White pelicans are large waterbirds that are found in inland and coastal areas in North America. They are known for their huge bill and throat pouch, which they use to scoop up fish to eat. White pelicans mainly eat small fish that swim in schools near the surface of lakes, rivers and coastal waters. Their diet consists primarily of non-game fish species such as minnows, suckers and perch. By understanding what fish white pelicans feed on, biologists can better understand their ecological role as fish-eating birds.
Main Fish Species Eaten by White Pelicans
White pelicans are opportunistic feeders and eat a variety of fish species depending on availability and location. The main types of fish consumed include:
Fish Species | Description |
---|---|
Carp | Various minnow species in the carp family Cyprinidae, especially common carp. Widespread and abundant. |
Catfish | Various bullhead and catfish species, especially black bullheads. Bottom-dwellers. Abundant. |
Suckers | Various sucker species in the Catostomidae family, including redhorse suckers, white suckers and creek chubs. Tend to congregate in schools. |
Perch | Includes yellow perch and walleye. Swim in large schools in open water. |
Alewives | A small forage fish that forms large schools near the surface. Common prey. |
Shad | Gizzard shad and threadfin shad. Fast-swimming schooling fish. |
Herring | Species like American shad form dense schools and are readily consumed. |
Minnows | Various minnow species across multiple families. Abundant small fish prey. |
These fish provide rich sources of nutrition for white pelicans while also being easy targets given their schooling behavior, small size and abundance. The large pouches of white pelican allow them to scoop up and consume multiple fish at a time.
Preferred Habitats and Feeding Behavior
White pelicans frequent shallow lakes, marshes, estuaries and river channels while foraging for fish. Their ideal fishing areas provide ample concentrated small prey fish near the water’s surface. During feeding, pelicans will work together to corral fish into compact balls or pursue scattered schools. Plunge-diving from the air or surface, they trap fish inside their elastic throat pouches. The pouch can expand to hold up to 3 gallons of water and fish. After draining the water, they swallow their catch.
Regional Differences in Diet
While the overall fish diet is similar across populations, the specific species composition varies by location and season. For example:
- Inland pelicans in lakes may eat more carp, perch, suckers and bullheads.
- Coastal populations consume more Atlantic menhaden, mullet, anchovies, and other ocean schooling fish.
- In the Pacific Northwest, pelicans rely more on smelt, salmon, alewives and other migrating species.
- In the Southeast, shad and sunfish may dominate the diet.
This adaptability allows white pelicans to thrive across a wide geographical range and take advantage of whatever small fish are locally abundant.
Fish Size and Calories Consumed
White pelicans are large birds with high caloric needs. On average, they require around 1.4 lbs or 635 grams of fish per day to meet their energy demands. The estimated annual consumption of fish per pelican is between 440-600 lbs.
The size of fish eaten averages about 4-8 inches long and less than a 1/4 pound in weight. A single pelican’s pouch may hold up to 3 gallons of water and fish totaling up to 5 pounds. However, most individual fish are small minnows and forage fish under 3 inches long. These small fish allow the birds to efficiently capture enough calories and nutrition to sustain their active lifestyle.
Daily Food Intake
The estimated daily fish consumption by white pelicans equals:
- About 1.4 lbs or 635 grams of fish
- 9-12 medium-sized fish 4-6 inches long
- 50 or more smaller fish like minnows
- Calories ranging from 650-950 calories per day
This sizable fish intake allows white pelicans to meet their high energy needs, especially during breeding season when energy demands peak. The abundance of schooling fish in their preferred habitats makes it possible for the birds to capture enough prey.
Role as Fish-Eating Birds in Food Chain
As fish-eating birds, white pelicans play an important ecological role in aquatic food chains and ecosystems.
Impacts on Fish Populations
White pelicans can significantly influence fish populations and community structure through their predation. By selectively feeding on the most abundant small fish species in an area, pelicans help regulate these fish populations. Their feeding prevents any one prey species from dominating the ecosystem.
Typically pelicans do not threaten overall fish populations. However, localized impacts may occur in specific lakes or rivers. White pelicans may compete with commercial fisheries or negatively impact recreational sport fisheries in some instances by reducing densities of preferred game fish.
Energy Transfer in Food Chain
As predators high on the food chain, pelicans provide an important energy transfer linkage. They consume large volumes of small fish that feed on aquatic plankton and insects. In turn, piscivorous fish, birds of prey and other wildlife consume adult pelicans or scavenge their eggs and young.
This energy flow up the food chain helps support reproduction and maintain ecosystem biodiversity. White pelicans are an integral component of healthy aquatic and wetland habitats across North America. Their populations and prey consumption reflect the overall productivity and health of these ecosystems.
Factors That Influence Fish Consumption
A number of factors influence the quantity and type of fish white pelicans consume:
Prey Availability
This is the most important factor driving their variable diet. As opportunistic feeders, white pelicans switch prey based on whatever fish are most abundant and easiest to catch in the area.
