Plant a Sitka Spruce, Get a Finch… or when is a new species an invasive species?

Common Redpoll, Sitka Spruce Grove
Chignik Lake, February 3, 2017

Up and down Southwest Alaska’s Alaska Peninsula, Redpolls, Siskins, Crossbills and Grosbeaks – all members of the finch tribe – have typically been marked as uncommon, rare or absent, breeding in small numbers here and there but generally not species one expects to encounter on the windswept peninsula. However, as trees – particularly alders -, have become increasingly abundant in that part of the world, so too have the finches. Seeds of the tiny alder cones are relished by Redpolls; the tender leaf buds by Pine Grosbeaks. But nowhere has the recent emergence of trees more dramatically impacted avian life than in the village of Chignik Lake where 70-some years ago Sitka Spruce trees were transplanted from seedlings gathered on Kodiak Island.

Some of the spruce trees at The Lake now tower over the landscape, producing both shelter and food for a wide variety of birds. The seeds of mature cones draw Pine Siskins, Hoary and Common Redpolls, White-winged and Red Crossbills, Black-capped Chickadees, Black-billed Magpies and several species of sparrow. While they’re still soft and reddish-purple, immature cones are feasted on by Pine Grosbeaks. Meanwhile, the variety of invertebrates that have moved into the little groves of spruce trees provide sustenance for Downy Woodpeckers, Pacific Wrens, Golden-crowned Kinglets and Yellow Warblers. Great Horned Owls roost and nest in the dark shadows of spruce bows and Northern Shrikes, Merlins and an occasional Sharp-shinned Hawk hunt the songbirds attracted to the trees. My guess is that it’s only a matter of time – and not too distant time – before the first Steller’s Jays are reported at The Lake. In fact, based on a description a now deceased resident reported to me, I’m not sure they haven’t already been there.

But here’s a question: Are these trees actually an invasive species… like the Orange Hawkweed that only very recently has begun showing up at The Lake? Or, for that matter, the dandelions which have taken over the school yard (and also, in some years, provide food for the finches as they go to seed)? And what about the above-mentioned alders that are steadily crowding out what remains of the peninsula’s tundra?

For decades, the transplanted Sitka Spruce trees did not propagate themselves in the Chignik Drainage. But about five years ago that began to change when seedlings suddenly began volunteering themselves throughout the village. One might argue that even without human intervention it was only a matter of time before Picea sitchensis made its way down the peninsula. But couldn’t the same be said of the Orange Hawkweed, dandelions and even the Kamchatka Rhododendron that has naturally, over time, found its way to The Lake from its native grounds in far eastern Russia?

Dumping a bucket of carp or pike into a lake where they never before existed is one thing…

On the other extreme are dandelions and hawkweed, which seem to to have devised strategies to show up wherever environmental conditions suit them.

Somewhere in between are a vast array of flora and fauna that – with or without humankind’s assistance – are finding their way into new niches.

So, what do you think? Where is the line between happily-received newcomer and dreaded invader?

7 thoughts on “Plant a Sitka Spruce, Get a Finch… or when is a new species an invasive species?

  1. Great question! My gut tells me a plant, a verterbrate or inverterbrate is an invader when it causes extinctions of other species.Otherwise its a question of balance and if it can coexist with everything around it then I would call it natural in the loosest sense of the word.

  2. I had a similar thoughts as the fellow blogger above: if an introduced species coexists with the native plants and animals without causing harm, it’s welcome. Whether or not that’s even biologically possible, I don’t know

    • Thanks for weighing in. You got right to the core of it: “…coexist…without causing harm…(if) that’s even biologically possible.” I think of the Great Horned Owls in those trees. Fierce predators, it’s a veritable boneyard beneath their roosts, the remains of hares, voles, ermine, magpies… even a kingfisher bill. So, are these owls, which would probably not be there but for the spruce trees, competing with predators that are native to the ecosystem (lynx, ermine, various hawks and falcons)? And are these large owls limiting smaller owls (such as Saw-whet Owls) that might naturally move into the area? On the other hand, there is no disputing that these trees have been a boon to several species of passerine… and have almost certainly Increased local bio-diversity and vertebrate density.

  3. Invasive species that cause problems are the ones that not only move in, but eliminate others; e.g., snakes that almost eliminated birds in Hawaii, the Burmese python in the Everglades doing huge damage, the Australian pine along Florida’s coasts whose needles eliminate all undergrowth, native plants and habitat for birds and mammals. With that thought in mind, I suppose the question is whether previously native species can survive the presence of the new one.

    • Good Morning from very cold Cordova, Alie & Ray. You’re interpretation jibes with that of the U.S. Department of Agriculture – harmful + not naturally occurring = invasive; not harmful + not naturally occurring = simply non-native. It’s an interesting topic that I’ve had in the back of my mind for many years but never really explored. I hadn’t heard about the Australian Pine in Florida… Thanks for your thoughts and the information!

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