Common Loon

The Common Loon is a native bird of the North American Continent. Although records of the common loon have been around for 20 to 30 million years, the emergence of the loon in British Columbia only dates back 121 years. As Canada has more lakes than anywhere else in the world, 95% of common loons breeding in the world are found in Canada. Common Loons are characterized by a streamlined body with a dense coat of waterproof feathers that help with swimming and diving. It is listed under the federal Endangered Species Act in the United States and the Committee on the Status of Endangered Wildlife in Canada, both of which designate the species as “not at risk”. The species is also ranked globally as fairly secure by the Nature Conservancy. Although not ranked as in danger of extinction, reports in North America state declines in loon populations. In addition, it is a species of conservation concern in BC. Acidification of lakes, heavy metal contamination in rivers and lakes, human encroachment and impacts of climate change are a few reasons why the common loon is becoming more and more vulnerable and threatened by the human world. Efforts including fish stocking programmes that first attracted loons to the area are now being reused in an attempt to repopulate areas across BC and increase loon populations.

World Range and Occurrence

Annual historic and current populations are accurately documented due to lack of quantitative statistics and research studies. Common loons usually breed on fresh-water lakes throughout the boreal forest region, ranging from North-central Alaska, east across northern Canada and South to the northern United States. Loons primarily spend winter along the coasts of the Pacific and Atlantic, but are also found in Greenland, Iceland and the Atlantic coast of Great Britain. Although traditional in winter, loons are frequent visitors through spring to autumn across the entire province of BC. Annual occurrence statistics show the main period of residency for common loons in British Columbia along the coast is during winter months, between December and February, and in summer months population numbers are significantly lower. For BC interior, the opposite is seen, as peak residency rates occur in summer, and winter holding the lowest population numbers for the entire year. It is estimated that 30% of the entire North American common loon population winters on the BC Pacific coast. Birds arrive from breeding grounds in Alaska, Northwest Territories, Yukon, Washington and Montana. Most of the BC populations migrate from the interior freshwater breeding sites in winter to coastal locations. Hundreds of loons have been observed gathering at sites off the mouth of the Fraser River, off Roberts Bank and throughout the Canadian Gulf. The two largest flocks in BC reported 200 birds off Tsawwassen ferry jetty on 1st September 1990 and 187 birds in Deep Bay on Vancouver Island on 21st March 1967. Occasional large flocks are reported across the province but are assumed to be due to weather conditions or food supply.


Common loons tend to begin breeding at the age of six on average. Breeding does not occur earlier than four years old, but may be as late as eleven years old. Courtship involves a series of head turning, bill pointing and diving. Copulation takes place on land, either on the shore, in a nest or semi-solid surfaces such as grassy islets. Loons arrive at breeding sites a few days after the ice in lakes and rivers begins melting. Typically, males arrive at breeding territories a few days earlier than females. Arrival times also vary with elevation and latitude. In BC, loons mainly breed on clear, quiet, large to small freshwater lakes in open and forested locations. Areas of low productivity, clear waters with low nutrient levels, sparse plant life and low fish production are preferred breeding grounds. In addition, loons prefer to nest along clear, slow-moving rivers with deeply indented bays and large marshes, and less frequently on open, wooded swamps with fallen branches. Approximately 1.75 ha or 15% take up nurseries in loon territories. Following copulation, nests are constructed by both parents on the ground close to water or on mats of vegetation over water and take around a week to complete. Nests are normally constructed with twigs, leaves, driftwood, aquatic weeds, mosses, small stones, coniferous and deciduous seed-casings and branches. Human materials including plastic combs, string, paper and plastics have also been found in nests. Loons have adopted a monogamous breeding strategy and most pairs spend the breeding season together but are independent in winter. When pairs breed together every year, high fidelity to nest sites is observed. In southern areas of BC, pairs sometimes spend up to five weeks on breeding lakes before nesting and breeding begins. In the northern areas of BC, this period may be reduced to a couple of weeks. The full breeding period in BC extends for almost 6 months, from April to September, including events such as egg-laying to first flight of chicks. Peak egg-laying occurs in late May to early June and hatching occurs during the last week of June to the end of July. New chicks take first flight and depart the natal lake in late September through to early November. The full breeding period in BC spans a total of 235 days from 28th March to 17th November. Both parents share incubation duties but normally lasts from 27 to 31 days. Chicks hatch asynchronously and breaking through the shell can sometimes take up to 52 hours but usually occurs between 8 and 15 hours. They are born a sooty black colour with white bellies and when they are about three weeks old they change to a brown-gray colour. By eight weeks, chicks are fully feathered and begin exercising their wings. Chicks leave the nest within a day but remain dependent on parents for food for some weeks. By eleven weeks old, the young can capture about half of their own food and first flight takes place around this time too. Common loon lifespans are from 20 to 30 years, with the oldest banded bird from North America reaching 23 years old.

Habitat and Migration

Common loons’ primary habitats are along coastal environments, on marine bays, inlets, channels, harbours, estuaries and other shallow areas. In BC interior, they are typically found in large freshwater lakes, marshes and slow-moving rivers and backwaters. Loons migrate annually to reach breeding grounds. Migration occurs during the day and often reaches altitudes of 2,500m when travelling through mountainous regions, e.g. Pine Pass, to reach BC interior or coastal areas. In the BC interior, loons are a common spring and autumn migrant with peak residency in summer and small numbers spending the winter here. Along the coast, loons are also spring and autumn migrants, however residency rates peak during winter instead of summer, the highest numbers in summer along the coast occur around the Queen Charlotte Islands. The average arrival of loons following melting of the ice on the lake was approximately 14.8 days and is usually around 10th April. Average departure date from lakes in BC is 10th November. The length of migrated loons in BC ranges from 149 days to 266 days with shorter residency rates the higher the elevation. As the climate warms, it’s observed that loons are shifting their winter dependency on coastal regions to interior lakes that remain ice-free.

