Hands down, Bald Eagles (like the 2nd year immature bird pictured) prefer fish over other prey — roughly 56% of the diet of nesting Bald Eagles consists of fish such as salmon, herring, shad, and catfish. However, eagles are opportunistic foragers and over 400 species of prey have been recorded, half of which are waterbirds. Reptiles, amphibians, invertebrates such as crabs and crayfish, and small mammals such as squirrels, rabbits, muskrats, young beavers, fawns and raccoons are also subject to Bald Eagle predation.
During their first year, until they learn to be proficient hunters, Bald Eagles frequently feed on carrion. Even as adults, eagles regularly consume roadkills and deer that have died as a result of being stranded on ice. Whatever food is available and requires the least amount of energy to capture is usually high on their list.
Although not considered a primary source of food, domestic pets are subject to occasional predation by eagles. A discovery made by Fish & Wildlife personnel engaged in banding Bald Eagle nestlings may be of interest to cat owners who allow their pets to roam free in the great outdoors. Upon reaching one nest, they found, among the detritus, over 20 cat collars.
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Every fall, roughly three months after they’re laid, snapping turtle eggs hatch. Like many other turtle species, the hatchlings’ gender is determined by the temperature at which the eggs were incubated during the summer. Eggs at the top of the nest are often significantly warmer than those at the bottom, resulting in all females from the top eggs, and all males from the bottom eggs. In some locations, the hatchlings emerge from the nest in hours or days, and in others, primarily in locations warmer than northern New England, they remain in the nest through the winter.
When they emerge above ground, the hatchlings, without any adult guidance, make their way to the nearest body of water, which can be up to a quarter of a mile away, and once there, seek shallow water. Eggs and snapping turtle hatchlings are extremely vulnerable to predation. Predators include, among others, larger turtles, great blue herons, crows, raccoons, skunks, foxes, bullfrogs, water snakes, and large predatory fish, such as largemouth bass. Older and larger snapping turtles have a much easier time fending for themselves. (Photo: newborn snapper)
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Coyote tracks from three different directions led to an area where a deer’s well-cleaned skull was the only remnant of a communal meal. It had been dug up from a spot nearby where it had been cached, and carried to a more protected area to work on. Coyotes are omnivores, but about 90% of their diet consists of mammals. Coyote scat I’ve examined has included, among other things, the hair of Muskrat, Snowshoe Hare, White-tailed Deer and small rodents as well as feathers, grass and apples.
Coyotes are commonly blamed whenever there is a decline in the White-tailed Deer population. Studies involving the removal of deer populations in a given area have not found any evidence that Coyote removal caused an increase in the deer population, nor did it affect the overall deer population growth. The fact that Coyotes are not causing deer populations to decline can also be seen in the devastating effect White-tailed Deer are having on forest ecosystems throughout the eastern United States as the Coyote population increases.
That’s not to say Coyotes don’t hunt deer – they do, primarily in the spring (fawns) and in the winter, especially when there is enough snow and/or crust to slow deer down but not Coyotes. However, much of their venison consumption is a result of their scavenging deer carcasses, which they do any time of year. Examine Coyote scat and the chances are great you will find deer hair in it; chances are also great that it came from a carcass, not a living deer.
At this time of year when most flowers have gone by, Canada Goldenrod (Solidago canadensis) is a primary source of pollen and nectar for bees, beetles, butterflies, flies and many other insects. Consequently, goldenrod flowers are a popular place for insect-eating predators to linger.
Recently I spied an Ambush Bug that had captured a fly and had its proboscis inserted into it, contentedly sucking away the fly’s innards while I photographed it. Unbeknownst to me or the Ambush Bug, another predator, a Bald-faced Hornet, had spied the bug with its prey. Although adult hornets consume liquids, usually sugars like the juice of fruits or nectar, their larvae are raised on a diet of insects, so adults are constantly looking for prey. Suddenly, out of nowhere, the hornet flew in, tussled with the Ambush Bug and flew off with the fly in its mandibles, landing on a nearby branch with the object of its thievery.
Rarely have I had the good fortune to come upon a predator dining on its prey, but in this case, luck was with me. Seconds after I spotted a Red-tailed Hawk on the ground working on something it noticed me and flew away, perching within sight so as to keep an eye on its recent kill. This sighting eliminated some of the mystery of the story written in the snow. Wing prints would have revealed that the predator was airborne, and the wingspread might have narrowed the list of potential hawks/owls that it could have been, but determining the species would have been challenging without a sighting.
