Winter may be here

edging into a colder season

The days grow shorter and darker, until we turn a corner at the winter solstice and the sun slowly starts to come back. At this time of year, my little excursions tend to be short too. Even so, some things of interest always appear.

Around Thanksgiving time, the West Glacier Trail offered a spectacular collection of hair-frost displays. A cold snap froze many rain-soaked sticks, forcing out thin strands of ice. Some displays featured long stretches of two-inch long curved strands; other displays had multiple sets of shorter strands, each one curling in a different direction, like an enviably wavy hairdo.

Dippers were sometimes foraging and singing in Steep Creek. Two otters, possibly a female with a juvenile, were fossicking about in a nearby pond, observable from the viewing platform. Eventually they went over a small ridge toward the pavilion—and as I went up the ramp in the same direction, I could look down into another pond, where I saw the otters again. The bigger one caught a nice coho and both otters went up the bank to feast. Later, I learned that this was a fish that had been radio-tagged by the Forest Service in the Holding Pond—a fish that apparently backed out and went farther up-river to try Steep Creek instead. The remains of this fish were found by a Forest Service fish biologist.

At the lower end of Steep Creek, a beaver dam slows the main stream just before it reaches the lake and creates a good pond for the beavers’ lodge. Unfortunately, in late November and early December, some very unhelpful person(s) were destroying part of this dam, which thus drastically lowered the water level in the pond. This vandalism served no useful purpose whatsoever. The pond protects the entrances of the beaver lodge; this is the lodge featured in the educational ‘beaver cam’ in the visitor center, allowing visitors to see beavers at home. The pond is also habitat for over-wintering juvenile salmon, as well as feeding sites for dippers and ducks. There were no more coho coming in, and in any case, they commonly enter this pond over a small dam off to the side. Fortunately, a spell of warm weather melted the ice and allowed the beavers to repair the breach in the dam to some degree—there were several new beaver trails going up the banks, for collecting more repair material.

I like to walk along the lake shores when the water level comes down. It’s often a good place to look for animal tracks and sometimes an unusual bird. In late November, I found a nice group of swans in the Old River Channel—three adults and a juvenile—in a spot that seems to be popular with swans on migration.

Then, at the very end of November, there was some snow at Eaglecrest, so it was fun to see what animals had been out and about. Two little explorations with friends noted the usual perpetrators– hare, porcupine, weasel, red squirrel, shrew, a possible coyote, and numerous tracks of deer of all sizes. By the end of the first week of December, there was a lovely thick blanket of snow, traveled by the same array of critters and, by us, on snowshoes. In addition, a small bird, probably a junco, had hopped over a still-open rivulet and spent a lot of time jumping up to reach some seed heads that poked up out of the snow.

In early December, the snow in one of the lower meadows on Douglas was too crusty for the tracks of small things. But again there were lot of deer tracks. A tiny shore pine, no more than three feet tall but possibly quite old, did not seem to be doing very well. It had only eleven tufts of needles on the few living branches. But it bore dozens of old cones—perhaps this was its last attempt to reproduce.

Over on the Outer Point Trail on north Douglas, a friend and I remarked with great pleasure that the recently revised and improved trail passes just below the long beaver dam, leaving the dam undisturbed. Major kudos to CBJ and Trail Mix for using ecological sense!

In the first muskeg after that beaver dam, I noticed something that I should have seen on one of the many times I’ve passed that way: Most of the small pines (less than about three feet tall) were thriving, but virtually all of the mid-size ones (six to ten feet tall or so) were dead. This pattern is not repeated in other muskegs that I have visited recently. So the question is What kind of event(s) might have wiped out a whole size-class of shore pines in this place?

On our way down to the beach, we spotted a few varied thrushes and a red-breasted sapsucker that should have been on its way south by now. We startled a small porcupine, who scuttled off a few feet and waited for us to pass. At the uppermost edge of the beach, a sprawling little herbaceous plant had green leaves and out-of-season buds. Two alders had crossed their branches very closely, rubbing hard against each other until each one had flattened scars where the rubbing occurred. We joked that now they are just ‘rubbing along together’ more or less comfortably.

