I wasn’t sure whether this subject would be suitable to a Bucket. It depicts an act of predation. However some bucketeers have suggested I tell the story, so with the heads up below, I will, below the page break.
WARNING: Predator/prey interaction below. Feel free to skip the diary content and go directly to the comments.
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January 21, 2023
Salish Sea, Pacific Northwest
A few days ago I was heading home on my daily walk when I heard a lot of sudden bird activity behind me: gulls, crows and a heron calling in alarm. When I looked, I saw an eagle flying low over the bay, amidst a swirl of gulls and crows, chasing a Great Blue heron. I was about a quarter of a mile away so my pics are not great, but this series of photos shows what I saw from my vantage.
The heron landed in the water a ways from shore. Herons are poor swimmers at best, from what I’ve read. They have wading feet. There are reports and videos on the internet of them swimming but it’s generally in water shallower than the length of their legs, so they might be walking along the bottom. Still, most animals can propel themselves in the water to some extent, and this heron appeared to be just floating. That suggests it was injured or stunned by the attack and couldn’t stay airborne any longer, where it would surely have been better able to evade the eagle.
Eagles kill their prey quickly, which reduces the chance of being injured themselves, or losing it. An eagle’s hunting success rate is only about 20% and they require up to a pound of food a day, so they must be on the lookout for good hunting opportunities. Catching a heron is a high reward hunt but there’s also a considerable energy cost, not just the catching but getting it out of the very cold water here.
At this point the heron was dead and it looked like both birds were adrift in the water, several hundred feet from shore. Now what? Then I realized the eagle was dragging the heron toward the nearest dry land. Swimming! by using its wings to propel it across the surface.
I figured it would take a few minutes for the swim so I walked back to the beach to see if I could get a better look at what was happening. By the time I got back down there, I saw the eagle had dragged the heron onto a big rock near the beach. Shortest possible distance for it to swim.
From the beach I could see the eagle had dragged the heron up onto the rock. Quite a few gulls and crows were flying around, or in the water or on the rock nearby. A couple of crows managed to sneak in for scraps but for the most part they all kept a respectful distance. The eagle frequently looked around as though watching for big birds.
I took some video. Here’s a 40 sec set of clips showing the eagle swimming, plucking and maneuvering the heron on the rock.
According to Birds of the World, while eggs and nestlings are commonly preyed on by raptors and mammals, it’s rare for a full grown heron to become prey. And when they do, the predator is almost always an eagle. If this was indeed a heron who hatched out last summer, this youngster was among the many birds who sadly do not survive their first year (percents vary between species, in general about 50%, though a study of Great Blue Herons in Britain from 1916-1945 found that 71% died in their first year). Inexperience and bad luck ended this heron’s life in its first winter.
I've been thinking a lot about this incident, after considering my own and other people's reactions. Mostly, friends and neighbors have responded feeling sorry for the heron, and to be honest I feel that way too, even though I’ve seen a variety of animals being eaten by eagles. One friend said “You'd think with the 50 million rabbits on the island they’d be satisfied with hunting those”.
Pretty much everyone (that I know) finds eagles magnificent beautiful creatures. But eagles are also obligate carnivores, like many animals (eg. lions, seals, whales, owls, seastars, and in fact also herons), meaning they have to eat meat to survive. We all accept that. And yet it’s common for us to feel differently about some predator/prey interactions. Why? Some possibilities, using the eagle/heron situation as an example:
- we care more about herons as prey than fish (because they’re prettier, or more like us?)
- herons don’t cause us any trouble, unlike rabbits or rats
- herons aren’t under our protection or economically valuable, like chickens
- herons aren’t abundant, as compared to, say, fish
- eagles are fairly common (around here), unlike other predators such as owls or cougars (which don’t prey on herons, but you get the idea)
- age of prey: are we more sympathetic when a young animal is preyed on? Would we feel the same about an old or disabled prey animal? (or the reverse?)
What are your thoughts? What are some predator/prey interactions in your neighborhood, and do you feel more sympathetic for some prey than others?
Windy and rainy in the Pacific Northwest islands today. Temps in the high 40s.
WHAT’S UP IN NATURE IN YOUR AREA TODAY?