Although smaller rodents (voles, mice, etc.) make up a greater percentage of a Red-tail’s diet than larger ones, Gray Squirrels (whose remains are visible and were still warm) are consumed. The large numbers of Gray Squirrels on roadsides last fall reflected a booming population which most likely has provided ample food for many predators this winter, including this hawk. Interestingly, fur from the tail had been removed prior to the bird’s directing its attention to the internal organs of the squirrel. A quick retreat by this curious naturalist hopefully allowed the Red-tail to return to its meal.
Over the past century beaver trapping has declined and beavers have returned to many of their former habitats. Wolves also have come back in a few areas (not the Northeast yet) — but most places where beavers now live remain free of wolves. As a result, the beaver population has continued to increase, limited only by a few predators, primarily humans and Eastern Coyotes.
Coyotes are major beaver predators and have established themselves throughout the Northeast partly because of the abundance of prey and partly because of the absence of wolves, who keep coyotes out of their habitat. During most of the year, coyotes can take advantage of beavers that leave their pond to feed on land. When they are in their lodges, however, beavers are fairly safe from coyote predation, especially if their lodge is surrounded by water. Come winter, when ponds freeze and beavers remain in their lodges, coyotes can easily approach an inhabited lodge by walking over the ice. Thanks to the lodge’s two to three-foot-thick walls of frozen mud and sticks, the beavers within are safe. (Photo: signs showing a coyote’s attempt to access a beaver lodge)
Spiders are ectotherms – warmed and cooled by their environment. In the fall, those outdoor species that remain alive through the winter begin preparing themselves by producing antifreeze proteins that allow their tissues to experience below-freezing temperatures. When a small particle of ice first starts to form, the antifreeze proteins bind to it and prevent the water around it from freezing, thus preventing the growth of an ice crystal. Some species survive in temperatures as low as -5 degrees Celsius.
The pictured hammock spider, still active in late October, is nourishing itself by drinking the dissolved innards of a fall-flying March fly, whose name comes from the predominantly springtime flight period of most March Flies (of the 32 species in the genus Bibio in North America, only three fly in fall).
A common belief is that once cold weather appears, outdoor spiders seek shelter inside houses. In fact, only about 5% of the spiders you find in your house lived outside before coming into your house, according to Seattle’s Burk Museum. The reason people tend to notice them more inside may be because sexually mature male spiders become more active in the fall, wandering far and wide in search of mates.
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There is a reason why ducklings remain with their mother for their first month or two of life. It takes 50-70 days before most ducklings can fly, and survival during this period is highly variable, ranging from less than 10 percent to as high as 70 percent. They are at their most vulnerable during this stage. The most common causes of duckling mortality include predation, adverse weather conditions, starvation, disease, and parasites. The mother offers her young a degree of protection from some of these factors while they are under her care.
Predation is arguably the greatest threat to young waterfowl. Ducklings are sought after by nearly every type of predator, including other birds (eagles, hawks, owls, herons, crows), fish (largemouth bass and northern pike), amphibians (bullfrogs), reptiles (snakes and snapping turtles), and mammals (foxes, raccoons, and mink). Their odds for survival increase dramatically when the ducklings obtain the ability to fly. (Photo: female Wood Duck and ducklings)
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With snow on the ground, the season of stories in the snow has begun. Many of the animals that remain active in New England during the winter are nocturnal so we rarely get a glimpse of them. But, more than at any other time of year, we are privilege to their activities due to the tracks and traces they leave in and on the snow during the night.
Much information can be gathered from these signs. Often at a kill site, the identity of the predator as well as the prey can be determined by shape, form or measurement. One can see from this photograph that a bird of prey (measurements indicate a barred owl) swooped down on a small rodent (judging from tracks, probably a meadow vole) and was successful in capturing it.
Even though a kill scene such as this, or any other wildlife activity recorded in the snow, may reveal the probable identity of the characters in the story, there are always more questions than answers, which is what gets us out in this frigid weather, day after day. The main question I’m left with after viewing this scene is why do voles and mice risk their lives by travelling on the surface of the snow at times, when they just as well could have covered the same ground in the maze of tunnels they’ve created deep in the subnivean layer between the ground and the snow (where they would be out of sight of hungry predators)? (Thanks to Rob Foote for photo.)
There are over 1,000 North American species of solitary hunting wasps. All of them prey on arthropods, which the female stings and paralyzes (but doesn’t kill so that they don’t begin to decompose immediately). Most solitary wasps specialize on a single type of prey, and many build highly characteristic burrow nests. Once the prey is stung, the wasp carries it back to her nest where she then lays a single egg and closes up the nest. The developing wasp larva feeds on the paralyzed prey, pupates and emerges as an adult wasp.
