GREATER FUNDY ECOSYSTEM RESEARCH PROJECT
UNB Faculty of Forestry and Environmental Management
State of the Greater Fundy Ecosystem
Common Loon on Wolfe Lake
Douglas Clay and Heather Clay
Fundy National Park
P.O. Box 40, Alma, N.B. E0A 1B0
Common Loons and chicks on Wolfe Lake,
Common Loon (Gavia immer) is a species sensitive to a variety of human disturbance (Titus and van Druff, 1981). Shrinking breeding ranges and declining numbers of Common Loon appear to be more related to recreational use of loon habitat rather than on lake acidification (Strong et al., 1987; Parker, 1988).
Wolfe Lake is located on the headwaters of the East Branch of the Point Wolfe River. It is a relatively unproductive oligotrophic body of water with low nutrient and suspended solid concentrations and because of this it is considered to be marginal habitat for Common Loon. The loons on Wolfe Lake are thought to supplement their diets from other lakes in the area. There appears to be sufficient fish and other organisms available on Wolfe Lake and other nearby lakes to support two adult loons and two young.
The Common Loon was first recorded at Wolfe Lake in 1965. Although loons prefer lakes that are greater than 50 ha., they will nest on smaller lakes - such as the 22 ha. sized Wolfe Lake - if the lake contains a suitable island that can be used for nesting (Masse, 1991). Wolfe Lake contains two such islands. The first pair of loons and a juvenile were recorded on Wolfe Lake in 1976. Confirmed nesting has taken place here from 1989 to 1996, perhaps by the same pair of loons. Common Loons have been sighted on Bennett Lake and Tracey Lake - two other larger-sized lakes in the park - but none have become established on these lakes possibly due to higher recreational use. It is thought that transient loons coming in from outside the park may be seeking temporary refuge on lakes within the National Park due to external lakes coming under increased human pressure. The presence of visiting loons indicates a need to monitor surrounding lakes in the Greater Fundy Ecosystem.
A loon monitoring program was initiated by the park in 1989. The objective of the program was to identify the factors that influence the reproductive success of the birds and to compare the findings with loon studies done in other parts of North America. Weighing and banding of the birds was done in 1995 and 1996 with the help of the Canadian Wildlife Service (CWS). The birds that were banded in 1995 were found to be the same ones which returned to the lake in 1996.
Present-day human disturbances on the lake are limited to canoeing, non-motorized boating, a nearby campground, a day-use picnic area and a boat launch. Nesting loons tend to be more severly affected by canoes and fishing boats which tend to travel close to the shore than they are by motor boats which tend to travel through the centre of a lake (McIntyre, 1975). Campsite use at the lake has dropped substantially since the ending of a Brook Trout stocking program in 1980. A boat rental operation also ceased at that time. There has been no active management of the aquatic resources of the lake since 1980.
Although visitor pressures have been reduced over the years, conflicts can still occur. The period of loon courtship behavior coincides with the time of the Victoria Day weekend in late May. As such, the campgrounds are usually heavily used and the greater possibility exists for disturbance of the birds. As well, the nesting and hatching periods coincide with Canada Day and American Independence Day holidays in July. Restrictions on visitor activities on the lake will be necessary to ensure that critical stages in the reproduction cycle of loons are respected.
|To help the loons on Wolfe Lake during the nesting and hatching period (late May - mid July) efforts were made to close sections of the lake to recreational fishing by boat. In 1989, lines and buoys were used to close off the nesting area. However, these tended to attract curious visitors to the nesting site and caused stress to the birds. In 1994, notices were put up at the information centre and boat launch to inform visitors about the nesting loons. However, these notices tended to be ignored. In 1996, the decision was made to close the lake entirely to boating and fishing.
Chick survival on Wolfe Lake has been 65% on average over the past eight years. In total, 11 young survived from a potential of 17 eggs. The reasons for nest failure have varied. In 1992, a nest was found abandoned with one broken egg and a dead chick nearby. The egg was probably damaged by a predator, possibly a raven. The parents are thought to have abandoned the nest due to disturbances from fishermen and canoe traffic. In 1993, the parents abandoned a nest on the lake's smaller island for unknown reasons and re-nested on the larger island. Nesting success can also be affected by fluctuating water levels. Water levels on Wolfe Lake can be lowered by droughts and by breaches in the slowly deteriorating dam. Sudden water fluctuations from breaches and subsequent repairs in the dam can lead to nest failure. As such, it is important to maintain the dam, especially during the nesting period.
