Wednesday, June 18, 2008

There Goes the Neighborhood

I originally started putting this together in late April, but left it incomplete until now. With all of my recent "neighborhood" talk I thought this one's time has come - what happens when your neighborhood attracts "undesirables."

Originally from 26 April 2008
I mentioned Brown-headed Cowbirds in a recent post as their frequency of sightings reaches its spring peak in our neighborhood, but I left it at merely commenting on their looks. I'll venture that there are others, maybe even a silent majority, that find the rich brown and lustrous black subtly stunning, but most don't discuss cowbirds unless they are racing to the reasons to hate them.

Cowbirds may be the most vilified bird in North America. Every breeding season you'll find anti-cowbird rants as they make their annual rounds on the Internet, a digital harbinger of spring on par with the noticable increase in posts to birding listserves.


Why hate cowbirds? Easy. They're brood parasites, meaning they're pretty lax in the parental care department. They don't bother with the whole nest building, incubation, or nestling feeding scene. They don't provide care for them once they fledge. Those activities are pretty costly energy expenditures, so they lay their eggs in active nests built by another species and let the "host" parents do the child rearing. If your goal is to simply spread your genes, what better way than to lay all that care and investment on surrogates who'll do it for you? Very productive for the cowbird, but with a potential serious downside for many host species, which usually fledge fewer young, if any at all.

The female cowbird may even eject a host egg from the nest when she deposits hers, and the cowbird nestling(s) will typically hatch sooner and grow faster, outcompeting its nestmates for food. Even if the host's nestlings don't starve in the nest, they typically fledge in such poor condition the odds of survival are significantly stacked against them.


It's a pretty blunt strategy, and clearly, it works. Estimates of their population range from 20 to 40 million birds across North America, where they survive, and thrive, from central Mexico to southern Canada. Couple that with the knowledge that cowbird parasitism is listed as a influential factors in the decline of the endangered Kirtland's Warbler in Michigan and Black-capped Vireo in Oklahoma and Texas and you've got to ask, "so, what's not to hate?"

Well, in my estimation, their breeding strategy is not exactly the problem. Species that evolved with cowbirds through the millenia have learned how to deal with cowbird parasitism. They usually recognize a cowbird egg in their nest, eject it, or scrap everything they've done and start over, building a new nest right over the old eggs.

Agonistic behavior: one male "bowing" to the other to show dominance.

It's the species that have only recently encountered cowbirds that are in trouble, the species that have no history with them. These are typically neotropical migrants who inhabit large, unbroken tracts of forest where cowbirds did not historically tread. Now that the forests have been so fragmented the cowbirds are able to penetrate and exploit these naive forest-dwelling birds. Layer the parasitism with additional pressures such as loss of habitat, increased nest predation, pesticide applications, and possibly factors not yet recognized, and you've got a recipe for reproductive unsuccess.

Is it fair to hate the native cowbird for an ingrained behavior, coded in its genes, that's evolved over thousands of generations? That individual under your feeder, or displaying in the bare-limbed tree, or chasing that Yellow Warbler through the foliage, is not consciously scheming, it's merely doing what it does. Cowbirds do what cowbirds do, we've just enabled them to do it more proficiently, and to exploit species that don't know how to react.


And given that, I don't hate the cowbirds, I hate the fact we humans have so drastically upset the system. Now we're in the unenviable position of attempting to manage that system to return some sort of balance, which always seems to muck things up even more. One thing I've learned in our small scale attempts to manage our "neighborhood," meaning our yard: once you monkey with it, you've got to keep at it, and it will be years (if not longer) to evaluate your success.

"Thoreau says 'give me a wildness no civilization can endure.' That's clearly not difficult to find. It is harder to imagine a civilization that wildness can endure, yet this is just what we must try to do. Wildness is not just the 'preservation of the world,' it is the world."
-- Gary Snyder

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Won't You Be My Nieghbor?

The most surprising addition to our neighborhood was not a young couple moving in near the house, it was a young couple moving in on the house. Specifically, a pair of Eastern Phoebes built a nest on top of a remnant piece of a mud dauber nest, high up on the outside garage wall, but within a few feet of our kitchen window.

The nest is within a few inches of the ceiling making it impossible
to check the eggs. She's incubating, so we know they're in there!


Too keep disturbance to a minimum we use the garage door as little as possible, but we do stare out the kitchen window periodically to watch the female incubate. In fact, if you look carefully in the above image you'll see one of our household is watching. Here's an inside shot of the voyeur.

Tazzie, short for "Tasmanian Devil," which barely begins to
describe him, spends the bulk of his time monitoring the nest. As an
indoor cat, this is the closest he'll get to actually earning his dinner.


The phoebe parents let us know how they feel if we do use the garage door. They let us know how they feel a lot. The only time I brought a ladder over to photograph the nestlings one of the parents nicked the back of my head with a wing. I took a couple quick shots and I haven't been back, why stress them more than necessary? OK, to be honest, I thought it would be a bit embarrassing to explain to the doctor a bird weighing less than 20 grams knocked me off a ladder.

