Ducks are a common sight in ponds, lakes, and rivers. But where do they fall in the food chain? Are they primary producers like plants, primary consumers that eat plants, or secondary consumers that eat other animals? Read on as we quack open the details.
If you’re short on time, here’s a quick answer: Ducks are generally considered secondary consumers because they typically eat insects, small fish, aquatic plants and sometimes small amphibians and mollusks.
However, ducks are omnivores and can also graze on plant material, which would make them primary consumers.
Defining Food Chains and Trophic Levels
Producers and Consumers
A food chain describes how energy and nutrients flow through an ecosystem. It shows the feeding relationships between organisms within a habitat. The starting point of any food chain are producers. Producers, mainly plants and some bacteria, are able to make their own food through photosynthesis or chemosynthesis.
Through these processes, producers convert energy from sunlight or chemicals into stored energy in the form of carbohydrates. Plants and algae are examples of producers found in aquatic and terrestrial food chains.
Organisms that eat producers or other consumers are called consumers. Consumers are unable to make their own energy, so they rely on the food they eat to obtain energy. Consumers come in three main types: primary, secondary, and tertiary consumers.
The differences between them depend on their place in the food chain.
Primary, Secondary and Tertiary Consumers
Primary consumers are always herbivores, meaning they only eat producers like plants and algae. Some examples are zooplankton, insects, rabbits, deer, and some birds. Primary consumers are a vital link between producers and other consumers higher up the food chain.
Through eating plants, they transfer the energy stored by producers into a form that can be used by other organisms.
Secondary consumers only eat primary consumers or other secondary consumers. They are carnivores or omnivores. Secondary consumers include small fish, snakes, raccoons, and spiders. By eating primary consumers, secondary consumers receive the energy that originated from producers further down the food chain.
At the top of the food chain are the tertiary consumers. Also called apex predators, they have no natural enemies other than humans. Tertiary consumers eat secondary consumers for energy and nutrients. Examples include large fish, seals, wolves, hawks, lions, and sharks.
As tertiary consumers, they receive energy that has passed through at least two previous levels in the food chain.
Understanding how organisms are linked in food chains and their trophic levels helps illuminate the interconnected relationships between producers, primary consumers, secondary consumers, and tertiary consumers in an ecosystem.
Knowing how energy flows through food chains provides crucial insight into how ecosystems function.
The Duck Diet: An Overview
Insects and Other Invertebrates
Ducks consume a wide variety of insects and invertebrates like dragonflies, flies, midges, caddisflies, amphipods, beetles, and aquatic worms. These small creatures make up a decent portion of a duck’s nutrition. Studies show that invertebrates can comprise 10-40% of a duck’s annual food intake.
This large range depends on the duck species, time of year, and habitat. For example, dabbling ducks eat more invertebrates in the spring and summer when aquatic insect hatches occur. Certain diving ducks like lesser scaups feed heavily on amphipods which are small shrimp-like crustaceans.
Fish and Amphibians
Fish are an excellent source of protein for ducks when available. Ducks will readily eat small fish, eggs, tadpoles or even baby turtles if they can capture them. The percentage of fish and amphibians in a duck’s diet varies by habitat and season, but studies show they consume these prey 5-30% of the time on an annual basis.
Some examples of fish ducks eat include minnows, sunfish, perch, sticklebacks and more that live in freshwater ponds, lakes, rivers and streams. Ducks that winter at coastal habitats get to feast on marine fish and invertebrates like killifish, silversides and shrimp.
Seeds and Aquatic Plants
The third major component of a duck’s diet consists of vegetable matter, primarily from aquatic plants. Ducks will eat things like pondweeds, spike rushes, water lilies, arrowheads, wild rice, millet, and smartweeds.
The seeds, stems, leaves and roots from these plants provide essential carbohydrates.
The percentage of plant matter ducks eat depends greatly on geography and season. For example, northern pintails wintering in flooded agricultural fields of California’s central valley consume 90-100% plant material.
On breeding grounds the number is closer to 30-50% as protein from insects becomes more important for egg production and duckling growth.
To summarize, the diverse duck diet consists mainly of insects, fish/amphibians and aquatic plants. The proportions vary by habitat, season and life stage. But this flexible nutritional strategy serves ducks well across an impressive range of wetland ecosystems!
Why Ducks Are Generally Considered Secondary Consumers
Ducks are omnivorous birds that feed on a variety of plant and animal matter, which places them in the secondary consumer level of most food chains and webs. Here’s a closer look at why ducks are classified as secondary consumers:
They Eat Primary Consumers
One of the defining features of a secondary consumer is that they eat primary consumers – creatures that only eat producers like plants. Ducks commonly eat insects, worms, small fish, tadpoles, and other animals that are primary consumers.
By preying on these creatures, ducks occupy the secondary consumer niche.
They Are Prey for Higher Level Consumers
In addition to eating primary consumers, secondary consumers are often food sources themselves for tertiary or higher-level consumers. Ducks are preyed upon by foxes, coyotes, snakes, hawks, eagles, and other carnivorous animals.
Their role as both predator and prey is a key sign that they are secondary consumers.
They Have a Diverse Diet
Omnivores like ducks that eat both plant and animal matter are almost always secondary consumers. Their flexibility to eat producers like plants, algae, and fungi when necessary, along with primary consumers for protein sets them firmly in the secondary consumer category.
They Are Not Top Predators
Secondary consumers have predators of their own. As previously mentioned, ducks must watch the skies and waters carefully to avoid becoming food for hungry tertiary consumers. True apex predators or top carnivores that have no natural predators are rare.
Ducks do not qualify as apex predators, keeping them squarely as secondary consumers.
They Provide Energy Transfer
A key role of secondary consumers in an ecosystem is energy transfer. Ducks transfer the energy gathered by primary consumers like insects to the higher-level predators that eat them. This allows energy to move up the food chain, while also helping regulate primary consumer populations.
Exceptions and Special Cases
Dabbling Ducks
Dabbling ducks, such as mallards, teals, wigeons, and pintails, typically feed on plants, seeds, and aquatic invertebrates, making them primary or secondary consumers. However, there are some exceptions.
During the breeding season, male dabbling ducks do not feed much and instead focus their energy on attracting females. Their diet shifts to whatever food sources are most readily available during this energetically costly period of courtship displays and mating activity.
The food sources vary depending on the location, but can even include small fish, frogs, salamanders or insects if easily accessible, temporarily shifting them to a higher trophic level.
Sea Ducks
Sea ducks, such as eiders, scoters, goldeneyes, and long-tailed ducks, are usually secondary consumers feeding on shellfish, aquatic plants and insects, small fish and crustaceans. However, some species like Steller’s eiders have a more varied diet depending on seasonal availability.
Their hypothesized trophic level ranges from 2.0 during winter to 2.8 during breeding season when they consume more animal matter. Surf scoters similarly show variation, shifting from a largely herbivorous diet to one consisting of up to 90% mollusks depending on habitat and season.
These fluctuations to take advantage of accessible food sources complicate defining a fixed trophic level for sea duck species with versatile diets.
Conclusion
To summarize, most ducks are considered secondary consumers because the bulk of their diet consists of small fish, aquatic invertebrates and insects. However, as omnivores ducks show flexibility in their feeding habits.
Their ability to shift between different food sources helps them thrive in a variety of wetland ecosystems.
