count that Grebe!
There's a Simpsons episode that involves birdwatchers, and has the line: "You cannot count birds you've seen at the zoo, on stamps or in dreams." That's a good rule, but for most other cases a common saying among birders is, "you keep your own list". Unless you're in a competition, like a Big Year, what birds you count is completely up to you.
For competitive purposes, the rules can be more complicated. Was that bird just released into the wild after being rehabbed? Did it escape from a pet owner? Did it hitch a ride on a ship from Bermuda? These are all cases where you're not supposed to count the bird.
A Red-Necked Grebe showed up last Wednesday on the Reservoir in Central Park. That's a very nice bird for Manhattan. There was one who stayed for a month or so in March/April of 2014, and a handful of other sightings. I went out to see it Thursday morning and got a decent look. It was hunting happily. Its dives were interesting to watch; it levered itself up out of the water and plunged in with surprisingly little splash. That's different from (for example) a Pied-Billed Grebe, which just kind of ducks quietly underwater with little fuss.
A lucky shot--too blurry but I like it. Look at those feet!
This bird, it turns out, was released by the Wild Bird Fund earlier on Wednesday. It had been picked up in, I think, Brooklyn (where it's slightly more usual) with some injury, and rehabilitated by the WBF, who usually release their patients in Central Park. I thought the usually released waterfowl in the Lake, though because getting to the water's edge at the Reservoir involves going over a fence.
Look at the photo of the bird diving--see how far back its feet are? Grebes (and loons) have their feet way back on their body. That makes them faster underwater, but it also makes them very awkward on land. If you're releasing one, you probably want to put it right in the water rather than make it drag itself down a bank.
Anyway, there has been some discussion about whether people are counting the Grebe on their New York County lists. I am, myself.
Meanwhile in Berks County Pennsylvania, a bird called a Black-Backed Oriole has been seen around a feeder in a town called Sinking Spring. This is really problematic for people who keep lists, because that's a bird from central Mexico that doesn't migrate any distance. There's never been a sighting north of the border---well, that's not right. There's never been a sighting north of the border that a state records committee has decided was a real vagrant. There was one in San Diego, California that they eventually--after a couple of years--decided must be an escapee. It summered there twice, then showed up in January, and that apparently decided them against it because reasons.
So, again, except for people doing competitive listing, it doesn't matter. Go chase the bird if you chase rare birds, it's undoubtedly a hell of thing to see. I'm fine if they count it, too; everyone keeps their own list. I will say that if the records committee accepts this, I'm going to start counting this one:
That's a Yellow-Fronted Canary that showed up one Fall, foraging with Sparrows on the great Hill in Central Park. That's an impossible vagrant, and though it's on my eBird list (eBird doesn't care where a bird came from; you see it, it's on the list) I don't count it. But it's not much more unlikely as a vagrant than that Oriole, in my opinion.
I think I only count one bird on my own list that wouldn't normally be countable in competition.
I'm a wild one!
This European Goldfinch wintered in Central Park twice, 2011-12 and 2012-13. It flocked with House Finches until it started singing, at which point they drove it away as a dirty foreigner. Then it hung out with American Goldfinches, who (being real Americans) didn't care where he came from. He left Central Park when they left. (American Goldfinches mostly don't summer in the Park.)
I didn't see any specific evidence that he was an escapee, so I counted him. They're migratory; vagrancy is not impossible. I think they're even countable in some states farther north.
The European Goldfinch didn't come back after the second summer. That's probably not a good sign for his well-being, but who knows? Anyway, he's on my list.