Common loons are aquatic birds found across North America. They are known for their eerie, wavering calls which echo across lakes and ponds. But are common loons actually common? The answer is more complicated than it may seem. In this article, we’ll explore common loon populations, habitat requirements, migration patterns, and conservation status to gain a better understanding of how prevalent this iconic bird truly is.
What is the geographic range of the common loon?
Common loons breed across Canada and the northern United States. Their breeding range stretches as far west as Alaska, as far east as Greenland, and as far south as the northern tier of the contiguous United States. Minnesota, Wisconsin, Michigan, New York, Vermont, New Hampshire, and Maine have the largest common loon populations in the lower 48 states.
During the winter, common loons migrate from their inland freshwater breeding grounds to coastal waters. They winter along both the Atlantic and Pacific coasts, as far south as Baja California, the Gulf of Mexico, and the Outer Banks of North Carolina. So while common loons breed in the northern half of North America during the summer, they can be found across much of the continent during migration and winter.
What habitats do common loons require?
Common loons require freshwater lakes for breeding. They prefer large lakes (over 10 hectares) with clear water, which allows them to find the small fish that they feed on. Islands, coves, and bays are also ideal habitat features. These sheltered areas provide protection from wind and waves, safe sites for nests, and calm waters for chicks.
While loons spend spring and summer on inland lakes, they shift to more coastal habitats in fall and winter. Ocean bays, estuaries, large rivers, and lakes along migratory routes provide important stopover sites. Here, loons rest and feed to rebuild energy reserves during migration.
How many common loons are there?
Scientists estimate the total common loon population to be between 400,000 and 600,000 individuals. However, numbers vary greatly across different regions:
| Region | Estimated Population |
|---|---|
| Alaska | 10,000 – 30,000 |
| Canada | 300,000 – 400,000 |
| Contiguous United States | 70,000 |
Canada provides vast expanses of breeding habitat for common loons, resulting in the largest population numbers. Meanwhile, loons are less abundant in the contiguous U.S., where habitat loss and other threats have caused declines. Alaska likely holds tens of thousands of loons, but population surveys are limited in the state’s remote lakes.
So while common loon populations number in the hundreds of thousands, they are not evenly distributed across North America. Most loons breed in Canada, with smaller regional populations scattered across the northern U.S. and Alaska.
Are common loon populations increasing or decreasing?
After likely declines in the 19th century from hunting and egg harvesting, common loon populations rebounded during much of the 20th century. Bans on hunting and egg collecting, along with the creation of protected wilderness areas, allowed numbers to recover.
However, in recent decades, common loon populations have begun decreasing again in parts of their range. Threats such as shoreline development, lead poisoning, and climate change have impacted loons. The species is now listed as a Species of Special Concern in many U.S. states.
Some regions have seen sharper declines than others. For example, New England populations have dropped at an estimated 1.3% per year. Yet in Alaska and western Canada, numbers still appear stable. So common loon population trends have become mixed, with growth in some areas and concerning declines in others. Continued monitoring will be key to track how loon numbers hold up in the face of modern threats.
Why have common loon populations declined in places?
Common loons face a variety of threats across both their breeding and wintering grounds. Some of the major factors in their population declines include:
Habitat degradation – Shoreline development at breedings lakes removes nesting sites and vegetative cover. Pollution from roads, runoff, and industrial sources can degrade water quality. Acid rain has lowered pH levels in some lakes to the point where loons cannot breed.
Recreational use – Increased boat traffic and fishing disturbs nesting loons, which may abandon eggs or be separated from chicks. Shoreline recreation diminishes the isolation loons need.
Lead poisoning – Loons scavenge lead sinkers and jigs lost by anglers, ingesting the toxic metal. Even small amounts can poison and kill loons.
Climate change – Rising temperatures may threaten loons by reducing dissolved oxygen in lakes, shifting fish populations, and increasing nest flooding and erosion during storms.
Oil spills – Marine oil spills while on coastal wintering grounds can kill many loons at once, as loons’ feathers lose insulation when matted with oil.
Addressing these threats through habitat protection policies, lead tackle bans, boating restrictions, and climate change mitigation may be the key to reversing declining trends.
How do common loons migrate?
Common loons make one of the longest migration journeys of any North American bird. They nest on inland lakes in spring and summer, then fly hundreds or even over a thousand miles to reach coastal wintering grounds each fall.
Their migrations start in September and October, peaking later farther north. Loons fly singly or in loose flocks called “rafts”, at night when air conditions are calmest. They can fly 60+ mph for hundreds of miles nonstop over land and water.
Spring migration to breeding lakes is quicker, often completed in just a few long flights. Loons follow ancestral pathways passed down through generations, navigating by the stars and earth’s magnetic field. Many return to within just a few miles of the same breeding lakes year after year.
Banding studies by the U.S. Geological Survey have revealed the incredible distances common loons travel. One banded loon flew over 1,200 miles from Wisconsin to the Gulf of Mexico. Another made a 2,000 mile nonstop flight over just 4 days. These marathon migrations demonstrate the loon’s outstanding navigation abilities and endurance.
