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Monday, June 11, 2012

The British Invasion and Avian Discrimination: Swallowing Problems in the Valley…

Dad and Jrs.This time of the year when we were kids it seems like we’d always come across some baby bird that had tumbled from its nest and was foundering in the grass or weeds. Even then we were keen to the rule (long since disproved) that if you tried to return the chick to the nest, its mother would reject it because of the foreign odor on the nestling. The little thing was most certainly doomed unless Mother Nature’s little helpers came to its rescue, took it “under their wings,” assumed the role of surrogate parents. We’d spring into action; scavenge a cardboard box for a nest; clean rags for nesting material and warmth; and—the key to the rescue—nourishment; if a thing eats, it’s bound to live. For lack of crucial parental gruel—regurgitated insects, worms, grain—we would substitute what worked for human infants: dry baby cereal moistened with milk. In those days our pantry always included this staple; in our large family it seemed there was always an infant about. (And for the sake of nostalgia, we non-infants in the household might serve our own selves a bowl—heavily sugared, of course.) We would load the mushy substance into a medicine dropper and proceed to “inject” (or “drown”) the hapless fledgling with pabulum. With the exception of five magpie chicks we unwittingly adopted, all of which proved to be feathered alimentary canals, the morning after our youthful intensive care we would without fail awake to find a pitiful little corpse stiffened in its rag nest. Then the brief funeral and on with the day….

There is something satisfying about reaching out to a wild thing, connecting with it in some way. Perhaps it has something to do with a sense of kinship, or desire, to affirm our place in the natural world. Without spending an hour on a psychiatrist’s couch, that’s my amateur explanation of why I was determined to have a pair of tree swallows nest in a nest box I built especially for them. Years ago we had a pair of tree swallows nest in a birdhouse gourd I had grown in the garden the summer before. Shortly after I hung the gourd on the grape arbor, the swallows moved in and began the nesting process. As the summer progressed, we would spend some time each evening watching them come and go: nesting material first, then the male feeding the female while she sat the eggs, both sharing foraging flights for bugs to feed the hatchlings, finally the miniature heads bobbing about the entrance impatiently awaiting their next feeding. The foraging continued into the twilight of the evening, the parents working in tandem, each in turn swooping off into the dusk and returning to deposit its latest catch of mosquitoes and gnats into the clamoring mouths.

The chicks never fledged. They grew bolder by the day and then, as I feared, the inevitable happened. One of the chicks toppled from the gourd. I found the struggling bird on the ground beneath and unwittingly returned it to the nest. Two days later I noticed the feeding activity had ceased; only the female returned to the nest that day, peered inside and flew off. The next day I noticed flies flitting in and out of the gourd and went to investigate. I found the chicks dead, their swollen little bodies crawling with mites. Was I responsible for their tragic demise? Had the mites infested the fallen chick and by restoring it to the nest I had infected its siblings? Were the parents in some way responsible? Did the gourd’s proximity to the vine’s foliage contribute to their deaths? I never did discover the cause. Later that day the female, prompted by her maternal instinct--or hope-- returned one last time, perched on the nest’s entrance, and peered inside. Finding nothing stirring, she flew off. We never saw her again that summer and felt a twinge of sadness whenever we glanced at the abandoned gourd. For a while our evenings were not quite the same. Tree swallows have only one brood a season; we knew the pair wouldn’t return to the gourd  for a second settin.’

During the winter I consulted references books on nest boxes for cavity nesting birds, especially tree swallows. The source I chose specified the following:

Interior floor size—5”x 5”

Height of box—10-12”

Entrance hole diameter—1 1/2”

Mounting height of box—10-12’ from the ground

A photo of a nest box showed the entrance hole at least two-thirds up the face of the nest. This got me to thinking about the gourd failure: perhaps the cavity was too shallow, allowing the overeager chicks to tumble out before they were ready to fledge. A deeper cavity would prevent such premature adventures. Using rough cedar fence rails for lumber, I followed the above specs and constructed the nest. The roof I hinged so I could access the cavity for cleaning. The sloping top had an inch and a half overhang for rain protection and shade. I installed two brass hooks to latch the roof to the nest. Before I cut the nest box entrance, I consulted authorities on the hole’s diameter. Everyone I talked to said an inch and a half diameter would allow larger birds access, especially English sparrows. They recommended I reduce the hole to one inch and make it oblong instead of circular. I cut a round hole one inch in diameter in the face of the box and left it at that.

On a sunny spring day usually mid-April the tree swallows arrive on the place and immediately examine the premises for potential nesting sites. A day or so later after their first visit I climbed a ladder to the peak of our storage shed (at a height a half dozen feet higher than the specs required) and installed the new cedar nest box just under the eaves. Hardly two hours later the swallows did a fly-by, kicking the tires, so to speak. The male swooped up, landed on the box, peered in two or three times, and departed. Every three or four hours they’d return and repeat their inspection.

A couple days later the male attempted to enter the nest box (the male apparently must give an “all clear” before his mate crosses the threshold herself). Head inside but no further. Time and again he’d struggle to gain entrance but could go no further than his shoulders. For its size a tree swallow is a broad shouldered little bird. I determined the entrance must be too small, took the box down and enlarged the hole. This time I tried to give it an oblong shape. Up the ladder again. Hardly had my feet touched ground when Mr. flew to the nest, looked in a time or two, teetered on the lip of the hole and disappeared inside. Success at last, or so I thought.

