American Birding Podcast



Fuzzy Math

A few weeks ago, my wife and kids and I spent a lazy Sunday afternoon at City Park in downtown Denver, Colorado. Our excursion wasn’t primarily for birding, but that didn’t stop me from noticing the park’s birdlife. Some of the birds I saw that afternoon included: 

  • 01 MERL4A handsome Merlin perched atop a tall cottonwood; and a lovely basic adult Bonaparte’s Gull flying just above the surface of one of the ponds in the park. Those are nice birds! I don’t mean they’re especially rare. Rather, I mean they’re, well, nice. They’re beautiful. I love seeing Merlins and Bonaparte’s Gulls. (Right: Merlin. Photo by Bill Schmoker.)
  • Nine Black-billed Magpies and approximately 90 House Sparrows. Magpies are common as dirt in the Denver metro area, but one never tires of studying these fascinating creatures. And I confess to a certain amount of fondness for House Sparrows, those exemplars of sociableness.
  • Gazillions of geese, of course. Nearly all were “white-cheeked geese” (Canada and Cackling geese), but I did manage to pick out a single adult Snow Goose in the great anserine throng.
  • One drake Barrow’s Goldeneye and a hrota Brant. Great birds! Barrow’s is a choice bird—rare but annual—in the Denver metro area, and Brant is a rarity anywhere in Colorado.
  • One Graylag Goose and three Indian Peafowl.


If you know Denver, then you know that City Park is home to the Denver Zoo. The peafowl and the Graylag Goose don’t “count.” Neither do the Barrow’s Goldeneye and Brant, because both were on a pond within the zoo’s perimeter. Meanwhile, the other species—Merlin and Bonaparte’s Gull, House Sparrow and Black-billed Magpie, and all those “white-cheeked geese”—were legit. They’re wild; they got there on their own; they “count.”

Actually, it’s not nearly so straightforward as I’ve just laid it out.

First off, what about the Snow Goose? We saw the bird in the zoo, milling around with Canada Geese. It was banded, but so were many of the Canada Geese. I couldn’t make out the Snow Goose’s band. Was it tagged here in the zoo, or was it banded by Canadian Wildlife Service biologists thousands of miles to the north? In other words, did the Snow Goose “count”? I just don’t know.

02 HOSP1 Now what about the House Sparrows? I’m practically certain the Denver Zoo doesn’t keep House Sparrows. But the House Sparrows see it differently. They consider themselves to be as much a part of the zoo’s fauna as the reticulated giraffes and Malayan tapirs. Indeed, we saw House Sparrows tending apparent nests in both the giraffe and tapir exhibits—in the indoor areas of those exhibits, no less. (Left: House Sparrows. Photo by Bill Schmoker.)

Do the House Sparrows “count”? I think most birders would say so—despite their heavy reliance on the manure, straw, and indoor roost sites at the Denver Zoo.

What about the Merlin? Surely it “counts”! Perhaps, but consider the following: In my experience, City Park is the most reliable place in Colorado to find Merlins. I’m suspect that’s because City Park—and the Denver Zoo in particular—is overrun with House Sparrows. I believe those sparrows—born and reared in the zoo—sustain the park's wintering Merlins. Indeed, the Merlin atop that cottonwood was devouring a passerine that I’m almost certain was a House Sparrow.

03 Malayan Tapir Dave Parsons If you want to see Merlins, House Sparrows, and Malayan tapirs, go to City Park. All three species prosper because of human activities at the Denver Zoo. (Right: Malayan tapir. Photo by Dave Parsons.)

Oh, all right, but can we at least “count” the Bonaparte’s Gull? It was flying around a pond outside the zoo’s perimeter. Ah, but that’s an artificial pond full of non-native fish and other aquatic organisms—among them the Graylag Goose. That’s right, the Graylag Goose wasn’t in the zoo; it was out in City Park, out in the “wild.” Indeed, I’ve been noticing Graylag Geese for several years now at City Park. They’re undeniably of non-native origin, but they seem to be as capable of survival on their own as the other denizens of City Park: the “white-cheeked geese” and Black-billed Magpies, the Merlin and Bonaparte’s Gull, and so forth. If those human-assisted species “count,” why don’t the Graylag Geese of City Park?

Moving right along, can we at least agree that the Indian Peafowl emphatically don’t “count”? That’s tricky, I have to say. Over the past several years, my kids and I have been noticing that peafowl breed in the zoo—not in cages or other exhibits, but rather at their own “natural” nest sites. Their nests are well hidden. If you do find one, and if you get too close, the adults will repel you. Yes, their nests are within the zoo’s perimeter, but that’s true as well of such zoo nesters as Northern Flickers and American Robins—native species that surely “count” for any birder’s checklist.

I know! I know what to do! Just don’t go birding in City Park! Such desiderata as Merlins and Bonaparte’s Gulls can be found elsewhere in the Front Range region—in places where you don’t have to fret about about feral Graylag Geese and Indian Peafowl; where you don’t have to ponder the native Black-billed Magpies and established House Sparrows that flourish around the Denver Zoo’s outbuildings and manure piles. Just focus on natural habitats, and all will be well.

Problem is, that strategy doesn’t really work. Let me explain by way of a personal odyssey of mine.

The first few years I lived in Boulder County, Colorado, I was baffled by a wild crowing sound I sometimes heard at dawn. What was it? A raptor? Possibly some large aquatic species? Maybe a terrestrial game bird?

Eventually, I figured it out: The source of that sound is the Indian Peafowl.

Click hear to listen to chorusing Indian Peafowl; recording by Gopinath Sricandane.

Peafowl are surprisingly widespread, I have found, in Boulder County. For folks who know the county, I can tell you that I’ve heard them recently at Walden Ponds, at Ish Reservoir, and along Apple Valley Road. Typically, I hear them well away from farms and other human residences. They’re just out there, out in the wild, doing their thing. Do the peafowl repair at night to roosts near barns and feedlots? They may well. That’s the avian way, after all: Think of all the American Kestrels, Barn Owls, and so forth that do the same thing.

05 Peacocks3 A little while ago, I added Indian Peafowl to my Boulder County lifelist. The birds are here. They’re meaningfully present in the county. They’re part of the biological and cultural landscape of Boulder County. As far as I'm concerned, they count.

(Left: These Indian Peafowl are part of a semi-feral population that appears to be widespread and possibly expanding in Boulder County, Colorado. Photo by Bill Schmoker.)