The reproductive success of loons on Wolfe Lake has been quite good. Over the past eight years, only one chick out of 12 has died within the first few days of hatching. Reproductive success, which is defined as the number of fledged young per breeding pair per year, was 1.4 with 92% of the young fledged. In comparison, the average reproductive success of loons at Grafton Lake in Kejimkujik National Park, N.S., was 0.5 (Benjamin and Kerekes, 1993). The average for New Brunswick and Nova Scotia reported by the Canadian Lakes Loon Survey is 0.64 and 0.74 respectively (Vogel, 1993).
Other threats to the Common Loon population arise from fishing activities on the lake. Nesting sites can be directly disturbed by fishermen along the shore. As well, fishermen frequently use lead sinkers and nylon fishing lines. When ingested by birds, lead sinkers can cause lead poisoning (Pokras and Chafel, 1992; Ferns, 1994; Sam and Boates, 1993; Vogel, 1994; Thomas and Twiss, 1994). Fishing lines can cause entanglement. In August 1995, a female was observed to have fishing line wrapped around her beak and tongue (Greer, 1995). This prevented her from feeding herself and her chicks. After considerable effort by National Parks staff and CWS biologists, the female was captured and the fishing line removed.
The presence and survival of Common Loons is a useful indicator of the ecosystem integrity of a lake (Anon, 1994). Common Loons feed on fish which are bioaccumulators of heavy metals, such as mercury, and pesticides that may be found in the water. Many loons die from the effects of these toxic materials when they are away from the land in the open ocean (Spitzer, 1995)
Several recommendations have been put forth for protecting the Common Loons on Wolfe Lake. Some of these were implemented in the summer of 1996:
Wolfe Lake should be closed to boating traffic from May 15 to July 15 each year to ensure freedom from nesting disturbance.
Fishing should be discontinued in Wolfe Lake. The nutrient requirements of a pair of breeding loons does not leave any surplus fish resource for human harvest in the National Park.
Sudden unnatural water level changes should be prevented by maintaining (repairing) the dam at the southern end of Wolfe Lake.
Anadromous and catadromous species should be encouraged to return to the lake by diversion of the outflow via a stream (spillway) around the dam wall. Currently the dam wall prevents movement since outflow is a slow seepage through the dam wall. A spillway would allow eels and brook char freedom of movement up the East Branch of the Point Wolfe River to Wolfe Lake. This should increase the apparent total fish productivity of the lake.
Wherever fishing is to continue in the National Park, then non-toxic sinkers must be substituted for the lethal lead type. This should be the case for all fish waters of the park.
Increased public awareness and education is important to promote the conservation of Common Loons. Displays, interpretive events, films, leaflets and viewing areas could all contribute to promoting awareness and enhance the visitor experience.
Co-operative partners should be developed to maintain and monitor surrounding lakes as staging and feeding areas.
The high degree of interaction of the many resources of Wolfe Lake requires an ecosystem management plan.
An investigation should be conducted on the adjacent McManus brook to identify if it flowed into Wolfe Lake before the adjacent gravel quarry and highway was developed.
Clay, D. and H. Clay. 1996. Update of the Status of the Common Loon (Gavia immer) on Wolfe Lake, a small oligotrophic lake. Research Notes of Fundy National Park. No. FUN/96-07. Alma, NB.
Clay, D. and H. Clay. 1997. Reproductive success of the Common Loon, Gavia immer, on a small oligotrophic lake in eastern Canada. Canadian Field-Naturalist 111(4):586-590
Clay, H and D. Clay. n.d. Winter distribution of the Common Loon (Gavia immer) and Red-throated Loon (Gavia stellata) in the Bay of Fundy. Unpublished paper on file at Fundy National Park. Alma, N.B.
Information provided by:
Dr. Graham Forbes
Faculty of Forestry and Environmental Management at UNB
Last Update: May 7, 1998
This document: http://www.unb.ca/web/forestry/centers/cwru/soe/loon1.htm