How do common loons mate and raise young?
Common loons have an intricate mating ritual to establish pair bonds and breeding territories. In April or May, loons return from the coasts to inland lakes. There they engage in elaborate courtship dances, splashing across the surface while “yodeling” to each other.
Once mated, pairs nest very close to shorelines on small islands, floating bogs, or muskrat houses to limit disturbance. The female lays 1-3 eggs in a shallow ground nest near water. Both parents incubate the eggs for 28-32 days, and transport the chicks to the water soon after hatching.
Loon chicks have black down and stripes for camouflage. They feed on small insects, fish and other prey provided by parents. By 12 weeks old, juveniles gain flight feathers and migrate south with their parents in the fall. The family bond dissolves on wintering grounds, where loons of all ages and pairings mix freely.
Most return north the following spring to breed again. Loons can live 30+ years, and may renest with the same lifelong mate each year. This pattern continues the propagation of common loon populations from one generation to the next.
Are common loons indicator species?
Common loons serve as indicator species due to their sensitivity to environmental conditions. Indicator species act as barometers of ecosystem health based on their population levels.
As large aquatic birds near the top of food webs, loons accumulate toxins and suffer when pollution degrades habitats. Declining loon numbers signal issues like mercury contamination, acid rain, lead poisoning, and shoreline development.
Loons also rely on healthy fish populations, so changes can suggest damaged fisheries. Since loons occupy both terrestrial and aquatic ecosystems during breeding, their numbers reflect the ecological health of lakes, rivers and coastlines alike.
By monitoring common loon populations and reproductive success, scientists gain valuable insights into freshwater quality, climate impacts, and aquatic food chain integrity. More than just a charismatic call in the night, the common loon is an important sentinel species for North American ecosystems.
How do common loons benefit lake ecosystems?
As top predators, common loons play an integral role in balancing lake food webs. Loons consume a wide variety of small fish, including minnows, suckers, sunfish, trout and perch. By selectively feeding on certain fast-reproducing fish species, loons prevent overpopulation and competition which could lead to fish die-offs.
Loons also concentrate nutrients like nitrogen and phosphorus from the fish they eat and excrete them in dissolved form through guano. This adds fertility to lake waters for algae and plants at the base of food chains. Lakes with loon populations see enhanced nutrient cycling.
Through their hunting habits and nutrient inputs, loons increase lake ecosystem biodiversity. Their presence is linked to improved water clarity, healthier fisheries and algal production. So by providing ecosystem services like food web stability and water enrichment, common loons contribute to overall lake function.
Are common loons territorial?
Common loons are highly territorial during the breeding season. Each mated pair establishes a breeding territory on a lake, defending the area from intrusion by other loons. Territories range from 25-150 acres depending on nesting habitat quality and food availability.
Loons advertise and protect territories using elaborate visual and vocal displays. Their “yodeling” call establishes ownership of a lake. Loon pairs perform synchronized territorial defense postures like the penguin dance and rush toward intruders while splashing water with wings and feet.
Physical confrontations do occur, as loons stab with sharp beaks and grasp with dagger-like webbed feet adapted for catching fast-moving prey. These adaptations make loons ferocious fighters when defending breeding areas.
Territorial behavior declines on wintering grounds, where loons congregate more tolerantly in nearshore waters. But defending exclusive nesting space on summer breeding lakes enables loons to reduce competition and maximize reproductive success.
How do people interact with common loons?
Common loons captivate people with their unique appearance and haunting calls, yet require space and isolation for successful breeding. This creates both appreciation and conflicts with humans across their range:
Birding – Loon watches and birding tours have become popular ecotourism activities. But boats must keep their distance from nesting areas during summer.
Lakeside recreation – Shoreline development and boating hamper nesting loons through disturbance, wake/wave erosion, and habitat loss.
Fishing tackle – Lead jigs and sinkers are ingested by loons, causing fatal lead poisoning. Tackle bans and takeback programs help reduce this threat.
Reservoirs – Artificial water level changes on dams can flood nests and separate parents from chicks.
Pollution – Loons accumulate mercury, pesticides and other toxins from acid rain, fuel emissions and industrial pollution.
With care and proper management, people can still enjoy loons by minimizing recreational impacts during breeding season and reducing environmental threats like lead, boating and shoreline development. Respectful coexistence maintains viable loon populations.
Conclusion
Common loons breed across Canada and the northern U.S. before migrating hundreds of miles to wintering coasts. While still widespread, populations have dropped in recent decades as threats like climate change, lead poisoning and habitat loss intensify.
Continued conservation efforts are needed to monitor numbers, safeguard key habitats, and mitigate environmental impacts. If sustained, common loons will continue gracing lakes with their primal calls, transporting wilderness spirits, and reminding us to tread gently on the water and land alike. The common loon remains an iconic symbol of northern wilderness yet also one intrinsically linked to, and reliant on, human stewardship.