Schooling fish like shad, carp, or perch that congregate in large groups near the surface provide ideal calorie-rich meals for pelicans. In contrast, solitary bottom-dwelling fish are more difficult to target and capture efficiently.
Habitat Quality
Higher quality wetland and coastal habitats with ideal foraging grounds lead to greater fish consumption. Shallow, calm waters with good water transparency facilitate spotted prey. And abundant emergent vegetation provides habitat for young fish to shelter.
Loss or degradation of marsh breeding and fishing grounds will reduce available prey for pelicans. Ongoing wetland conservation is therefore crucial.
Seasonal Factors
Prey abundance, fish behaviors, and pelican energy needs change across seasons. In warmer months, small fish reproduce prolifically providing ample food. Before migration in winter, pelicans may target calorie-dense fish to build fat reserves.
Year-round residents show seasonal shifts in diet tracking fish availability. Migration also exposes pelicans to different regional prey fish species.
Fishing Competition
Fishing pressure from human recreational and commercial fisheries can potentially limit prey fish stocks. But pelicans are opportunistic and simply switch target species, so competition is usually minimal.
However, overfishing may decrease forage fish populations that pelicans rely on in certain lakes or coastal areas. Management is needed to balance fishery harvests and ecosystem needs.
Pollution and Disease
Pollution can degrade water quality and reduce fish habitat and health in freshwater ecosystems. Algal blooms from fertilizers can be toxic to fish. Chemical pollution may also accumulate in fish consumed by pelicans.
Disease outbreaks like avian botulism can periodically impact fish-eating bird populations dependent on certain lakes or wetlands. Habitat protection helps minimize these events.
Comparison to Other Fish-Eating Birds
White pelicans inhabit similar aquatic environments and share prey with other large piscivorous birds including:
Brown Pelican
- Coastal species that plunge dives for ocean fish like anchovies, menhaden, herring, and mackerel near shore.
- Require up to 1.6 lbs of fish daily, targeting smaller prey than white pelicans.
- Only pelican species that is primarily marine.
Great Blue Heron
- Wading bird that stalks and spears a variety of minnows, perch, catfish in shallows of rivers, lakes and wetlands.
- Requires about 0.5 lbs of fish per day on average.
- More solitary hunter compared to highly social white pelicans.
Cormorants
- Fish-eating waterbirds that dive and swim underwater to catch prey.
- Eat similar fish species as white pelicans.
- Smaller diet and fish consumption than white pelicans.
- Found along coasts, rivers and lakes year-round.
Osprey
- Specialize in catching fish at water’s surface by plunge diving.
- Require 1-2 lbs of fish daily.
- Take larger prey on average than white pelicans.
- Migrate long distances tracking fish populations.
While filling a similar niche, white pelicans tend to forage more efficiently in groups and require higher fish intake overall compared to these other piscivorous birds. Their adaptable schooling fish diet allows them to thrive across diverse aquatic habitats.
Impacts of Pelican Predation on Fish Populations
The fish consumption of white pelicans does exert some natural predation pressure and influence on local fish populations and community structure. However, pelicans rarely devastate or decimate overall fish stocks of any species.
Positive Impacts
- Pelican predation helps regulate abundant small prey fish that could outcompete other species if left unchecked.
- Pelicans help control populations of invasive fish species in some cases.
- Feeding weeds out weaker, less fit individuals from prey fish stocks.
- Scavenging on dead or dying fish helps recycle nutrients and clean waterbodies.
Negative Impacts
- May compete with human recreational or commercial fisheries for certain shared target fish species.
- High densities of nesting pelicans can temporarily deplete prey fish around colonies.
- Some localized impacts to fisheries or sportfish have been documented but are usually minimal.
Mitigation Strategies
- Sustainable fishery management practices that don’t overharvest fish stocks.
- Wetland conservation and pollution control to nurture healthy aquatic ecosystems.
- Relocation or dispersal of problematic high-density pelican colonies when needed.
- Public education about the natural role of pelicans in ecosystems.
Overall, white pelicans serve as an indicator species reflecting ecosystem conditions. Ongoing research and monitoring continues to deepen understanding of pelican-fish dynamics for informed conservation.
Conclusion
White pelicans consume a diversity of small schooling fish such as carp, catfish, perch and minnows. While adaptable in their diet, they depend on abundant populations of forage fish concentrated in prime shallow fishing grounds. As large fish-eating birds, pelicans exert natural predation pressures on prey species, while also serving as an important energy transfer link in aquatic food webs. Although localized impacts may occur, their fish consumption rarely threatens overall fish stocks or ecosystems. Conservation of vital wetland habitats will help ensure healthy fish populations that can sustain white pelicans and other wildlife into the future.