Invasive Species-Good or Bad?
Posted: Fri Dec 04, 2015 4:09 pm
To add to the discussions of the need to protect invasive wildlife species (e.g. wild horses and burros) I pose the following situation: This morning I posted an image of a Eurasian collared dove on the birds gallery. Obviously a strikingly pretty species, I question the effects of its taking over habitats formerly occupied by native species (mourning dove), directly competing with them and, being larger and more aggressive, eliminating them from the local ecosystem.
In 2001 I moved to the Sierra foothills and set up my bird feeders. At that time the oaks surrounding the property were nesting and roosting sites for many species, including several mourning doves. In the fall the numbers of this species grew due to their migration from higher elevations where snow prevented their locating food. As many as 25 frequented the area under the feeders gleaning the seeds knocked out by the passerines.
Beginning in 2012 I saw my first Eurasian collared dove, initially mistaking it for a band-tailed pigeon (which do winter in our area) due to its size. Realizing it was a collared dove, I watched it, trying to capture an image but it was very spooky. In 2013 there was a pair coming in fairly regularly. In 2014 there were 3-4 pairs, most roosting in the trees where the mourning doves had been but there were fewer and fewer of the latter. This winter there is a flock of at least 24 and no mourning doves. They clean off the feeding area in a short time leaving little for the native passerines that winter here.
I surmise the collared doves are competing in the niche formerly occupied by the mourning dove and that know that no two species can occupy the same niche. I also realize that the ecosystem doesn’t care much as to the size, shape and coloration of a species, the only issue is its function. So, I ponder these questions:
Personally, I’m on the side of the mourning dove as I feel the system worked pretty well when it was the sole dove here but I much doubt there’s anything I can do to alleviate the issue. Maybe if I stopped feeding the collared doves would go elsewhere and some of the mourning doves would return, but I doubt it as they would just invade new territory and/or limit their numbers to the available feed. Or, I could just shoot the collared doves but I fear the California Department of Wildlife would gleefully have me arrested.
We’ve sure screwed up the system and continue to do so!
In 2001 I moved to the Sierra foothills and set up my bird feeders. At that time the oaks surrounding the property were nesting and roosting sites for many species, including several mourning doves. In the fall the numbers of this species grew due to their migration from higher elevations where snow prevented their locating food. As many as 25 frequented the area under the feeders gleaning the seeds knocked out by the passerines.
Beginning in 2012 I saw my first Eurasian collared dove, initially mistaking it for a band-tailed pigeon (which do winter in our area) due to its size. Realizing it was a collared dove, I watched it, trying to capture an image but it was very spooky. In 2013 there was a pair coming in fairly regularly. In 2014 there were 3-4 pairs, most roosting in the trees where the mourning doves had been but there were fewer and fewer of the latter. This winter there is a flock of at least 24 and no mourning doves. They clean off the feeding area in a short time leaving little for the native passerines that winter here.
I surmise the collared doves are competing in the niche formerly occupied by the mourning dove and that know that no two species can occupy the same niche. I also realize that the ecosystem doesn’t care much as to the size, shape and coloration of a species, the only issue is its function. So, I ponder these questions:
- Does it matter in the long-term if the collared dove replaces the mourning dove? (Their call is somewhat guttural and not pleasing like the mourning dove.) I’ve never seen a live passenger pigeon and have suffered little because of it.
- Did I contribute to this invasion by my feeders? Do the local farmers?
- What additional effects might this have on other native species?
Personally, I’m on the side of the mourning dove as I feel the system worked pretty well when it was the sole dove here but I much doubt there’s anything I can do to alleviate the issue. Maybe if I stopped feeding the collared doves would go elsewhere and some of the mourning doves would return, but I doubt it as they would just invade new territory and/or limit their numbers to the available feed. Or, I could just shoot the collared doves but I fear the California Department of Wildlife would gleefully have me arrested.
We’ve sure screwed up the system and continue to do so!