Feeding and Diet

Adaptations allowing loons to dive and feed in marine environments mean their diet consists solely of fish. Studies in North America show that loons prefer prey with small heads, soft scales, slender bodies and no spines. They catch and feed on small prey whilst underwater. A study in the central interior of BC revealed adult loons successfully raising young chicks in lakes with no fish, showing the birds to also feed on mollusks, caddis flies, amphipods and dragonfly nymphs.

Mortality Rates

Death rates of the common loon are mostly unreported, therefore statistics are misleading as more reports does not necessarily show more deaths, only more deaths reported. Of 887 deaths reported, 31% were due to museum or private collecting, 11.6% indiscriminate shooting, 9.9% were found washed ashore in marine environments, 9.0% found dead with unknown causes, 4.7% were the result of predation of chicks and/or small young. The rest of deaths were determined to be the cause of fishing, bird and mammal predation of eggs and small young, oil spills, inclement weather, disease, habitat loss, ingestion of plastics, road kill and frozen in ice.

Threats to Loons in British Columbia

The most impacting effect to loons in BC is the cause of human influences that affect migrating, breeding and wintering patterns. Shooting, fishing, shoreline development, nest trampling, recreational uses of lakes, contaminants, museum and private collecting, oil spills, creation of dams, diseases and acid rain etc., all contribute to the negative influences impacting loons. 26% of 86 carcasses brought to the Royal British Columbia Museum from 1973 to 1983 contained lead shot or bullet wounds and shooting is still a problem in small lakes, and a greater concern in lakes that undergo fish-stocking programmes. Loons are also at threat in fresh-water and marine environments from fishing nets, accidental entanglement in nets results in many loon deaths and fishing activity remains a serious threat to the loon populations in BC, however most deaths go unreported. Furthermore, development of human structures over the past 20 years such as resorts, campgrounds, recreational use around lakes and coastal areas negatively impact loons in terms of breeding and distribution patterns. 80% of a 42km stretch on a lake shoreline was altered by housing, cottages, parks and swimming beaches, degrading loon habitats and breeding sites around fresh-water environments. In addition, recreational use of lakes in BC negatively affect loons, for example jet skis and motor boats using lakes in summer have washed away nests and eggs situated on the shoreline. Canoeing has also resulted in predation of young chicks from Bald Eagles after this recreational sport has separated young from their parents. Contamination of fresh-water sources from organochlorines, heavy metals and mercury has resulted in the incidence of egg-shell thinning, and elevated mercury levels is possible to have influenced reproductive capacity in loons.

Conservation and Management

The primary concern for conservation of common loons in BC is due to indirect (e.g. oil spills, chemical contamination, acid rain etc.) and direct (e.g. habitat degradation, shooting, disturbance etc.) issues that arise from human influence. Breeding numbers and patterns have been reduced over many years due to urbanization, habitat degradation and human disturbance around southern Vancouver Island and the Lower Mainland. Changing attitudes of local residents in the area is encouraging a more protected future for common loons. Development of non-game programs to include all species in conservation and management activities, which will not only protect common loons but the fish they feed on too is focused on improving the entire ecosystem and will benefit a variety of species under threat from human activity. A greater focus on education will also increase the likelihood of protecting the common loon species, development of conservation programs for the public education through the media, naturalist and sportsmen clubs and school curricula will engage with humans that pose the most threat to the species to connect with the environment and prevent further decline in species population numbers and distribution patterns. Furthermore, management decisions are suggested to be based on ecological factors rather than political boundaries, taking a higher level of consideration for the wildlife instead of human influences. For example, sites considered most vulnerable should be identified for sensitive periods during the birds annual cycle, these areas may include specific locations where large numbers of loons aggregate in migration and winter and thus become susceptible to oil and chemical spills and human disturbance and harassment. Some areas may require protection seasonally. Christmas Bird Counts were established to gather data about population sizes of loons and annual distribution ranges across BC. Meticulous monitoring and research of loon populations and distribution across the province was conducted in order to reach the ultimate goal of producing a self-sustainable common loon population with a minimal level of threat from human activities. High resolution monitoring of breeding populations and continued improvement and refinement of survey efforts will update current known breeding locations and migration patterns, ultimately improving management strategies to avoid and restrict human influence to protect the species from human interaction. Furthermore, research into whether human influences such as contamination, oil spills and other localized stressors affect populations in BC. Education of the local public through media sources such as the internet, updating fishing regulations, and information of threats to common loons in local schools are all planned to manage the protection of loons in the rural interior BC. Policies including the North American Waterfowl Management Plan, Shorebird Conservation Plan, United Nations Environment Program’s Global Mercury Assessment among others are concerned with species protection of wildlife in North America and Canada, and BC on a local scale, focusing efforts on regulating anthropogenic air emissions and mercury and lead content in fresh-water sources. They also work to continue to prevent human influence on the common loon species including preventing oil spills by identifying sensitive areas and updating regulations to restrict oil tankers travelling near these areas. Furthermore, continuous updates to the loon database throughout BC contributes to known knowledge of the species through sightings, published and unpublished reports, wildlife surveys, field notes etc. Improved knowledge contributes towards the development of conservation projects that protect the common loon species throughout the BC province.

  • Source R. Wayne Campbell, Michael I. Preston, Linda M. Van Damme, David C. Evers, Anna Roberts, Kris Andrews. June 2008. Wildlife Afield Journal. Wildlife data centre Feature species - Common Loon. Availlable at : [Accessed 03/2021].