The common loon (Gavia immer) is a large diving bird found across North America. Loons prefer clear lakes and slow-moving rivers in forested areas, where they can find plenty of fish to eat. During migration, loons may stop on lakes and ponds throughout the interior United States. This article explores whether loons can be found in the state of Illinois.
Loon Habitat in Illinois
Illinois has many lakes, rivers, and wetlands that could potentially provide habitat for loons during migration. However, most of the state lies in the prairie biome, which generally does not provide optimal loon habitat. Loons prefer boreal and northern forest habitats near clear, oligotrophic lakes. While Illinois has some forested areas, particularly in the south, much of the landscape is dominated by agriculture. This reduces the availability of high quality loon habitat. Still, loons have been documented in Illinois during migration.
Loon Migration Through Illinois
Loons that breed in Canada and the northern United States migrate south for the winter. Some loons may pass through Illinois on their way to wintering grounds along the Atlantic and Gulf Coasts. However, most loons take a more direct route over the Great Lakes rather than venturing deep into the interior of the continent. Banding studies show that loons breeding around the Great Lakes mainly winter along the Florida coasts. Loons from further north in Canada follow more interior migration routes through the Midwest. While not a major migration flyway for loons, there is evidence that some loons do stop in Illinois lakes and rivers each fall and spring.
Loon Sightings in Illinois
There are occasional confirmed sightings of loons in Illinois, primarily during spring and fall migration periods. Loon sightings have been recorded across much of the state. Some locations with reported loon sightings include:
- Chain O’Lakes State Park
- Carlyle Lake
- Clinton Lake
- Shelbyville Lake
- Lake Springfield
- Lake Bloomington
- Lake Decatur
- Lake Mattoon
- Lake Vermilion
These sightings indicate that while uncommon, loons do sometimes stop in Illinois lakes for rest and refueling during migration. The sightings are usually of single birds in spring or fall. There are no records of loons nesting or wintering in Illinois.
Rare Breeding Attempts in Illinois
There are a few records of loons unsuccessfully attempting to breed in Illinois. These rare breeding attempts likely involved migrating loons that stopped at an Illinois lake and tried to nest there before continuing their migration. Some evidence of this includes:
- In 1987, a pair of loons was observed nest building at Lake Shelbyville but did not produce eggs.
- In 1988, a pair of loons defended a territory and built a nest at Lake Springfield, but again no eggs were laid.
- In 1996, a pair of loons copulated at Rice Lake State Fish and Wildlife Area, but did not nest.
While intriguing, these incidents do not provide evidence of a sustained loon breeding population in Illinois. Rather, they show that migrating loons may occasionally and unsuccessfully attempt to breed during stopovers. Illinois lakes lack the fish populations, habitat, and isolation required for successful loon nesting.
Reasons Loons Are Rare in Illinois
Several factors explain the scarcity of loons in Illinois relative to more northern states:
- Illinois is south of the loon’s breeding range. Most loons nest across Canada, Alaska, and the northern U.S. like Minnesota, Wisconsin, and Michigan.
- Lack of boreal forest habitat. Illinois’ prairie and deciduous forests differ from the loon’s preferred evergreen forest habitat.
- Eutrophication of lakes. Fertilizer runoff has caused most Illinois lakes to become more eutrophic, with murkier water and denser fish populations. Loons prefer clear, oligotrophic lakes.
- Lack of isolation. Loons favor nesting on isolated lakes away from human disturbance and predator access. Illinois’ lakes are more numerous but smaller and less isolated than those further north.
- Warmer climate. Illinois is south of the loon’s usual summer range. Warmer temperatures may limit loon survival and reproduction.
In summary, Illinois generally lacks the habitat conditions and isolation that loons require for nesting. The state’s interior location also means it is not directly on the migration path for many loons. These factors explain why loon sightings in Illinois are relatively rare compared to states closer to their core breeding areas. A few migrating individuals may stop in Illinois, but sustaining a breeding population is unlikely.
Possibility of Future Loon Population Increases
While loon sightings are rare in Illinois today, there are a few reasons their numbers could increase in the future:
- Climate change – If climate change facilitates a northward range shift, loons may begin nesting at higher latitudes and have a more interior migration route through Illinois.
- Conservation – Habitat conservation efforts aimed at increasing water clarity in Illinois lakes could make them more suitable for loons.
- Nest platforms – Providing artificial nest platforms may allow occasionally visiting loons to attempt nesting.
- Population growth – Loon populations are increasing following bans of toxic lead fishing tackle. Higher numbers may lead more loons to be seen in Illinois during migration.
However, any increases in loon abundance would likely be very gradual due to the constraints of Illinois’ habitat and location. It is improbable that Illinois will become a major loon nesting state in the foreseeable future. Isolated nest attempts and migration sightings will probably continue to occur sporadically.
Summary
In summary, loons are occasionally observed in Illinois, especially during spring and fall migration periods. There have been a few instances of loons attempting to breed at Illinois lakes. However, Illinois’ interior location, lake ecology, and lack of boreal forest make it unsuitable habitat for a stable, breeding loon population. While sightings may increase modestly, loons are expected to remain uncommon and not nest in Illinois due to habitat constraints. The state will likely continue serving primarily as a migration stopover location rather than a breeding area for loons. Their characteristic calls will remain a rare treat for Illinois birders rather than a common summer experience.
Conclusion
To conclude, while loons are sometimes observed in Illinois during migration, the state falls outside the typical breeding range for these aquatic birds. Habitat limitations, including lack of boreal forest and isolated oligotrophic lakes, as well as Illinois’ southern location, prevent loons from establishing stable breeding populations. Occasional migrating loons may attempt to nest in Illinois but these attempts are unlikely to be successful. Conservation efforts could potentially allow incremental increases in loon sightings and rare breeding attempts in the state. However, loons will likely remain a rare sight in Illinois compared to more northern loon strongholds. They are unlikely to become a regular nesting species due to constraints of habitat and climate. Illinois will continue to provide occasional stopover spots for migrating loons rather than a new home for breeding pairs.
