Brown pelicans are large seabirds known for their enormous throat pouches that they use to scoop up fish and other prey. They are found in coastal areas and estuaries in the Americas, and are skillful hunters that have adapted unique methods for catching their food.
Brown pelicans primarily feed on small fish that swim near the water’s surface, such as anchovies, herring, sardines, and mackerel. When hunting, they fly low over the ocean and scan the water for signs of fish activity. Once they spot prey, they fold their wings back and dive headfirst into the water with a large splash. The impact often stuns small fish, making them easier to catch.
How do brown pelicans locate prey?
Brown pelicans have extremely keen eyesight that helps them locate fish swirling in the water. As they fly over the ocean, they can spot a single silvery fish from heights of over 65 feet. The contrast of the fish against the dark ocean background makes them easier to see from above. Their eyes can rapidly focus underwater as well, allowing them to still track prey after diving in.
In addition to eyesight, brown pelicans may use clues such as feeding seabirds to find large schools of fish. By following other avian predators like terns, seabirds, and gulls, they can increase their chances of discovering bountiful hunting grounds.
How does a brown pelican’s body help it catch fish?
Brown pelicans have bodies uniquely adapted for plunge diving. Their streamlined shape and light, rigid skeleton helps them slice smoothly into the water without injury. Air sacs under their skin cushion the impact, while a third eyelid protects their eyes.
Their most distinctive adaptation is their stretchy throat pouch. This elastic pouch can expand to hold up to three gallons of water and fish. Right before impact, they open their bill and expand the pouch to its maximum size. Once underwater, they snap their bill shut to scoop up any prey.
Large webbed feet equipped with rough bumps on the toes act as natural aquatic rudders, allowing them to swiftly change direction underwater while spearing fish into their pouch. Their feet also serve as paddles to propel them back up to the surface.
What is the step-by-step process for catching fish?
Here is the typical sequence brown pelicans use to catch their prey:
- Search and locate – The brown pelican flies over open water searching for signs of fish activity. It may also follow feeding flocks.
- Dive and plunge – Once fish are spotted, the pelican folds back its wings and dive-bombs headfirst into the water with a big splash, stunning small fish.
- Scoop and capture – Right before hitting the water, the pelican fully expands its throat pouch and snaps its bill to engulf fish and water.
- Maneuver underwater – Powerful webbed feet help the submerged pelican swiftly change direction and corral fish into its pouch.
- Surface and drain – The pelican paddles back up and lifts its bill to drain out the seawater, while tilting its head back to keep captured fish trapped inside its elastic throat pouch.
This technique of high-speed plunge diving allows brown pelicans to surprise and disorient schools of fish, making them easier to scoop up in large numbers. It takes great precision and skill to dip only their throat pouches in the water without submerging completely.
How much prey can a brown pelican catch at one time?
Brown pelicans can fit up to 3 gallons worth of fish and water in their throat pouches. This allows them to catch an impressive amount of prey in one hunting dive. They typically catch 4-5 average-sized fish at a time, depending on the size and species. Their pouches have been known to hold up to 30-40 anchovies in a single scoop.
After draining out the water, adult brown pelicans can hold up to 30 lbs of fish total in their pouches. The capacity of their throat pouch allows them to efficiently hunt and stock up on food when it’s plentiful.
How often do they hunt each day?
Brown pelicans feed most actively in the early morning and late afternoon. During peak feeding times, they can make roughly 40-60 hunting dives per day. Dives last around 30 seconds from start to finish. These active foraging bouts are interspersed with resting periods where they preen, socialize, and digest.
On an average day, brown pelicans spend just 1-2 hours actively hunting and diving. Successful dives only occur around 25% of the time, since fish can easily scatter and evade them. Their strategy involves frequent dives in rapid succession to increase their chances of prey capture.
What techniques do they use to catch different types of prey?
In addition to plunge diving for fish, brown pelicans use modified techniques to catch different types of prey:
- Shrimp: Stir up sediment by paddling their feet, then dip bill in water to catch shrimp flushed out.
- Lobsters: Dive and pin lobsters to seafloor before scooping up.
- Crabs: Scoop prey and seawater, then drain out water while tilting bill up to trap crabs.
Their versatile pouch allows them to catch all sorts of slippery marine animals and shellfish. It serves as a built-in net when hunting reef species in shallower waters.
How do mother pelicans feed their chicks?
Adult brown pelicans catch prey in their pouches and bring it back for their young. At the nest, the mother pelican presses her bill against the chick’s and regurgitates food from her pouch right into its mouth. This allows easy, efficient delivery of fish to chicks.
Both male and female parents take turns foraging and feeding the chicks. They are able to provide a steady stream of digestible fish pieces and nutrient-rich regurgitated “chum” to fuel rapid chick growth. Parent pelicans can feed up to 4 chicks in a clutch this way through constant dives and deliveries.
How much fish do they require each day?
Pelican | Fish Required Per Day |
---|---|
Chick | 1-2 lbs |
Juvenile | 2-3 lbs |
Adult | 3-5 lbs |
Brown pelicans are fish-eating machines, requiring up to 4-5 lbs of fish daily – more than 20% of their body weight. Adults consume around 1 lb of fish for every 2.2 lbs of their own weight per day. Their high metabolism and active lifestyle demands a great deal of sustenance.
