"In the spring a young man's fancy lightly turns to thoughts of love." So wrote Alfred, Lord Tennyson--poet laureate of the United Kingdom during the Victorian era. He was right, except for one thing: The fancy of most young men we know turns HEAVILY to love--not lightly--when the calendar flips from winter to spring, and they may have more than platonic relationships on their minds. We don't suppose other organisms think about "love" when spring is in the air, but if observations this week at Hilton Pond Center are any indication the birds and the bees and even the trees are at least intent on reproduction and passing their genes to the next generation.

The first sign that spring hormones are still raging came when we almost stepped on a female Painted Turtle, Chrysemys picta, not 30 feet outside our office window in the Center's old farmhouse. As we were checking mist nets for birds, we happened to look down and noticed the dark, smooth-shelled reptile--with a muddy hole in the ground at the posterior end of her carapace. This turtle was hard at work; she'd already moistened and softened hard clay soil with her urine and excavated a vase-shaped cavity in which we already could see one oval-shaped white egg (above)--still glistening from just having passed through her cloaca.

We slowly backed off and went inside to get our camera, returning to find the turtle intent on finishing her clutch. (We're always careful when we encounter nesting turtles; too much activity can cause them to abandon egg-laying and retreat to the safety of the pond.) We took a few quick exposures of the scene and slipped away again to observe through office window. We're happy to report the gravid female laid at least three more eggs before covering the hole with earth that she flattened out, sliding back and forth over it with her lower shell. We've got the spot marked and look forward to seeing a new generation of little Painted Turtlets emerging from it in 60 days or so.

Another sign spring reproductive activities are still underway came as we went out to check the morning mail one day this week. Years ago we mounted a bluebird box on a gatepost at the end of the Center's driveway. It's not unusual for Carolina Chickadees to use this box early in the season and raise their brood, after which we throw out the mossy, messy old chickadee nest and give Eastern Bluebirds a chance to move in. We suspect it is always the same female bluebird that had used the box in recent springs, based on her distinctive behavior of exploding from the nest box any time we walk past--or even when we're in a vehicle and slow down to turn into the driveway. This jumpy bluebird laid one egg a few weeks ago and then stopped but seems to have cranked up her ovaries again. This week she was sitting on six shiny sky blue eggs (above), each containing her genes and those of her mate.

Although we didn't capture the skittish female bluebird from the driveway nest box, we know from experience a close examination of her external anatomy would have revealed an interesting phenomenon--as shown by a breeding female Northern Cardinal (above) we DID catch. The cardinal's leg already bore an old, worn aluminum band that indicated she had been around for a while so we figured she, too, was a local breeder. We jotted down her band number and blew gently on her belly feathers, exposing an incubation patch--tell-tale proof she was nesting at Hilton Pond Center. The incubation patch--sometimes called a "brood patch"--is an expanse of skin that becomes denuded when female birds come into breeding condition. Feathers are lost primarily due to hormonal changes, although in some species the female may pluck them out and use them to line the nest. Since feathers are insulation, losing them from the belly area means the incubating mother bird's body heat is transmitted more efficiently to eggs and chicks. What's most phenomenal, however, is that the abdomen not only gets naked, it also gets edematous (collects fluid under the wrinkly skin) and becomes vascularized (more blood vessels develop and bring additional body heat). In effect, the incubation patch is just like an old-fashioned hot water bottle--one that maximizes the possibility the cardinal's progeny will survive.

Male birds also show external changes during the breeding season. In a few species--Downy Woodpeckers and Great Crested Flycatchers, among others--males also form brood patches and share incubation duties with their mates, but these are rare exceptions. What's far more common in the male is development of a cloacal protuberance, a noticeable swelling of the cloaca itself. Male birds have it tough in lots of ways, not the least of which is that their testes are internal--an adaptation that actually helps with streamlining during flight. The problem comes in that a bird's body temperature is about 105 degrees and sperm--formed within the testes deep inside his ultra-warm body cavity--die at about 95 degrees or so. Fortunately for the male's future offspring, mature sperm collect around the cloaca close to the surface, forming the cloacal protuberance; there the sperm are cool enough and perfectly situated for quick transfer to the female's receptive cloacal opening during copulation. Some male birds have almost undetectable cloacal protuberances that are surprisingly large in such diverse species as Indigo Buntings, American Robins, Chipping Sparrows, and Eastern Towhees (above). The photo also shows a ring of longish feathers around the cloacal opening that likely function to funnel sperm from male to female, ensuring their genes are passed on.

There's no question our local Ruby-throated Hummingbirds also are in the midst of spring breeding and gene-passing activities, and sometime next month we'll likely trap or net our initial hummer fledgling of 2011. There will be little doubt that first young hummingbird--just learning to fly and feed--couldn't have come very far. Despite "incontrovertible" evidence hummingbirds breed around Hilton Pond, in 30 years we have yet to find one of their nests, but one female we caught this week had a cloaca so distended (above) she must have deposited her most recent egg someplace very close by. We've always thought it amazing a hummingbird with such a small external orifice can lay an egg the size of a gourmet jelly bean. In reality, though, we suppose that's no more phenomenal than an eight-to-ten-pound human fetus passing through its mother's birth canal.

Last week we wrote about an American Goldfinch banded in January 2009 at Hilton Pond Center that was recaptured and released a year later (March 2010) by Jim Gruber--a bander at Foreman's Branch Bird Observatory on the eastern shore of Maryland, near Chestertown (see map above). Based on a note we received this week from the federal Bird Banding Laboratory, it appears we reported the Maryland encounter a week too soon. Why? Well, had we waited until this week we could have announced Jim Gruber actually recaptured TWO of our goldfinches, the latest a second-year female banded at the Center on 19 April of this year and caught again at Chestertown just a month later on 22 May. We're not sure what the chances are of banding two American Goldfinches at the same Carolina Piedmont site and then having them show up more than 400 miles away at the same research station in Maryland, but those odds are probably pretty slim.