Bluebirds vs. Robber Flies: Backyard Birds Break the Rules?

In my previous post, “A Sneak Peek at the New Generation: Eastern Bluebird Chicks,” I shared some adorable photos of the little ones in my backyard birdhouse. But there’s a fascinating story behind the scene of that picture!

Just before I snapped the photo, the male bluebird arrived at the house with a rather unexpected offering for his hungry offspring: a Robber Fly. This wasn’t the first time I’d witnessed this surprising prey choice. It left me wondering – what on earth are these bluebirds feeding their chicks?

Eastern Bluebird With Robber Fly
Eastern Bluebird With Robber Fly

Intrigued, I dove into some online research to see if bluebirds, or birds in general, were known for catching Robber Flies.

Here’s what I found:

Yes, birds can catch Robber Flies. Robber Flies, known for their aggressive predatory behavior and impressive flying skills, can still fall prey to birds. Here’s a closer look at how this interaction unfolds in nature.

Eastern Bluebird: The Agile Insectivore

Eastern Bluebirds are small thrushes that primarily feed on insects, especially during the breeding season when they need to provide high-protein food for their chicks. Here are some key characteristics that make them capable hunters:

  • Keen Eyesight: Bluebirds have excellent vision, which allows them to spot insects from a distance.
  • Agile Flight: They are skilled flyers, capable of quick, darting movements to catch prey.
  • Perch Hunting: Eastern Bluebirds often hunt from a perch, waiting patiently before swooping down on their target.

Robber Flies: Formidable Prey

Robber Flies (family Asilidae) are known for their aggressive hunting tactics and can be challenging prey due to their speed and agility. They have a formidable appearance with long legs, a sturdy body, and a bristly face. Despite this, they can still fall victim to skilled bird hunters.

The Hunt: Bluebird vs. Robber Fly

Here’s how an encounter between an Eastern Bluebird and a Robber Fly might unfold:

  1. Spotting the Fly: The bluebird, perched on a fence post or tree branch, uses its keen eyesight to spot the Robber Fly either resting or flying nearby.
  2. Strategic Approach: The bluebird might observe the fly for a moment to assess its movements.
  3. Quick Maneuver: With a sudden burst of speed, the bluebird launches itself from the perch.
  4. Aerial Pursuit: If the Robber Fly takes flight, the bluebird uses its agility to chase and catch the fly mid-air.
  5. Capture and Consumption: The bluebird grabs the Robber Fly with its beak, then returns to a perch to eat it.

Why Eastern Bluebirds Eat Robber Flies

  • Nutritional Value: Robber Flies, like other insects, provide a good source of protein, essential for the bluebird’s diet, especially during the breeding season.
  • Abundant Prey: Robber Flies are often abundant in the bluebird’s habitat, making them accessible prey.
Eastern Bluebird With A Different Robber Fly
Eastern Bluebird With A Different Robber Fly

Conclusion

Eastern Bluebirds are more than capable of catching and eating Robber Flies, thanks to their sharp eyesight, agile flight, and strategic hunting tactics. This interaction is a testament to the bluebird’s role as a proficient insectivore in its ecosystem. Next time you’re out in the field, keep an eye out for these beautiful birds—you might just witness them in action, turning a fearsome Robber Fly into their next meal.

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