Loons are aquatic birds found in North America. They can be found in freshwater lakes during the summer breeding season and along the coasts during migration and winter. Loons are excellent swimmers and divers, using their strong legs and webbed feet to propel themselves underwater as they search for food. But how exactly do these birds locate and catch their prey?
What do loons eat?
The diet of loons consists mainly of fish. They prefer small fish that are easy to swallow such as minnows, smelt, sticklebacks, and juvenile fish of other species. In addition to fish, loons may sometimes eat crustaceans, mollusks, aquatic insects, leeches, frogs, and aquatic plants.
Some of the common fish species eaten by loons include:
- Yellow perch
- Cisco
- Rainbow smelt
- Alewife
- Shiners
- Sculpin
- Sunfish
The specific species depends on the geographic location and habitat of the loon. For example, loons in coastal areas may prey more on schooling fish like herring and sand lance that are abundant near shorelines.
How do loons locate prey?
Loons have several adaptations that help them find food efficiently while swimming and diving underwater:
- Eyesight – Loons have excellent vision above and below the water’s surface. Their eyes are specially adapted to see clearly underwater.
- Neck twisting – Loons can twist their neck up to 270 degrees, allowing them to scan a wide area around them for potential prey while swimming.
- Diving ability – Loons are able to dive up to 200 feet deep in search of food, using their strong legs and webbed feet to propel themselves swiftly underwater.
- Bill shape – The long, pointed bill of the loon is ideally shaped for spearing and grasping slippery fish.
Using their keen sight, loons scan the water while swimming at the surface. Once they’ve pinpointed prey, they will quickly plunge their head underwater and swim downwards, using their feet like rudders to chase down food. Their streamlined bodies and stiff wings enable smooth dives in pursuit of fish.
How do loons catch prey underwater?
Loons employ a few different techniques to actually catch food once they’ve located it below the water’s surface:
- Spearing – When loons spot prey fish directly ahead, they spear the fish by striking with their sharp bills.
- Grasping – Loons can grasp small fish from the side in their bills.
- Plunging – From the air, loons may plummet directly down onto prey spotted near the water’s surface.
- Underwater chases – Loons commonly swim in pursuit of darting fish, catching them after a brief chase.
In addition their bill, loons may use their feet in underwater chases or to help manuever fish into a position where they can be caught in the bill. The combination of their streamlined bodies, good vision, and spearing beaks allows loons to effectively catch food beneath the water’s surface.
How much do loons eat?
An adult loon eats around 1 to 2 pounds of food per day on average. They need to consume a lot of fish to maintain their body heat and energy levels while swimming and diving in cold water environments.
Loons may eat up to 30% of their body weight daily. So a loon weighing 10 pounds could eat around 3 pounds of fish in a single day!
Loons feed most actively early in the morning and in the evening when fish tend to be nearer the water’s surface and thus easiest to catch.
Here’s an estimate of how much prey loons of different sizes may consume:
Loon Weight | Food Consumption |
---|---|
5 lbs | 0.5 – 1 lb |
10 lbs | 1 – 2 lbs |
15 lbs | 1.5 – 3 lbs |
Baby loon chicks rely on their parents to provide fish for their high-protein diet. Adult loons feed very small pieces of fish to newly hatched chicks.
How do loons swallow underwater prey?
Loons have a special anatomical adaptation that allows them to swallow food underwater without tilting their head back. At the back of their tongue, loons have a notch or grooved area that channels water out the sides of the bill while prey slides down the center to the esophagus.
This notch essentially acts as a one-way valve, enabling loons to swallow underwater. The groove in the tongue seals off the trachea (windpipe) so fish can be swallowed directly into the esophagus without water entering the respiratory system.
Some other waterbirds like grebes and cormorants have similar adaptations for swallowing prey while submerged without choking or inhaling water.
How do loons feed young chicks?
adult loons provide food for their chicks by carrying small fish back to the nest site. Loon parents hold the minnow-sized fish crosswise in their bill as they swim back to shore after fishing.
Once back at the nest, the adult loon tilts its head forward and drops the fish on the water in front of the chick. The semi-precocial baby chick will pick up the fish and swallow it whole.
Young chicks are fed very frequently, sometimes multiple times per hour! This provides the high protein intake needed for rapid growth and development in loon chicks.
Both the male and female parent loon share duties of scouting for food, diving to catch prey, and delivering it to the nest for the chicks. Good teamwork is essential to successfully raise loon young.
How has fishing impacted loons?
Some fishing practices and gear types have had negative impacts on loon populations through:
- Depletion of prey fish stocks
- Ingestion of lead sinkers and jigs
- Entanglement in fishing lines and nets
Overfishing can reduce the availability of small fish that loons rely on for food. Ingesting lead tackle is toxic to loons and a major cause of mortality in some areas.
However, certain restrictions on lead gear, sustainable fishing practices, and habitat protection efforts have helped reduce these impacts. Many groups work cooperatively with anglers to implement loon-safe fishing programs and policies.
How does weather affect loon foraging?
Weather conditions can influence the loon’s ability to find and catch prey in a few key ways:
- Wind – Strong winds create ripples and waves that make it harder for loons to see fish below the surface. Calm conditions allow for better visual hunting.
- Rain – Rainfalls stir up sediment that can cloud the water and impair the loon’s underwater vision.
- Water temperature – In colder water, fish become sluggish and easier for loons to catch. Heat waves may reduce feeding success.
- Ice cover – Ice blocks loons from accessing water where fish live. Loons must migrate away from frozen lakes.
Loons may be found feeding at all hours of the day and night. But inclement weather often causes them to rest on shore until conditions improve enough to effectively hunt for fish again.
How has climate change impacted loon foraging?
Climate change is altering loon habitat and food resources in a few key ways:
- Rising water temperatures may impact fish distribution and behavior
- Changing precipitation patterns affect water clarity which impacts hunting ability
- More frequent severe storms limit feeding opportunities
- Algal blooms from warming waters and runoff degradation impact water quality
- Increased flooding and drought events alter wetland hydrology
Researchers are still investigating the complex impacts of climate shifts on loon populations. Maintaining healthy lake ecosystems will provide resiliency for loons as environmental conditions continue to change.
Conclusion
Loons are highly adapted aquatic birds that use a variety of hunting techniques to catch fish and other prey from lakes and rivers. Their excellent vision, swift diving ability, and spear-like bills allow them to deftly snatch food from beneath the water’s surface. Adult loons need to consume large amounts of fish daily and they diligently feed small fish to their chicks. Conservation of wetland habitats and management of responsible fishing practices are key to ensuring loons continue to thrive and feed successfully into the future.