Slugs are hermaphroditic, possessing both male and female organs; most species mate, however, with one slug pursuing the slimy trail of another. If a slug is in mating mode, there is a chemical that is present in its slime that conveys this information to other slugs. When two receptive slugs first encounter each other, there can be extensive interaction prior to mating. The pursuer often mouths the tip of the tail of the slug it’s pursuing (see photograph) to confirm that it’s receptive. The pursued slug may shake its tail vigorously to signal that it’s not interested, in which case they go their separate ways. If the leading slug is receptive, however, mating eventually takes place, with sperm being transferred from each slug to the other through penises that extend half the length of their bodies. During this process, the sexual organs are entwined; occasionally, in some species, the organs get stuck. If this happens, one slug gnaws off the other’s penis in a process called apophallation. The penis is not replaced and the slug lives the rest of its life as a female. (The opening you see on the side of the slug is its respiratory opening, or pneumostome.)
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Most of us are familiar with the American toad’s breeding call – a long trill that advertises his presence to potential mates in the area. However, American toads have three other calls, as well. A shortened version of the courtship trill, which sounds like a chirp, is given by male toad with its vocal pouch just slightly inflated. A second, release call, is often heard when a male is clasped by another male. (If you want to hear it, just pick up a male toad during the breeding season – it will vibrate as it chirps right in your hand. The combination of the call and the vibrations usually causes a clasping male to release his grip.) A fourth call, which has been recorded in the lab but not in the field, is a series of quiet clicks given by the male while clasping a female.
“Peeps” and “quacks” fill the air these days. How is it that these frog calls travel so far? It’s all thanks to a thin membrane , or sac, that most frogs have. Note the single inflated sac of the spring peeper, and the paired sacs on either side of the wood frog’s head. These vocal sacs act as resonating chambers, causing the male frog’s mating call to be amplified and carried far (some species of frogs can be heard over half a mile away). Most frogs have one of three basic types of vocal sacs: a single throat sac (the most common), paired throat sacs (partially separated by connective tissue) and paired lateral sacs (completely separate chambers on either side of the head). Vocal sacs are outpocketings of the floor of the frog’s mouth. When calling, a frog closes its mouth and nostrils, and expels air from its lungs through the larynx and into the vocal sacs. The vibrations of the larynx emit a sound which resonates within the vocal sacs. The frog continues calling as muscles within its body wall force the air back and forth between the lungs and vocal sac. The thickness of the vocal sac wall in frogs varies. Typically, small frogs that call in the air (spring peeper) have thin vocal sac walls, whereas those that call in the water, particularly large species (green and bull frogs) often have thick-walled vocal sacs that appear swollen, not inflated like a balloon, when filled with air.
The most prominent courtship behavior of male wild turkeys (toms) consists of two displays: gobbling and strutting. Both begin in late February in northern New England, before the females (hens) are receptive, but by late March the males begin to reap the fruits of their labor. The gobbling of the males attracts females or competing males over considerable distances. The tom turkey begins to “strut” only after a hen appears. While strutting, he fans his tail, lowers his wings with the primaries dragging on the ground/snow, elevates the feathers on his back and throws his head backward as he appears to glide around a female. If she is receptive, she assumes a “sexual crouch” on the ground, signaling to the male that he may mount her. (Thanks to Chiho Kaneko for this photograph.)
It’s hard to believe that flies are not only active but mating now, given the snow and low temperatures that Vermont is still experiencing, but these two flies were perched atop coyote scat doing just that. They are in the Heleomyzidae family, whose members are often found in dark or cold places, and are most likely to be encountered in the spring or late fall. There are species associated with caves, mammal burrows, carrion and birds’ nests, in addition to scat.
For the past two to three months, coyote courtship has been taking place. Both males and females have been marking more frequently, and male coyotes have been traveling further than usual in search of a mate. A female has marked the top of the stump in the photograph – you can see the foot prints she made as she squatted to urinate. The blood-tinged urine indicates that she is in estrus, or heat. With luck, you might hear the duet of a male and female coyote that is sometimes sung just prior to copulation.
Flower Longhorn Beetles spend their larval life boring into decaying as well as live trees, depending on the species. As adults they leave their wooden tunnels to find food (nectar and pollen), new trees to tunnel in, and to mate. I recently found several pairs of Flower Longhorn Beetles mating on Queen Anne’s Lace, and all of the males had a transparent hose-like appendage coming from the tip of their abdomen which they inserted into the females as they bred. There is actually a name for this appendage – an aedeagus – and through it sperm capsules are delivered to the female. After breeding, the males retract their aedeagi, so they are not visible. Other insects possess aedeagi in different shapes and sizes, but those of longhorn beetles are considered to be among the most impressive.
Eastern chipmunks typically have two litters a year, each consisting of 1 to 8 young (4 to 5 is usual). They give birth mid-April to mid-May and mid-July to mid-August. The chipmunk in the accompanying photograph has a mouth full of dead leaves which it is carrying back to its underground tunnel where it makes a bulky, leaf nest for its young. When they are born, the young chipmunks are roughly 2 ½ inches long and weigh .11 oz. In about a month start looking for tiny chipmunks – the young are weaned and start venturing out of their tunnels in mid-June.
Roughly a month ago woodchucks were at the peak of their mating season. New England’s largest member of the Squirrel family is about to give birth to two to six young chucks. In preparation for this event, dead grasses are gathered and carried by mouth to the underground nest chamber, which is about 15 inches in diameter. Woodchucks are tidy rodents — the female covers her young’s waste with new bedding placed directly over the old, and when the nest becomes too bulky or unsanitary, the matted material is removed and fresh bedding is added.
Although Spring Peepers emerged from hibernation about two months ago, on warm nights the males are still advertising for mates and will continue to do so into June. Let your ears guide you to the peepers as they call repeatedly, often while perched on low vegetation near water. Armed with a flashlight, look for the movement of their vocal sacs as they inflate and deflate as the peepers sing.
A sure sign of spring is the emergence of woodchucks, the largest members of the Squirrel family in New England, after a long winter’s sleep. Their arousal is easily noted, for when the males wake up, they do some excavating of their tunnel, scattering dirt all around it which is easily spotted on the snow (if there is still any snow left). Equally obvious is the muddy trail they leave when in search of a female. Mating takes place in March and April, and the resulting litters of 2 to 6 young are born a month later.