Hummingbirds on the attack

As we cruise through September, many of our summer visiting birds are starting to migrate south, including the beloved ruby-throated hummingbird. I’ve written about this popular species a few times this summer but it seems fitting to squeeze in a final question before they leave us until next spring. Bernie in Dayton sent in a fun question to ponder, which was, put simply: “Why does a male ruby-throated hummingbird chase the female away whenever she tries to use one of our three hummingbird feeders?”

The quick answer is that male hummingbirds are horrible husbands, but we can dig deeper than that.

Some studies that have looked into the territoriality of ruby-throated hummingbirds essentially found that the primary function of a male’s territory is to be an adequate food source, and that having it as a mating territory is only secondary. I like to say that the purpose of life (from a bird’s perspective) is to make copies of themselves, so obviously a male needs to be able to attract a female, and food is apparently the way he does that. If the food-based territory isn’t adequate enough to attract a female, the male will move to a new area. The males have amazing aerial displays they’ll perform to woo a female, but that is about where their involvement in parenting stops. When a female enters the male’s territory, his behavior is described in literature as “harass(es) but (does) not evict.” After this courtship, almost all of the male’s focus is on evicting any competition for food.

There is a wonderful quote in a 1942 paper by Frank Pitelka on his study and observations of a hummingbird in the summer of 1939, which goes: “The general belligerence and intolerance observed in the behavior of the Ruby-throated Hummingbird prevails apparently in all (hummingbird) species on which information is available.” You’ll see this behavior if, like Bernie, you have a hummingbird feeder in your yard. Territorial males will chase off not only the females but other birds and even bees. During our Thursday morning bird walk at Gilsland Farm in Falmouth earlier this month, we saw a ruby-throated hummingbird relentlessly chasing a downy woodpecker around an apple tree!

Before leaving the subject of hummingbirds, I always feel compelled to make the plea for folks to keep their hummingbird feeders up in the fall. Although the majority of our ruby-throated hummingbirds will have departed by early October, the feeders can act as an important fueling station for late migrants or as an attractant for vagrants from the west. We are increasingly seeing western species like rufous hummingbirds coming east in the fall, with most sightings coming from feeders that are left up through October and even November. I recommend keeping them up until just before you think the sugar water would freeze. And then shoot me an email if you see any hummingbirds after the first week of October!

Have a heart and reconsider the Havahart

A frequent question we get at Maine Audubon – but an especially important one to consider at this time of the year – is about the ethical use of trapping and relocating unwanted wildlife from one’s yard. It may seem harmless; take that smelly skunk and move it across the river so that it stays out of your yard. The reality of what happens after moving that animal is less rosy.

First of all, I should clarify an important distinction between relocation and translocation. The relocation of an animal usually involves moving it from an unwanted place to another, but keeping it within its home range. For example, imagine a skunk or raccoon accidentally finding its way into a basement through a bulkhead door left open. Setting a trap to capture that individual so it can be released back outside is relocation. In contrast, trapping a skunk that has been eating grubs in your yard, and driving it to the next town over and releasing it in the wild is translocation. With that in mind, many of the cases we hear about are people attempting to translocate wildlife.

The problem with translocation is that it often results in very high mortality rates. By taking an animal out of its home range, it may not be able to find food or shelter, or will have to compete with the animals (and predators) that are already established in that new area. A study in Ontario that tracked translocated raccoons with radio collars found that mortality was around 50% within the first three months of being released, and as high as 75% following that. Another study in North Carolina looking at survivorship of translocated raccoons found only about 16% survived. Numbers vary for different species and locations, but they tend to be quite high. Gray squirrels are one of the most commonly translocated species and a study by the Humane Society of the United States found that 97% of squirrels died or disappeared (mostly from predation) within 88 days of being released.

It is also important to keep in mind that your yard has some carrying capacity for the wildlife that is currently there. Simply put, your yard can sustain a certain amount of wildlife because of the food and habitat that is there. So just removing the “problem animal” won’t solve the problem of having animals around, because eventually that removed animal will be replaced. So, if woodchucks are a problem for your garden, you’ll have much more success in the long term by installing proper fencing (and burying part of it) and letting that critter keep your dandelions mowed, rather than translocating it, an almost certain sentence of doom.

Have you got a nature question of your own? Email questions to ask@maineaudubon.org and visit maineaudubon.org to learn more about backyard birding, native plants, and programs and events focusing on Maine wildlife and habitat. Doug leads free bird walks on Thursday mornings, 7 to 9 am, at the Gilsland Farm Audubon Sanctuary in Falmouth.

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