Population dynamics

Nature bummin’ with Kirk Gentalen

A raccoon youngster

“Maybe the next column should be about baby birds,” I wondered out loud. “Baby animals would be better,” my son Leif exclaimed. “You are right!” I replied—actual conversation.

The size of the St. George peninsula’s critter population ebbs and flows with changes in season and resource availability. Take the month of May for example. The peninsula sees an uncanny rise in population numbers connected with increases in daily daylight-length and plants making food and turning things green. Through the magic of migration and some hardy overwintering techniques, yards that were quiet and seemingly bare just a few months ago come to life. Literally overnight the peninsula’s population can double in size (songbirds migrate at night), if not by more.

And even though some birds (and insects and mammals, too!) do sit on beaches, the peninsula’s animals are not here to lounge. They are here to mate and raise their young, a constant effort to put their offspring in the best positions to survive. With that in mind, each June the peninsula’s already increased population enjoys a significant bump in numbers with the woods and fields crawling with youngsters.

Mammals that overwinter in St. George start their courtship and mating rituals in winter, before most songbirds arrive or insects wake up. The strategy (and the song) remains the same, though—time your youngster’s food independence (the weaning process) for when food resources are rich and plentiful. The best position for your young to survive, nutritionally speaking.

Lately, we’ve heard talk of foxes carrying young pups across Watts Avenue. Seems a little overprotective, as Watts is not a very dangerous road, but maybe the road wasn’t the danger they were avoiding. Whatever the case, relocation can be a good survival habit. There has also been a group of five young raccoons that have spent quality time in the neighborhood (tip of the hat to the Delaneys for the heads up on this masked crew). To be as active as they were, the raccoons had to be at least 10 weeks old, which puts their birth in the early part of April. With a little more math and a glance at a calendar, we can move further back in time to account for the mother raccoon’s nine-week gestation period. That has us looking at an early February (roughly) successful mating “incident.” Such heat-generating activities during the coldest of winter stretches provided some sweet, fuzzy entertainment in June. What a world! Now, if every pair of raccoons on the peninsula had five young? Well, you can do the math…population explosion!

Catbird chicks

Listening can be a key to finding “baby” birds. Just the other day Leif and I heard the begging cries of nestling birds as a cardinal flew out of one of Suzanne’s shrubs. We put one and four together and figured we’d poke our heads into the canopy and maybe find us some young cardinals! It only took a few moments to locate the nest, complete with four now silent heads pointing up and giving us the “big eye.” Lack of a seed cracking bill and or any sign of the color red tipped us off that this was no cardinal nest. We watched the nest for about a week and as the nestlings developed it became clear this was a gray catbird nest. Even though we kept a close eye on the shrub, never once did we see the adults enter or leave the area. It was a lesson in stealthiness as a good parenting technique. On a personal note, it was also the first active catbird nest I have ever found (thank you cardinal). How many other pairs of birds have sneakily added four young to the peninsula’s critter population?

With any fluid population though, the number of individuals will peak at some point and then begin an inevitable decline. Ducks with young are an observable example of this and repeat trips to watch common eider families at Marshall Point in June had this concept on full display. A female eider averages four or five fledglings per nest (one nest a year) and at Marshall Point (and other locations most certainly) it’s not uncommon to see multiple females bring their young together and form rafts of 15 or more little bobbing duckies. It’s one of those “safety in numbers” things—the best position for your young to survive. Watching this year’s local raft dwindle from 12 to four youngsters (probably less by now) reminds us that numbers don’t provide safety for all and that many species of duck will have multiple young every year for multiple years in order to simply replace themselves.

A small raft of ducklings

The disappearing eider ducklings also remind us that young bald eagles need to eat. Adult bald eagles start sitting on eggs in the heart of winter so their young would be fledging the nest just when ducklings are numerous and ripe for the picking (amongst other food species). Babies being fed babies. Food chain, baby.

I got a lovely text the other day from Brian and Meg (and Alita) from across the road saying a falcon was eating a robin in their backyard. Would I like to come over for a look? (Have I mentioned how much I love the neighborhood?) By the time I got over the Merlin falcon had feathers flying and a sizable pile of discards surrounding the carcass. It dawned on me that the robin which had only moments before became a meal could easily have been a youngster I mentioned in the previous column. Survival instincts were not strong in that one. But a Merlin needs to eat and feed its young, like the fisher, coyotes and owls. Watching a predator at work can be awesome!

Significant parts of local food chains are supplied each year by the failed attempts of animals to replace themselves. While we celebrate youth, rebirth, and new life each spring, soon the glaring and harsh reality that most young will end up in another critters belly becomes clear. It’s beautiful in its own way, of course. The persistence, perseverance, and “never quit” attitude of those animals who watch their young disappear each summer is a marvel as well. Keep trying and spawn ’til you die. It amazes me, the will of instinct. It’s all worth celebrating, all the stages of life.

PHOTOS: Kirk Gentalen

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