One group of solitary hunting wasps is referred to as thread-waisted wasps (family Sphecidae), due to their long, stalk-like waists. While most close up their nests (by kicking sand over the entrance) after stocking it with prey and laying an egg, some species close their nest with a pebble and return, remove the pebble, and periodically restock the nest with fresh caterpillars for the growing larva. (Photo by Mardie Holland: thread-waisted sphecid wasp with caterpillar prey)
Striped Skunks do have predators other than Great Horned Owls (bobcats, foxes and coyotes-fishers have been known to prey on skunks, but very infrequently), but these predators have to be pretty desperate before they will prey on a skunk. Automobiles and disease kill more skunks than all of their predators put together, but Great Horned Owls have the distinction of being the primary predator of Striped Skunks.
Being a nocturnal hunter, a Great Horned Owl necessarily consumes prey which are nocturnal. Striped Skunks are active at night and are consumed by Great Horned Owls with regularity, even though a skunk can weigh up to three times as much as a Great Horned Owl (average GHO weighs a little over 3 pounds) and has a potent way of defending itself.
For many years scientists assumed that birds had a poor sense of smell because the area of a bird’s brain involved in smell is relatively small compared with the area found in mammals. However, recent research reveals that birds have a high number of active genes that are associated with smell, and many species may have an excellent sense of smell. It’s fairly safe to assume, however, from its consumption of skunks, that the Great Horned Owl’s sense of smell is not very well developed. In addition, if a skunk sprays, much of the odor is absorbed by the Great Horned Owl’s leg feathers, which extend down to its talons.
A favorite memory of mine is walking through a field at dusk and suddenly noticing a strong skunk-like smell coming from above, not below, me. A Great Horned Owl silently flew overhead, with only the tell-tale smell of a recently-captured skunk announcing its presence.
Short, powerful, rounded wings and a relatively long tail enable Sharp-shinned Hawks to maneuver in dense cover in pursuit of small birds, which compose 90% of their diet. Small mammals and insects are consumed, but not nearly as frequently as birds. The size of the birds eaten range from hummingbirds to Ruffed Grouse. Long legs and toes (especially middle toes) enable individuals to reach into vegetation and large eyes enhance its ability to catch fast-moving prey.
Sharp-shinned Hawks are familiar sights to those of us with bird feeders – this species is responsible for 35% of 1,138 predation incidents reported at feeders in continent-wide survey. In this photograph, a Blue Jay is successfully warding off an attack by a juvenile Sharp-shinned Hawk. (Photo by Jeannie Killam.)
The robber fly family, Asilidae, is one of the largest families of flies. All robber flies are predaceous and are recognized by their long bodies, forward-facing beaks and a tuft of hairs above the beak. You find them on the ground or on leaf tips and other sunny spots where they survey the area for flying insects. Once a robber fly has spotted a suitably-sized prey, it darts out and impales it with its stout beak. It then inserts its needlelike “tongue” into the prey’s neck, eye or other weak spot, immobilizing the insect and liquefying its innards with an injection of saliva that contains nerve poisons and enzymes that break down proteins. Finally, it drinks its meal. Pictured is a species of robber fly in the genus Diogmites, whose members are known for dangling by a foreleg while dining.
Inevitably, as newly-emerged drying dragonflies and damselflies hang over the surface of the water on emergent vegetation, breezes blow and some of them lose their grip, falling into the water below. At this stage, their bodies are soft and they are not capable of flight, which leaves them very vulnerable to aquatic predators such as Eastern Newts. While amphibian eggs, aquatic insects, crustaceans, worms and small molluscs make up most of their diet, Eastern Newts are quick to make a meal of most invertebrates that end up in the water.
Miterwort (Mitella diphylla), also called Bishop’s Cap, is named for the resemblance of its two-peaked fruits to the hats (known as miters) worn by bishops of the Roman Catholic Church. This spring wildflower produces miniature five-pointed snowflake flowers that beg to be examined with a hand lens.
Gnats, small bees and syrphid flies all seek out Miterwort for its nectar. Because its nectaries are located just below the stamens, the flower is pollinated by the mouthparts of the pollinators which brush against the stamens when collecting nectar and the inadvertently-gathered pollen is transported to other Miterworts. Predators such as the Goldenrod Crab Spider (pictured) know that potential meals are plentiful near these delicate flowers.