“Bully,” as the British say, and so right they are: the English sparrow is just that, a backyard bully, a dowdy thug that is as aggressive and tenacious as a pit bull. Its nesting instinct is more powerful than the Octomom’s (three to five broods a year!). When the Brit takes a liking to a nesting site, it will have it or else, mercilessly harass any other tenant, and drive it from the premises. A few years back we installed a stylish high rise bird condominium, hoping to attract a respectable clientele, birds with both class and color. By the end of the summer the “Engs,” (our family’s pejorative for this avian pest) had trashed the condo, turned it into a Dickensian tenement.Sparrow Heights  To discourage their presence on the property, I boarded up the entrance holes. Today Sparrow Heights stands like an abandoned tenement row after the Watts’ neighborhood riots.

Yes, I enlarged the entrance…and the modification did not go unnoticed by the Engs. A pair started their bullying ways almost immediately, perching on the shed roof or carport, even settling on top of the occupied nest box, insinuating themselves on the swallow tenants. The Engs work in tandem…like Bonny and Clyde without Tommy guns. For a few days the swallow male defended the nest box with the help of his mate. In the evening both would fly away to roost elsewhere during the night. Early in the morning they would return and defend their stake in the nest box. The Engs would bide their time, making periodic incursions in the swallows’ space, just waiting, waiting…. One evening not a half hour after the swallows left for night, the sparrows moved in. Come morning the swallows found their nest occupied. Possession is nine-tenths of the law, and the Engs now ruled the roost. I would take my air rifle and rattle a bb off the nest, chase them out and away. Even though the bullies had left the premises, for some reason the swallows were reluctant to reclaim the nest box. They would hover around the entrance, briefly land on the face of the nest, but refused to enter the box. If I had errands to run or indoor chores to do, the Engs would return and commandeer the nest box again. The swallows would leave for the night but would return and perch on our t.v. antennae, waiting for who knows what to happen. This scenario repeated for two or three days. I began to fear that the swallows would give up and nest somewhere else. Not only had the sparrows hauled in nesting material, but I suspected they had left a “scent fence,” a territorial odor that kept the swallows at bay. Up the ladder again. Down with the box. I soaked it in a bucket of rainwater for a day, let the box dry and air out for a week, back up the ladder, rehung it again. 

Now I know you’re probably thinking I had plenty more pressing things to attend to and you’d be right, but this man was NOT about to be bullied by a pair of frumpy Engs. For the next three weeks I was up and down the ladder at least two more times. But for bit of luck and poor aim resulting in sparrowcide, who knows how long I would have had to arbitrate the nest box issue. Unfortunately the male Eng got in the way of an errant bb and that was that. The swallow pair moved in immediately; they didn’t even bother to attend the funeral. The rest of the nesting cycle seemed routine; however, one of the chicks fledged too soon. I found it dead in the weeds nearby. As far as I know the remaining hatchling fledged successfully the very next day. Their nesting ordeal finished for the season, the pair left in the company of the youngster, and the nest box was abandoned.

As if I hadn’t spent considerable time with my swallowing problem already, I kept a journal of the swallow/Eng ordeal, keeping a daily account of both species’ behaviors. When the swallows came back this spring, I consulted last year’s experience and found it was “pete and repeat” this season with the sparrows. Up and down the ladder; rinsing out the nestbox. The second time I rehung the box, I thought my efforts would pay off. The swallows took over their nest, but four days later as soon as they flew off to their nightly roosting site, a pair of Engs moved in, carrying nesting material with them. “Ok, you little buggers, go for it,” I said. “You can do your dirty work for a week and then down comes your home and all its contents.” Five days later I climbed the ladder again. When I lifted the roof of the box, I found a complete nest and four eggs. No wonder the countryside is overrun with the tenacious little fluff devils. I dumped the contents, eggs and all, over the fence and submerged the purged nest box in the rain barrel once more. In the meantime the tree swallows remained ever hopeful, faithfully returning to the t.v. antenna each morning, periodically fluttering around their nesting site as if expecting the box to pop out of the side of the shed for them. A week later…up the ladder again.

At this point the pair are at home in the box as if nothing had happened. Currently they have chicks to feed and are foraging for bugs (a single swallow can consume two hundred or so insects in a single day) to feed their young. Both parents are hard at work: as soon as one arrives at the nest, the other spurts out and takes its turn. Back and forth they fly from dawn to twilight.Swallow mom

What I have learned from my swallowing experience is apparently the one-brood species has a certain window of time for nest building. During this period they instinctively know it’s do or die if they want to raise a family that season. Once this “zero hour” is reached, they will defend their nesting site aggressively, doing battle with Engs, starlings, or any other bird that enters their space. My last year’s journal has been helpful with the timeline:

May 15-17—Female began carrying in nesting material.

May 18—Nest building continues…

May 20—Noticed mating activity…

May 22—More mating activity. Female is spending more time in the nest? Eggs, perhaps?

June 1—The female is brooding; the male feeds her periodically…

June 16—Chicks have hatched. Both parents are foraging for bugs and feeding their babies…

June 25—Miniature heads appear in the nest entrance…

June 29—Two heads always at the door, one larger than the other, the larger is just poised to fledge…

July 1—The chicks have apparently fledged. No sign of them anywhere. The male visited the nest twice, checked inside, and flew off. Probably won’t see anymore swallow activity at the nest until next season. I hope both chicks fledged and are soaring in the Valley with their parents.Feeding time

There you have the swallow season in an “eggshell,” and this one has been almost a mirror image of last’s. But I’m a wiser person now. Next year I’ll wait until mid-May to struggle up the ladder: hopefully, only one round trip this time. The rungs seem to get farther apart each year, the height more dizzying. After all, I’m not the fledgling I used to be.Waiting for Mrs.

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