What adaptations help them swallow large prey?
Brown pelicans have an extremely flexible throat pouch, but they also have adaptations to help swallow large fish once caught:
- Hinged lower mandible – Allows the lower bill to swing widely, creating a bigger gape to swallow large prey whole.
- Stretchy skin and muscles – Skin of the throat and neck can enormously distend.
- Reduced tongue – Their tiny tongue stays out of the way of large passing fish.
- Lack of teeth – No teeth allows slippery fish to slide down easily.
These specializations enable brown pelicans to gulp down fish over a foot long. They flex their neck muscles in waves to sequentially squeeze swallowed fish through the esophagus into the stomach.
What impact does pollution have on their hunting?
Brown pelicans are negatively affected by marine pollution in a few key ways:
- Oil spills – Oil coats their plumage causing hypothermia, drowning, and ingestion during preening.
- Discarded plastics – Plastics are accidentally scooped up and can choke birds or fill their stomachs.
- Harmful algal blooms – Toxins from algae are concentrated in fish and affect birds.
- Chemical pollution – Pesticides, heavy metals, and other contaminants are absorbed by prey fish, then passed up the food chain.
Pollution reduces fish populations and increases the pelican’s exposure to harmful chemicals through their prey. This may affect their dive timing, health, and ultimately survival. Conservation of marine ecosystems is crucial for this vulnerable species.
How do pelican jaws and pouches stay intact?
Brown pelicans have extremely lightweight, rigid skulls comprised mostly of thin bony struts with large air pockets and very little muscle. Despite slamming into the ocean at speeds up to 60 mph, their skulls are resilient enough to withstand the repetitive impact.
Their flexible pouches also stay intact due to:
- Pliable pouch walls 2 layers thick made of stretchy skin and smooth muscle.
- Reinforced rim thickened with more muscle to keep the pouch closed during dives.
- Robust mandible joints allow the lower bill to briefly detach without dislocating.
- Protective plates on the palate allow some water impact cushioning.
Streamlined positioning of their body, neck, and bill when diving further reduces impact on their light but sturdy skulls. Their anatomy disperses collision shocks remarkably well during thousands of high velocity plunges.
How do brown pelican pouches compare to other pelicans’?
The pouch capacities of the 7 pelican species are:
Species | Pouch Capacity |
---|---|
Brown Pelican | 3 gallons |
Peruvian Pelican | 1 gallon |
American White Pelican | 1.5-2 gallons |
Great White Pelican | 1 gallon |
Pink-backed Pelican | 1 gallon |
Spot-billed Pelican | 1.5 gallons |
Australian Pelican | 1.5-2 gallons |
The brown pelican has the largest throat pouch of any pelican species. Their bigger pouches allow them to plunge dive from greater heights and catch more prey per dive. It is an adaptation well-suited to their aggressive diving strategy.
How does their diet vary throughout the year?
Brown pelicans are opportunistic foragers and their diet shifts depending on prey availability:
- Spring – Menhaden, shad, herring, and anchovies that migrate along coasts.
- Summer – Young baitfish in estuaries and mangroves.
- Fall – Leftover populations of anchovies, mullet, and minnows.
- Winter – Deeper sea fish like mackerel when coastal food is scarce.
Their huge pouches allow them to take advantage of seasonally abundant prey. During times of fish shortages, they will eat crustaceans, squid, and even steal prey from other birds.
How does their diving ability compare to other plunge diving birds?
Brown pelicans have some of the most impressive plunge diving capabilities among seabirds. Compared to others:
- Gannets dive from higher altitudes up to 130 ft, but have smaller prey catches.
- Terns have more maneuverability to catch fleeing fish, but very small bills and pouches.
- Boobies have similarly large pouches, but lack the musculature for strong underwater propulsion.
- Cormorants also dive successfully, but only have throat capacity for one fish at a time.
The brown pelican uniquely combines a large, expandable pouch, strong swimming muscles, keen eyesight, and streamlining to excel at plunge diving for multiple small fish with each dive.
How does their dive impact and injury rate compare to humans diving from heights?
Brown pelicans hit the water at speeds and impact forces that would severely injure or even kill most terrestrial animals. Remarkably, they survive thousands of high-velocity plunges unharmed. Compared to humans:
- Pelicans routinely dive from heights over 60 feet at speeds around 60 mph.
- Olympic platform divers jump from around 30 feet and reach 35 mph at impact.
- Cliff divers may jump from 65-85 feet at up to 55 mph.
- Humans can experience serious injury from falls over 30 feet or at speeds above 25 mph.
Brown pelicans withstand impact forces double those felt by Olympic divers after leaping from over twice the height. Their unique adaptations allow them to dive safely from altitudes considered highly dangerous for people.
Conclusion
Brown pelicans are highly specialized plunge divers, using a combination of keen eyesight, streamlined bodies, expansive throat pouches, and strong aquatic propulsion to catch large amounts of fish. Their unusual hunting strategy allows them to capitalize on seasonally abundant coastal prey. Though resilient, pollution threatens their survival by reducing fish populations and introducing toxins. These masters of plunge diving demonstrate how evolution can produce amazing anatomical adaptations for survival in diverse aquatic environments.