The Squirrel Census Answers a Question You Weren’t Asking

So in a sense introducing them to parks in those cities was just putting back what we had driven off.

It's interesting that the Eastern Gray squirrel was also introduced to parks in Seattle. The Eastern Gray is not native out here. The native squirrels out here are the Western Gray, the Douglas, the Red, and the Northern Flying squirrels.

That raises the question of why when they decided they wanted squirrels in the parks that they went to the trouble of importing Eastern Grays from the other side of the country, instead of just sending someone out to trap a few Western Grays and release them in the parks.

It turns out that the reason is that a lot of the parks feature non-native trees. Western Grays really want to live off of native trees, and so don't do well in those parks. Eastern Grays either are native to the same places the non-native trees are native to, or are happy with them anyway, so they do fine in Washington parks, regardless of whether or not those parks feature native plants or non-native plants.

That also means the Eastern Grays did fine when they left the parks, and they have pretty much completely replaced the Western Gray. There's now only three isolated populations in the state, where once they were widespread and common.

In short, they started to be introduced into parks in the 1850's or so, and were a bit of a national craze.

If they couldn't get enough volunteers, the natural next step would seem to be counting a sample of the 350 plots rather than all of them.

He said the methodology of dividing up into hectares had to do with squirrel behavior. They tend to mostly live within about a 100x100m area, so it was an easy way to be relatively accurate.

If one person does it, others will justify their own efforts to apply tags to wildlife, and then we get into the legalities of animal cruelty, poaching on conservancy land, and on and on.

It's one thing to crowd source passive eyes spotting for squirrels. It's entirely another to invite people to try and handle them, and even interfere with instruments applied to their body.

Volunteers can vary in their abilities to detect squirrels

Squirrels can vary in their propensity in showing themselves based on weather and more

Squirrels can move between these areas, leading to double-counting

Baby and old squirrels might not even be visible

However, the squirrels in Central Park, were deliberately introduced.

It's unclear whether they were absent from Manhattan naturally, or whether they were extirpated due to urbanization, and the re-introduced later.

And about the invasive status of the grey squirrel in Britain, it's sad that they were deliberately released in Britain, because it's not as if they swam across the Atlantic or hopped a freighter.

Now you guys are fighting an extermination campaign with all the regrettable suffering it causes to both squirrels and humans.

1: The Urbanization of the Eastern Gray Squirrel in the United States Etienne Benson J Am Hist (2013) 100 (3): 691-710.