stop feeding, fall sick or be abandoned by their parents. Another problem is fishing: a number of birds have been fatally wounded by fish hooks, or poisoned by swallowing lead sinkers.
Atmospheric pollutants also have an impact on the loon population. Acid rain diminishes the number of fish in the lakes, which compromises loon reproduction. Did you know that a breeding pair and two fledglings ingest 463 kg of small fish over one season?
Maintaining Favourable Conditions
A public awareness program has been developed. Island stopovers by canoeists have been prohibited, since that is where the loons nest. During the nesting period, access to certain lakes has also been prohibited and the number of visitors has been limited at others. Warning signs have also been installed near the islands. Moreover, rehabilitation work has been carried out on the islands and artificial nesting islets have been created. Since 1997, the use of lead sinkers for fishing has been banned.
Recently, other measures have been added to the study: blood samples were taken from 17 loons to assess their level of mercury contamination. Preliminary results indicate the park loons are as contaminated as those found elsewhere in Eastern Canada.
The results of research carried out in the park are shared with other organizations within the framework of a national loon surveillance program. In brief, everything has been done to ensure that the score of breeding pairs that nest on the park lakes may find appropriate living and breeding conditions.
The Common Loon: Some Results Over the Years
| Years |
Pairs inventoried on the territory (1) |
Breeding pairs |
Fledglings (2) |
| 1987 |
18 |
13 |
16 |
| 1988 |
20 |
20 |
20 |
| 1989 |
25 |
14 |
13 |
| 1990 |
18 |
14 |
14 |
| 1991 |
28 |
13 |
19 |
| 1992 |
25 |
14 |
13 |
| 1993 |
24 |
13 |
14 |
| 1994 |
26 |
11 |
12 |
| 1995 |
32 |
12 |
11 |
| 1996 |
30 |
17 |
6 |
| 1997 |
27 |
16 |
17 |
| 1998 |
27 |
10 |
7 |
| 1999 |
23 |
13 |
14 |
| 2000 |
25 |
13 |
9 |
| 2001 |
25 |
19 |
14 |
| 2002 |
31 |
18 |
8 |
- Many pairs inventoried in June do not breed.
- Between 30% and 50% of the young birds die prior to the fledging period because of predators, under nourishment and sickness.
- The low breeding rates in 1996 and 1998 can be explained by the flooding of many nests, following the heavy June rains.