Determining An Eastern Chipmunk’s Gender
Ordinarily, one can’t tell a male from a female eastern chipmunk as they look identical –but there are two times during the year when it is possible, with luck and good eyesight, to tell one from the other. One is right now, in the early spring, when chipmunks first emerge from their underground burrows. Male chipmunks appear first, followed by females one or two weeks later. The first of two breeding seasons is beginning for chipmunks. Upon emerging, the males’ testicles descend, making the males distinguishable from the females. Their scrotal sac is covered with whitish-gray fur; the darker the fur the more mature the chipmunk is.
During their breeding season, males travel outside of their home ranges, often some distance, to locate females and check on their reproductive condition. The females chase and wrestle with the males to see who can keep up with them. When a female comes into estrus (the end of February/ beginning of March) she chooses her mate. The chosen male flicks his tail vertically and screams prior to copulation (another way to distinguish the sexes). After the first mating season, the testicles ascend until the second breeding season in middle to late summer, when the chance to determine the gender of chipmunks once again presents itself.
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Spotted Salamander Spermatophores
After male spotted salamanders emerge from hibernation and arrive at their ancestral breeding (vernal) pools, they cluster in groups called congresses, await the arrival of females, pair up with one and then the pair performs a courtship dance.
Unlike some species of amphibians, the male spotted salamander does not fertilize the eggs as the female lays them. Rather, she collects his sperm into her body and internal fertilization takes place. When the female is sufficiently stimulated, the male deposits up to 80 spermatophores (pyramid-shaped plugs of mucus with a sperm capsule at the top), often on a submerged branch. The male maximizes the chances of insemination by depositing many scattered spermatophores, covering every spermatophore he encounters, even his own, with a new spermatophore. In so doing, he increases his spermatophore count, while simultaneously eliminating a rival’s spermatorphores. The female then crawls over a spermatophore and positions her vent, or cloaca, so as to allow the lips of her cloaca to detach the sperm capsule.
Within a short period of time the salamanders retreat back to the woods, rarely to be glimpsed until next spring’s breeding season. (Photo: spotted salamander spermatorphores, with sperm capsule missing on far left spermatophore)
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Determined Spotted Salamanders
It’s rare to get a glimpse of a Spotted Salamander – these secretive amphibians spend most of their lives hidden under rocks or logs or in the burrows of other forest animals, emerging only at night to feed and during spring mating. In central Vermont, the annual mass migration of Spotted Salamanders to their ancestral breeding pools began two nights ago, when the rain-soaked earth and rising temperatures signaled that it was time to emerge from hibernation. Unfortunately for the salamanders (and frogs) that answered the calling, temperatures dropped relatively early in the evening, and the rain turned to snow. Undaunted, these stout salamanders continued their trek through the woods, plowing their way through new-fallen snow, all in the name of procreation.
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Moose Wallow
As the moose rutting season comes to a close, signs of their breeding behavior are fewer and not as fresh. The pictured moose wallow, or rutting pit, was most likely created by a bull moose as a means of spreading his pheromones to receptive cows (although cow moose have been known to make them). After scraping the ground, the bull then urinates in the depression and stamps in it to splash the urine on his antlers (“antler perfuming”) and/or lies down in it, soaking the under side of his body, including the dewlap, or bell, that dangles beneath his neck. Every soaked surface serves to advertise his presence to cows in the area. Often the sound that the bull makes splashing the urine attracts cows, who run toward the bull and, by head bobbing and attempting to drink the urine (the sipping sound is attractive to both cows and bulls), encourage him to urinate more. (Thanks to Alfred Balch for photo op.)
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American Toads Calling
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.
