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MORE SPRING MISCELLANY:
WHITE OAK & PURPLE FINCHES

This time of year it's always easy at Hilton Pond Center to find something to photograph and write about. Whether it's flowers blooming, birds nesting, or insects emerging, things are really beginning to bustle as winter blends with spring. The transition period is always interesting--we still see a few Purple Finches even as Ruby-throated Hummingbirds have started arriving from the tropics--and thes seasonal swing often leaves us with several topics to discuss.

All text, maps, charts & photos © Hilton Pond Center

One piece of unfinished business pertains to the massive White Oak, Quercus alba, that towers over the east bank of Hilton Pond. During a storm last summer we were at our office window when an ear-shattering crack of thunder shook the glass. We suspected lighting had struck very near--the thunderclap and electrical flash had been simultaneous--and the next day discovered our tall White Oak had been the target (see The Incredible Power of Split-second Lightning). One afternoon this week, as many local trees were bearing leaves or flowers, the big oak stood nearly naked against blue sky. So far it has no new foliage, and several large limbs are still holding dead leaves from 2005. Dead leaves on an oak in early spring might not seem significant--they're scarcely noticeable in the upper right quadrant of the photo above--but their presence is definitely NOT good. Killed by a sudden powerful surge of electricity, these leaves are a sure sign the limbs bearing them also got fried when lightning hit. We'll be keeping a close eye on our 125-foot oak for the next few years, especially since a huge lightning scar opened its bark to possible fungal invasion. If this magnificent tree dies it will be a major, major loss to the Center's landscape--to say nothing of having impact on birds and mammals that dine on its acorns each fall.

As noted in this week's introduction, at the end of March 2006 we still have a few Purple Finches--in various shades of raspberry, brown, pink, and gold (above). We did band a Purple Finch at Hilton Pond Center as late as 24 April 1983, but by now the vast majority of these winter visitors have departed for breeding grounds up north. Nonetheless, something we never would have anticipated a decade ago happened on 26 March 2006: It was the day we banded our 1,728th Purple Finch at the Center, meaning that species moved ahead of House Finches as our all-time most commonly banded bird.

House Finches--a species native to the western U.S.--expanded rapidly throughout the East after several pairs were released in New York in 1940-41. Within 40 years or so they were breeding across the Carolinas, and in the "winter" of 1983-84 we banded our all-time high of 976 (see chart above, in which "winter" is defined as the period 1 July through 30 June). House Finches tapered off soon thereafter before reaching an "average high" in the early 1990s, but they have been in relative decline ever since; the decrease may be due to epidemic-level incidences of conjunctivitis, a highly contagious eye disease that can lead to bird death. Unlike House Finches, our Purple Finches appear to be on the increase locally, with Hilton Pond's record high of 1,056 coming in the winter of 2003-04.

According to the chart above, in some years when Purple Finch numbers have been up, so have the numbers for House Finches. But it also looks as if there is an inverse relationship in many winters since 1982-83, with higher numbers of Purple Finches corresponding with lower numbers of House Finches, and--less commonly--vice versa. Do winter populations of Purple Finches (PUFI) and House Finches (HOFI) somehow influence each other, or are they influenced in different ways by their environment?

• PUFI are generally more aggressive than HOFI, and they bite. (In fact, banders call them "Purple Pinches" because they often nip the hand that bands them; HOFI almost never bite--at least not human fingers.) Might PUFI lord over the bounty we offer at Hilton Pond Center and push HOFI to more marginal habitats away from feeders--and our traps?
• Since PUFI appear to be facultative migrants that typically come south only in winters when there's not enough food up north, when they DO arrive do PUFI drive HOFI even further southward than Hilton Pond Center?
• In years when HOFI numbers are up and PUFI numbers are low, is it just because the PUFI didn't migrate south that year?
• In nature, populations of many kinds of animals fluctuate in cyclic ways, often because their food sources are also cyclic. At Hilton Pond, PUFI--especially over the past ten years--seem to be on an every-other-year up-down cycle. What might this indicate?
• Will HOFI populations at Hilton Pond Center continue to decline, and PUFI increase?
• Are the apparent relationships in the chart above real or imagined or just coincidental?

We don't yet have the answers to these questions, and some may be unanswerable. One course of action that could help is to continue banding locally for another 25 years! (We welcome your hypotheses on what may be going on in populations of Purple Finches and House Finches around Hilton Pond.)

And speaking of Purple Finches, we got word from the federal Bird Banding Laboratory about PUFI #1811-40283, which we handled a while ago at Hilton Pond Center. The good news is that this particular individual--banded as a brown bird of unknown age and sex on 13 February 2004--was encountered four months later on 9 June by Millie Pelrine of Monastery, Nova Scotia (see map above). The bad news is that this far-ranging Purple Finch, captured at York SC in a trap baited with sunflower seeds, was recovered 1,275 miles away . . . but only because it had been killed by a free-roaming cat in a devastating end to a very long journey. It's one thing to die in migration because of exhaustion or some other natural cause, but it pains us to think about this little one-ounce finch falling victim to the hunting skills of a non-native feline after flying all that way.

This Purple Finch found in Nova Scotia was the 49th bird banded at Hilton Pond Center to be encountered outside York County SC, and it wasn't the first of our banded birds to be taken by an outdoor "house cat" (see Foreign Encounters Chart). Cats by nature are killers, so please keep your predatory pets indoors. That way, spring--and the other three seasons--can be much happier for long-distance migrant birds and other wildlife in your backyard . . . and beyond!

All text, maps, charts & photos © Hilton Pond Center
Purple Finch background map courtesy Google Earth

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Thanks to the following fine folks for recent gifts in support of Hilton Pond Center for Piedmont Natural History and/or Operation RubyThroat: The Hummingbird Project. Your contributions allow us to continue writing, photographing, and sharing "This Week at Hilton Pond."

Be sure to scroll down for an account of all birds banded or recaptured during the week, plus other nature notes of interest.

"This Week at Hilton Pond" is written & photographed
by Bill Hilton Jr., executive director of
Hilton Pond Center for Piedmont Natural History.

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