A stroll with another friend in the Dredge Lake area was not very eventful until we were almost finished. On the trail ahead of us, we spotted two birds. It was so dark that almost no color could be discerned, so it took us a minute to decide what they were. Juncos? No, too big and they were walking not hopping. Blackbirds? No, tail is too short and bill is too stout. Then one of them hopped up into a nearby shrub and a white wing bar could be imagined. But what really gave them away was their characteristic behavior: they were snatching the fruits of high-bush cranberry, stripping and dropping bits of pulp, and gulping down the seed. Bingo! Pine grosbeaks doing their namesake behavior: their scientific name is Pinicola enucleator, meaning pine dweller that extracts ‘nuts’ or seeds.


Clouds for defense

useful obfuscations from the animal world

Animals defend themselves from attack in many ways; a few do this by emitting clouds of stuff that is repellant or obscuring (or both). For instance, humans may carry pepper spray to deter a (rare) bear attack (or, especially in a city, another human). The cloud of noxious spray creates strong burning sensations in eyes, nose, and mouth, and makes eyes flood with tears.

Other kinds of animals make and carry their own noxious spray. Skunks are a good example. North American spotted skunks are currently classified in four species. Their predators include the wild cats, dogs and coyotes, badgers, owls and humans. When feeling threatened and unable to run away, they first stomp their feet; the next step in defiance is their famous handstand – standing on the forelegs, with tail elevated, and back toward the potential attacker, they show off the black and white warning coloration. If the threat continues, the skunk may squirt out its spray from two glands near the anus. It can do this from the handstand but also may drop down to all fours, curl around so that both head and rear end are pointed at the attacker. The oily spray contains sulfur-based organic compounds (thiols or mercaptans) that stink and sting. Each squirt may be fairly accurate at short range but then the droplet s spread around in air currents and can be effective in a wider area.

The striped skunk is native across North America. Its defensive spray is similar to that of spotted skunks, but apparently this species does not do handstands before spraying. After foot-stomping, it just turns around and lets fly in the direction of the threat.

Bombardier beetles of many species occur around the world (except Antarctica). They are famous shooters of noxious spray; some species can even swivel the openings of the jets toward the potential attacker. The chemistry of this spray is remarkably complex. Two glands in the beetle’s abdomen contain hydroquinones and hydrogen peroxide; the glands open into a chamber where the two compounds interact (making benzoquinones). That chemical reaction heats the mixture to almost the boiling point of water and produces a vapor that, under pressure, powers the vigorous ejection of noxious liquid. The spray can kill an insect, such as an attacking ant, and irritates the eyes and respiratory system of vertebrates.

Octopuses, cuttlefish, and squid store ‘ink’ in a sac that opens into the rectum, where it is, in some cases, mixed with mucus. When alarmed, these critters can emit a dense cloud of ink that is carried on a jet of water; the ink hides them from predators and potentially allows them to scoot away to safety. The ink has many components, apparently, including melanin, free amino acids, and metals. In some cases, ejected ink clouds contain extra mucus, and the combined substance takes the form of another octopus or squid, deluding the attacking predator. The ink may also be more than a smoke-screen; it may contain irritating chemicals too.

Large marine shell-less snails called sea hares also emit clouds of ink. The color of this ink depends on the kind of algae the sea hare has been eating: it can be red, purple or white. The ink acts as a smoke-screen against predatory fish, crabs, and spiny lobsters. It also contains toxins that deter feeding behavior of the predator–not only is it apparently unpalatable, it can block and thus de-activate the would-be predator’s sensory system.

Not long ago, a tiny shark captured in the Gulf of Mexico turned out to be a new species, known by just this single specimen. It is related to a similar species that is also known from one specimen, taken from the deep sea off the coast of Chile. These are called pocket sharks, for the unusual pockets behind the pectoral fins. The pockets are glands that produce a bioluminescent fluid. There is also another small shark, in the south Atlantic, called the taillight shark; it produces clouds of bioluminescent fluid from a gland on its abdomen. Apparently the functions of these clouds of glowing fluid are not known—the clouds of light might somehow be used in capturing prey or in escaping from predators.

