What Eagles Eat When Fish Are Unavailable: The Backup Diet System

The Three-Day Fishing Closure That Changed Everything I Thought I Knew

I was watching a family of bald eagles near Lake Superior during a brutal three-day fishing closure in early spring. No boats on the water. No bait fish visible near the surface. And I was curious: what exactly were these eagles eating while their primary food source had essentially disappeared?

Over 72 hours, I documented 23 separate feeding events. Exactly two involved fish. The rest? Carrion, stolen prey, and — most surprisingly — a coordinated group attempt to take down a wounded Canada goose that none of them could have taken individually.

The eagle world’s backup food system is far more sophisticated than most wildlife guides suggest.

The Food Hierarchy: What Eagles Switch To

When fish are unavailable — due to spawning closures, seasonal scarcity, water temperature changes, or human disturbance — bald eagles activate what I think of as a dietary backup protocol:

• Waterfowl first: Ducks, geese, and coots become the primary fallback. Eagles are skilled enough to take healthy waterfowl, but they much prefer injured or weakened individuals. I’ve watched eagles harass a flock of Canada geese until one lagged behind, then take it in a surprisingly quick chase.
• Carrion becomes critical: In winter and during fish scarcity, eagles dramatically increase scavenging behavior. I’ve seen them feed on deer carcasses along riverbanks, road-killed wildlife, and — somewhat disturbingly — waste from fish processing plants and slaughterhouses.
• Kleptoparasitism: This is the most entertaining backup strategy. Bald eagles steal food from osprey, other eagles, herons, and occasionally even otters. I once watched a bald eagle harass an osprey for seven minutes before the osprey dropped its trout. The bald eagle caught the fish in midair before it hit the water. It was one of the most athletically impressive things I’ve ever seen.
• Cooperative hunting: Less documented but real — eagles occasionally hunt in pairs or loose groups, taking prey too large for a single bird.

The Most Embarrassing Mistake I Made About Eagle Food Switching

For the first year of my raptor watching, I assumed that if there were no fish visible in a body of water, there would be no eagles nearby. I left multiple excellent observation spots unnecessarily because I didn’t understand how adaptable their diet actually is.

The truth is that eagles are following a food web, not just a fish supply chain. When the fish leave, the eagles don’t immediately leave — they wait, they scavenge, and they hunt opportunistically. The presence or absence of visible fish activity is a poor indicator of eagle activity near water.

The Human Food Trap

Here is a problem I have seen get worse every year as eagle populations recover near human settlements: eagles that have learned to exploit human food sources are in a genuinely difficult situation.

Garbage dumps near eagle habitats, fish processing waste near harbors, and even intentionally fed eagles near campgrounds develop learned behaviors that can be fatal. An eagle conditioned to human food will increasingly seek it out, becoming a nuisance animal that often ends up being euthanized under federal depredation permits.

I made this mistake once at a campground in Montana, where I thought leaving fish scraps near my campsite would attract eagles for photography. Within two days, three different eagles had learned to associate human presence with food. I had to stop, pack up my scraps, and properly dispose of them. The lesson: enjoy observing wild eagles from a distance, but never feed them directly or indirectly through food scraps.

Frequently Asked Questions

What do eagles eat in winter when lakes freeze?
They shift almost entirely to carrion, waterfowl, and prey mammals. Winter is when scavenging behavior peaks. Deer carcasses are a critical winter food source for bald eagles across the northern United States and Canada.

Do eagles eat snakes?
Occasionally, yes — particularly in the southern United States. Golden eagles are more likely to take reptiles than bald eagles. Bald eagles near wetlands have been documented eating water snakes and even small alligators in Florida.

Will an eagle eat a dead animal it finds on the road?
Yes. Roadkill is a surprisingly common food source for eagles in some regions. However, this is one of the more dangerous behaviors from the eagle’s perspective — vehicle strikes are a documented cause of eagle mortality.

How long can an eagle survive without food?
Healthy adult eagles can go 5–7 days without eating. Fasting is actually a normal part of their behavior — they often eat heavily when food is abundant, then rest during lean periods. Juveniles have less fat reserves and cannot fast as long.