These bald eagles survey the scene at Pushaw Lake in the hope of finding their next meal. Credit: Courtesy of Bob Duchesne

Ripped from the Bangor Daily News headlines: “Pushaw Lake is becoming a hot spot for northern pike fishing.” It seems I have a front-row seat for this fast-breaking story.

My house overlooks Pushaw Lake, and right now an impressive number of ice fishermen are trying their luck outside my picture window. Fine by me. I’m passionate about birds, but others are just as passionate about fish.

Go for it. Kill as many pike as you can.

A few decades ago, somebody illegally emptied a bucket of pike into Pushaw Lake. Pike are widespread on the continent, but they are not native to New England. In Maine, they are considered an invasive species. Invasive species can cause great damage to the natural environment.

An invasive species is any plant or animal that is transported into a nonnative environment, intentionally or unintentionally. This is distinct from a species that finds its own way to a new environment.

Due to climate change, at least a dozen bird species have moved into Maine as the state has warmed up. But so have ticks. Whenever there is a disturbance to the balance of nature, nature restores the balance — often in ways we don’t like.

I won’t opine on whether the popularity of the pike fishery is a good thing or bad, but there’s no doubt the original introduction was unlawful and unethical. The irony is, some of the fish the voracious pike are eating are also invasive species.

Pushaw Lake is a caldron of fish that weren’t here originally. I worry that nonnative pike eat loon chicks, but so do native snapping turtles. Loon chick predation by either is probably rare. I worry more about eagle predation on loon chicks.

And speaking of eagles, this new ice-fishing bonanza has drawn the attention of quite a flock. Over the weekend, I watched at least 10 on the ice, gathered in one spot where fish guts and bait had been discarded. Give credit to eagles, they’re opportunists.

This tableau unfolding beyond my porch reminds me how much humans change the environment, whether they mean to or not. We’re living in the Holocene Epoch, the current period of geologic history that began with the end of the last Ice Age about 11,000 years ago.

There have been several mass extinctions since life began on earth — all due to natural cataclysms, except for the latest. We’re now experiencing the first mass extinction of creatures caused by the creatures themselves, namely us.

Right now, LD 57 is winding its way through the Maine Legislature. The bill proposes to add eight more species to the Endangered and Threatened List. Five of them are birds. The list is updated every few years, based on the scientific recommendations of the Maine Department of Inland Fisheries and Wildlife.

The saltmarsh sparrow is the most endangered of the five, directly attributable to human-caused climate change. It nests exclusively in salt marshes, which are being drowned by the rising sea levels of a warmer ocean.

The Bicknell’s thrush is a Maine bird that also breeds in a restricted habitat. It has adapted to nesting on cold mountaintops, where competition from other birds is scarce. Although it faces some habitat loss due to the installation of wind power on peaks, climate change is a much bigger threat. As mountaintops warm, the thrush is losing its competitive advantage. It has nowhere else to go.

The blackpoll warbler is now considered threatened, and for much the same reason. It also favors the thick, tangled spruce at higher elevations.

The department recommends that cliff swallows and bank swallows be listed as threatened. They sure are. I’m seriously concerned about how fast they are disappearing in Maine. In fact, many aerial insectivores are declining. The tricolored bat is likewise recommended for the threatened list.  

It’s difficult to reach definitive conclusions about all the contributing factors, but it’s a safe bet that if bug-eaters are declining, it’s because bugs are declining. Whether it’s too many wetlands drained or too much insecticide use, it’s hard to say. But something bad is going on. Whenever the creatures lower on the food chain disappear, those of us on the higher end eventually suffer the consequences.

All too often, human-caused environmental damage is irreversible. Once an invasive species starts reproducing, it’s hard to control or eradicate. Whether it’s harmful insects transported in firewood, aquatic plants transported on trailered boats, or predatory fish transported in a bucket, we almost always wish we’d been more careful.

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Bob Duchesne, Good Birding

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at He can be reached at