Raptors Mobbing Raptors

Mobbing is an antipredator behavior where animals mob a predator by cooperatively attacking or harassing it.  This behavior is especially common in birds during nesting and rearing of young.  Typically, it will be a flock of  passerines like Red-winged Blackbirds mobbing a raptor or perhaps a magpie or any other bird they consider to be a threat to their nest or young.   

In mid-June of this year while Mia and I were on another one of our camping/photo forays to Red Rock Lakes National Wildlife Refuge we witnessed a somewhat unusual display of mobbing – raptors mobbing raptors.  We had just returned to our camping trailer when Mia noticed this sub-adult Bald Eagle resting on a muskrat mound almost a quarter-mile away across Lower Red Rock Lake – too far away for quality photos (we had marginal light too) but we simply can’t resist training our lenses on a situation like this just to see if something interesting might happen.  And this time it did. 

 

 Canon 7D, 1/800, f/6.3, ISO 500 ev +1.33, 500 f/4, 1.4 tc

The eagle seemed to be minding its own business and just hanging out for a while on the mound. 

 

 

Canon 7D, 1/640, f/6.3, ISO 500 ev +1.33, 500 f/4, 1.4 tc

But soon a Short-eared Owl (a male I believe) appeared on the scene and he was not happy with the presence of the eagle.  My presumption is that the owl had a nest in the area and it felt the eagle threatened the nest or young. 

 

 

Canon 7D, 1/1000, f/6.3, ISO 800 ev +1.00, 500 f/4, 1.4 tc

The owl repeatedly dived on the eagle and the larger bird was obviously annoyed.

 

 

Canon 7D, 1/800, f/6.3, ISO 800 ev +1.33, 500 f/4, 1.4 tc

Some of the attacks didn’t come particularly close to the eagle but other times it almost appeared like the owl was trying to take the eagle’s head off.  In this sequence of three shots of the same attack the owl is coming in very low and level in an obvious direct threat to the eagle.

 

 

Canon 7D, 1/1000, f/5.6, ISO 800 ev +1.33, 500 f/4, 1.4 tc

And just when it appeared that the owl was actually going to make contact with the eagle…

 

 

Canon 7D, 1/1250, f/5.6, ISO 800 ev +1.33, 500 f/4, 1.4 tc

the owl pulled up at the very last split second.  Actually I’m sure that the distance I was from the action combined with the optical effect of my 500mm lens (with the 1.4 tc and the crop factor of my camera I was effectively shooting at 1120mm) made it appear that the two birds were closer to each other than they really were.  But still, quite the show of bravado from this relatively small owl considering that the eagle, by weight, is about 13 times larger than the owl (9 1/2 lbs vs. 12 oz). 

 

 

Canon 7D, 1/800, f/5.6, ISO 800 ev +1.33, 500 f/4, 1.4 tc

And soon things got even more interesting when this female Northern Harrier joined in the attacks on the eagle. 

  

 

 Canon 7D, 1/1000, f/5.6, ISO 800 ev +1.00, 500 f/4, 1.4 tc

And she was joined by her apparent mate – this male Northern Harrier.  He was particularly acrobatic in some of his dives on the eagle. 

 

 

Canon 7D, 1/800, f/5.6, ISO 640, ev +1.33, 500 f/4, 1.4 tc

And this time, for just a nanosecond, I feared that the male harrier had come too close and would pay the price but he pulled up just in time. 

 

 

Canon 7D, 1/1000, f/5.6, ISO 800, ev +1.00, 500 f/4, 1.4 tc

The attacks continued for some time with all three birds flying around the eagle and seeming to take turns swooping in.   I was never able to get both harriers and the owl sharp in the frame with the eagle at the same time but here you can see that the male harrier has just completed a dive as the owl is beginning his attack.  Very exciting to watch.  I only wish we had been able to get closer to the action for better shots. 

Ron