Spring Migration & Starlings: How Much Are You Losing To Birds?

 Every spring, millions of birds move north across the United States. For farmers and vineyard managers, that migration doesn’t just signal warmer weather - it signals risk. Among the most problematic species is the European starling, a highly adaptable flocking bird capable of causing serious economic and biosecurity problems.

This article breaks down the real numbers behind crop loss, dairy risks, and what producers should be watching right now.

Why Spring Migration Raises the Stakes

During spring migration, bird populations concentrate around:

• Feedlots
• Dairy facilities
• Vineyards
• Grain storage
• Urban–agricultural edges

Starlings are especially problematic because they:

• Travel in flocks of thousands
• Rapidly learn food locations
• Contaminate feed and water
• Return to reliable food sources year after year

The result is both direct crop loss and disease pressure.

Vineyard Losses from Birds (Including Starlings)

Bird depredation is one of the most expensive wildlife problems in viticulture.

Documented Crop Loss

• The USDA estimates bird damage can average up to 40% of a vineyard crop in affected areas.
• Research from Michigan State University reports losses can reach 95% in red varieties and 60% in white varieties in severe cases.
• Even moderate pressure can cost growers $100+ per acre annually.

Converting That to Pounds

Typical wine grape yield:

• ~4 to 6 tons per acre (8,000–12,000 lbs)

If birds remove 10–40%:

• 800 to 4,800 lbs lost per acre

Revenue Impact Example

Average wine grape value varies widely, but many regions average roughly $600–$1,200 per ton.

Per acre annual loss estimate:

• Low pressure:
  • 0.4 tons lost × $600 = $240/acre
• Moderate pressure:
  • 1.5 tons lost × $900 = $1,350/acre  
• Severe pressure:
  • 3+ tons lost × $1,200 = $3,600+/acre

For a 50-acre vineyard, that can easily mean:

👉 $12,000 to $180,000+ per year in bird damage

And starlings are often the primary culprit because of their flock size and feeding behavior.

Dairy Cattle Risks from Birds

Crop loss is only part of the story. For dairy producers, bird pressure is increasingly viewed as a herd health issue, not just a nuisance.

H5N1 Avian Influenza in U.S. Dairy Herds

The ongoing highly pathogenic avian influenza (H5N1) situation has changed the conversation.

Recent USDA reporting indicates:

• 970+ dairy herds across the U.S. have been affected by H5N1.
• Wild birds are considered the primary reservoir and introduction pathway.
• The virus has spread across multiple states in commercial dairy operations.
  
  

Spring migration increases the risk window because infected wild birds are moving through agricultural regions.

Other Diseases Birds Bring to Dairy Operations

Even outside of avian influenza, starlings and other pest birds are known carriers of pathogens that affect cattle and milk safety.

Key Pathogens Linked to Bird Pressure

Research has shown birds can spread:

• Salmonella
• E. coli
• Campylobacter
• Johne’s disease organisms

Feed Contamination Impact

Studies of starling infestations at dairies have documented:

• Significant feed loss due to consumption
• Nutrient dilution from fecal contamination
• Increased somatic cell counts in some operations
• Elevated pathogen presence in feed bunks

A single starling can eat roughly 1–2 ounces of feed per day, but large winter and spring flocks can number in the thousands, creating meaningful economic loss and health pressure.

Why Starlings Are Especially Dangerous in Spring

Spring creates a perfect storm:

1. Migratory movement
Birds are actively searching for high-energy food sources.

2. Breeding season nutrition demand
Starlings increase feeding intensity.

3. Predictable farm food sources
Feed bunks and ripening fruit become magnets.

4. Roost establishment
Once starlings adopt a site, pressure typically escalates year-over-year.

What Farmers Should Watch Right Now

As spring approaches, monitor for:

• Early morning flock activity
• Feed bunk crowding
• Vineyard edge feeding
• Roost buildup in nearby structures
• Water contamination points

Early intervention is far cheaper than reacting after birds are established.

Bottom Line

Spring migration isn’t just a wildlife event - it’s an economic and biosecurity threat.

• Vineyards can lose hundreds to thousands of pounds of grapes per acre.
• Revenue losses can reach tens of thousands annually for mid-size operations.
• Dairy herds face real disease risk, including H5N1 spillover.
• Starlings remain one of the most efficient agricultural pests in North America.

Producers who monitor early and implement control strategies before flocks build typically see the greatest protection.