"I swear, doc, first I kept hearing their incessant chipping . . .


. . . then it got quiet, too quiet. When I looked over my shoulder I saw I was getting the avian version of the stink eye . . .


. . . and that's when they attacked! Just like the Hitchcock film, for sure!"

video

I didn't get footage of them attacking me, but here's a typical scene when opening the garage door. We've yielded use of our outdoor furniture to them for now, but we're hoping we can resume eating outside soon.



And here's what it's all about: the young-un's. This was taken a couple of days before they fledged, they're probably about 14 days old here. I couldn't tell you how many were in there, but my best estimate is four. They fledged last week, either the 10th or 11th, and haven't seen them since. We've seen the parents a couple of times in the yard, but no sign of the fledgies.

Interestingly, one of the parents has been returning to the nest this week, as though it left something behind. The nest is empty, I checked shortly after they fledged and there's not even an unhatched egg in there.

Phoebes are typically double-brooded, and maybe it's not too early to be thinking about a second nest already. It turns out they will reuse an existing nest; one study showed more than half of old phoebe nests (those present before the nesting season started) were used. The jury is still out on why, perhaps the energy savings in building a new one transfers into larger clutches (as postulated by some researchers), though another study challenged this idea as "reworked" nests did not yield more offspring.

Regardless of why, they seem to be gearing up for round two. I guess we won't be getting our patio back for another month or more, though it's worth the sacrifice!

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Saturday, June 7, 2008

Neighbors

Back in 2002, when we first moved into our new place, we were curious about our neighbors. We didn't really have many "wild" ones, and I don't exactly mean the Dan Ackroyd character John Belushi encountered in "Neighbors." (Personal trivia: that was the first "R" rated movie I ever saw in a theater). No, I mean the wildlife that would be sharing our four acres.

A relatively-recent shot of our place, though some
recent landscaping isn't represented.


The aerial photo, which is facing due west, shows the overall features: open lawn, wooded areas, a pond. When we first toured the house the majority was lawn. If I were a golfer it would probably would have been pretty fun. Alas, or fortunately, neither of us hits the links, and we don't like a lot of lawn. Ever since we moved in everything in the "back half" (would that have been the "back nine?"), or western half, has been allowed to grow. It's developing into a grassy, shrubby area with way too many invasive plants, like Autumn Olive, Japanese Knotweed, Garlic Mustard, Rosa mulitflora, Crown Vetch, and probably more that I'm afraid to identify right now.

Our benign neglect has brought in some wonderful residents, too many to display here, so here are a couple from the past week.

A Green Frog, clearly a male based on the size of the tympanum and the
bright yellow throat, quietly hanging out among the cattails.


At first the half-acre pond was fairly open, only a few cattails grew in one corner of the pond and only Crown Vetch adorned the banks. The only residents were six or seven Koi and a mess 0' catfish. In the intervening years the cattails have expanded quite a bit and we've been planting a few native plants and shrubs around the pond: Cardinal Flower, Blue Flag, Marsh Marigold, Buttonbush, and Swamp Azalea now adorn the edges, hopefully attracting hummingbirds, butterflies, and other insects.

A Twelve-spotted Skimmer (yes, I counted) sits
and waits on an old cattail stalk.


Green Darners, Widow Skimmers, bluets, and other odonates like to perch on the new vegetation, and several amphibians are now resident in our backyard. We mostly hear them at night, the piercing calls of Spring Peepers starting in mid-March, the "jug-o-rum" of the bullfrogs (apparently the Parrotheads of the bunch), the drawn-out trilling American Toads, the loose banjo string twang of the Green Frog, and the quick, Red-bellied Woodpecker-like trill of the Gray Treefrog. In the evenings we say they serenade us to sleep, during bleary-eyed mornings we complain the miserable creatures kept us up all night.

We uncovered this young toad while sorting through a pile of
rocks. We leave piles here-and-there hoping to provide shelter
for them; it's heartening to know we're sometimes successful
.

The new house we added in the middle of the pond, and by "middle" I mean off to one side where it was shallow enough to wade out and mount it, was meant for waterfowl (Wood Duck, Hooded Merganser) or a small owl (screech-owl, saw-whet). I had small hopes for ducks and near non-existent expectations for an owl. After all was said and done we figured we'd be lucky if wasps found it appealing. We were confident squirrels couldn't take it over.

Not whom we expected, but the tenet sits on
her stoop and keeps an eye on her questionable
neighbors. What's that, we're the questionable ones?


As Reina and I explored late spring around our "loop" we noticed what looked like a head sticking out, so I snapped a few pictures (bins were left on the kitchen counter). We assumed it was a Tree Swallow since we saw them checking out the box earlier in the spring, but then they disappeared. Only recently have we seen a couple foraging around the pond quite a bit this season, more than in past years, but it wasn't until we looked on the computer that we saw it wasn't just a head. The bird was perched in the entrance hole. Apparently it is a bit large for what they require, but clearly it's suiting their needs. We're ecstatic someone saw the box fit for their needs.

Stay tuned for an introduction to our next-door neighbors, a couple we never saw coming!
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