Fishers are rarely seen, as they tend to travel in wooded areas and not expose themselves in open areas. However, this fisher was so intent on getting a meal that he threw caution to the wind. Fishers are generalist, opportunistic hunters and scavengers, consuming a wide variety of animals and plants. Basically, if it can catch it, a fisher will eat it – amphibians, reptiles, invertebrates, birds and bird eggs, and mammals (snowshoe hares are at the top of the list, but rabbits, squirrels, small rodents, shrews, and porcupines are common prey).
Between its keen sense of smell, and its acrobatic abilities (due to the flexibility of its hind feet, which can be turned 180°), a fisher is able to take advantage of prey and access food wherever it may be – in the tallest tree, or, in this case, a wood duck nest box.
Noted New Hampshire naturalist/tracker/videographer, Alfred Balch, succeeded in documenting the pictured fisher swimming out to an active wood duck nest box, climbing inside and exiting with a wood duck egg gently held in its mouth. It was observed doing this more than once. Considering that wood duck clutches consist of anywhere from 6 to 16 eggs, this fisher’s stomach was probably full by the end of the day. The wood duck is the only duck in North America that regularly produces two broods in one season, so hopefully the second clutch will escape the fate of the first. (Photos by Alfred Balch)
An owl’s range of audible sounds is not unlike that of humans, but an owl’s hearing is much more acute at certain frequencies, enabling it to hear even the slightest movement of their prey under two feet of snow. When a noise is heard, the owl is able to tell its direction because of the minute time difference in which the sound is perceived in the left and right ear. If the sound is to the left of the owl, the left ear hears it before the right ear. The owl turns its head so the sound arrives at both ears simultaneously, at which point it knows its prey is right in front of it. Owls can detect a left/right time difference of about 0.00003 seconds.
Once an owl has determined the direction of its next victim, it flies towards it, keeping its head in line with the direction of the last sound the prey made. If the prey moves, the owl makes corrections mid-flight. When about two feet from the prey, the owl brings its feet forward and spread its talons, and just before striking, thrusts its legs out in front of its face and often close its eyes before the kill. (Photo: barred owl wings and feet imprints; inset: barred owl ear opening.)
When there is deep snow on the ground, white-tailed deer are often preferred-eating for eastern coyotes, with snowshoe hares not far behind. While small rodents are also consumed during the winter, they make up a larger proportion of a coyote’s diet during spring, summer and fall. With only a few inches of snow on the ground currently, meadow voles are still very vulnerable to predation, as the tufts of grass where they tend to nest are still visible.
Tracks indicate that a coyote stopped to investigate numerous grass tussocks scattered throughout a nearby field recently. Near several of these clumps of grass were slide marks (see foreground in photo) where the coyote had jumped, landed and slid. The groove made by the coyote’s sliding foot always ends with a foot print. At this particular site, the coyote had pounced, slid and then dug and uprooted a nest, possibly procuring a vole, but leaving no trace of success behind. What it did leave behind was scat (3 o’clock in photo), with which the coyote claimed ownership of the site.
Ruffed grouse typically have a short life span; few live to be three years old. By mid-August about 60 percent of the grouse hatched that year are lost to predators, weather extremes, disease, accidents (such as flying into windows) and hunters. Less than half of the surviving young survive through the winter to have a chance to breed in the spring, and less than half of those that survive long enough to breed make it to a second mating season. The hazards for a ruffed grouse are many, with predation at the top of the list.
Birds of prey, especially the goshawk and great horned owl, take many grouse, but terrestrial hunters such as foxes, coyotes, bobcats and fishers also take advantage of this plentiful food source. Along with hares, porcupines, squirrels, mice and voles, grouse are one of the fisher’s preferred foods. A fisher managed to capture a ruffed grouse in the pictured scene, leaving only tracks and a few tell-tale feathers to tell the story.
Predators and scavengers of all stripes are reaping the benefits of deer hunting season. A close look at the composition and form of the pictured scat reveals much more than the fact that a coyote dined on a white-tailed deer. Note that the scat consists almost entirely of deer hair. When a predator such as a coyote comes upon a carcass, it tends to eat the internal organs first, which produce black, moist, soft scats with next to no bones or hair in them. As it continues to feed, the coyote’s scats contain more and more bones and hair, until eventually that is all they consist of.
There are two conclusions one could make when analyzing this scat. One is that the coyote whose scat this is was finishing up the tail end of a deer carcass. It is also possible that this coyote might not have been at the top of its pack’s hierarchy. The alpha pair usually has first dibs on the internal organs, with lower members of the pack having access to the less choice parts, such as hair and bones.