Muskrat Division of Labor
Although muskrats are primarily nocturnal, you occasionally see them in the daytime, especially in the spring and fall. They often reside in ponds or marshes, where they live in the pond bank or build their own house out of mud, cattails and other available plant material. Muskrats are herbivores, favoring cattail roots, arrowhead, bur reed, pickerelweed and other aquatic vegetation. The pictured muskrat is not feeding, however — more often than not muskrats eat their food where they find it, especially during the warmer months. It is doing its share of parental care — this is the time of year when the first of several litters of muskrats are born. While the mother nurses her four or so young, the father spends time gathering bedding material for his offspring. The muskrat in this photograph spent a morning cutting and gathering several mouthfuls of grasses growing by the side of the pond. When he couldn’t fit one more blade of grass in his mouth he would scurry down the bank and disappear into a burrow which most likely led to a chamber where his young are being raised. Like their beaver cousins, muskrats tend to keep a tidy house and forage for fresh bedding for their young with some regularity.
Common Grackle Threat Display
Although the common grackle, a member of the blackbird family, is the bane of many corn growers as well as a threat to songbirds trying to raise young (grackles eat other birds’ eggs and nestlings), it is quite a colorful bird, with its pale yellow eyes and iridescent purple plumage. Grackles have already begun nesting and defending their territory, as can be seen from the stance of the bird in this image. This “bill-up display” is a position assumed when a male is being approached on its territory by another male. It moves its head upwards so that its bill is almost vertical, signaling to the approaching grackle that it would be in its best interest to depart.
Pickerel Frogs Calling
If you’ve spent time at a pond recently and heard what sounded like someone snoring, you weren’t hallucinating! Male pickerel frogs have started calling to attract mates, and each species of frog, just like birds, has its own distinctive call. Spring peepers peep, wood frogs clack and pickerel frogs snore. Their snore isn’t long – it only lasts a second or two — but it’s unmistakable. Pickerel frogs call from under water, as well as on top of mounds of vegetation, so if you hear one and then search for it, it’s very possible you may not find it. (My sincere apologies-computer failure prevented me from posting on the previous two days.)
Spring Peepers Mating & Laying Eggs
The mating season for spring peepers lasts two months or more, and judging from the sound that is coming from ponds and woodlands these days and nights, it is in full swing. Once a singing male is successful in attracting a female, he mounts and clasps her while depositing his sperm on her eggs. She lays up to 800 eggs, either singly or in small groups, on plants within the male’s territory. The frogs remain joined (a position known as “amplexus”) for up to four hours. After egg-laying and fertilization is completed, the female peeper returns to the woods; the male remains at the pond and resumes singing.
Great Blue Herons Mating
Numerous displays lead up to the mating of great blue herons – neck stretching, bill clacking, wing preening, circling flights, twig shaking, crest raising, neck fluffing, to name but a few. After this elaborate courtship comes copulation, which is not nearly as showy. Copulation typically takes place on the nest. The male places one foot gently in the center of the female’s back. The female leans forward, bends her ankles and holds her wings slightly away from her sides while the male lowers himself, often flapping his wings. Once the job is done, the male flies off. If you look closely you can perhaps make out that the male is grasping the female’s head/neck while copulation takes place.
Wild Turkeys Mating
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.)
Autumn Meadowhawks Mating
Meadowhawks are the only small red dragonflies seen in New England (most males are red, most females are brown).The latest species of dragonfly flying in the fall in this area is the Autumn Meadowhawk (Sympetrum vicinum), which doesn’t emerge until mid-summer. It seems a bit incongruous to observe these dragonflies not only flying, but mating and laying eggs in late October, but that is exactly when you can expect to see them. Until there have been several hard frosts, these winged masters of the air are able to keep active by basking in the sun and warming their flight muscles. The two pictured Autumn Meadowhawks are copulating in the typical “mating wheel” fashion, with the male grasping the female behind her head while the female places the tip of her abdomen at the spot on his abdomen (the seminal vesicle) where he stores his sperm. The female Autumn Meadowhawk lays her eggs in tandem with the male (his presence prevents other male meadowhawks from replacing his sperm with their own).
Mating Flower Longhorn Beetles
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.
Mystery Photo Solved!
Well done, those of you who guessed Wild Turkey, which was most of you! Charlotte Carlson not only discovered their nest, but managed to photograph the hen and tom turkey in the act of making the eggs!
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