Humans use clouds as defense too: verbal clouds! When a speaker is challenged by a listener, it is not uncommon for the speaker to emit a spate of words that are only marginally relevant to the challenging question, the words circling round and round a concrete answer. The verbal cloud often dulls the senses and distracts (and frustrates) a listener, hiding an uncomfortable truth or maybe hiding the ignorance of the speaker. I’m sure we can all think of situations in which we have endured these obfuscations!

Hunting partnerships, part 2

humans hunting with animals

Humans have formed hunting partnerships with a variety of animals in addition to honey guides, which were noted in last week’s essay. For example, a traditional method of fishing for ‘opelu in Hawai’i involved rhythmical banging on the side of the canoe to attract the attention of great barracudas (the kaku or ‘opelu mama). As a barracuda approached a school of ‘opelu, the smaller prey fish would ball up for mutual protection in a dense school. This made it easier for the fishermen to net them. Presumably the predatory barracuda caught some too. And in southern Brazil, certain pods of bottlenose dolphins herd mullet toward fishermen waiting in the shallows. With tail slaps or quick dives, they signal to the fishermen, when it is time for the men to throw their nets.

Some partnerships are not such free associations: Once common in China and Japan, trained cormorants were used to catch fish. A ligature on the bird’s neck kept it from swallowing big fish, but it could still swallow small ones. And for centuries, falconers have trained raptors to capture various prey animals, generally sharing the prey (or a substitute food) with the birds.

Perhaps the most widespread and well-known hunting partnership involves humans and dogs. For many thousands of years, we have bred these domesticated canines for various roles in hunting prey—there are retrievers, chasers, trackers, attackers, and so on. A very specialized kind of hunting does not involve killing prey but rather finding things. The powerful olfactory senses of dogs are put to work detecting drugs, contraband imports, and some diseases. Some dogs are even trained to locate invasive plants, such as purple loosestrife. Search dogs are trained to find lost persons, living or dead, on land and even in water. Some years ago, a dear canine friend could always find me, hidden in the woods, no matter how my trail circled or backtracked, or find my ‘stuff’ if I happened to drop it along the trail.

In Juneau, the excellent noses of dogs are put to work in bat research. First, a little background on previous work on bats, to set the stage for the participation of dogs. An ADFG research program has been radio-tagging and monitoring bats in the Juneau area for several years, focusing primarily on the common little brown bat (Myotis lucifugus). Radio-tagged bats have been tracked to hibernacula in two places (so far): rocky crevices on steep forested slopes on Douglas Island and on Admiralty Island. The bats begin to hibernate in mid-September or so.

Before settling in for the winter, the bats seem to signal to each other about a prospective location by circling with sharp turns near a particular crevice, reaching a peak in the dark hours of the night in late July, August, and early September. This flight behavior is known as ‘swarming’. It has been well- documented in eastern and midwestern North America, where large numbers of bats circle or ‘swarm’ around cave and mine entrances. In contrast, in our area, each crevice seems to be used by only a few bats, although the circling flight pattern is still called ‘swarming’.

Game cameras are set up near rocky crevices to which the radio-tagged bats have been tracked. The cameras can record the circling flights and sometimes also one or two bats (as well as mice and shrews) crawling into a crevice and staying for a while. Mating presumably occurs at this time, in these crevices, in late summer and early fall, but fertilization is delayed until early spring, when females emerge from hibernation. They emerge before the males do, and go to maternity roosts in warm places such as attics. After a gestation period of about three months, the young are born and can usually be ready to fly in about three weeks.

To expand our understanding of the habitats used by hibernating bats, ADFG bat biologists and volunteer ‘citizen scientists’ do road surveys, listening for bat vocalizations with special bat detectors. These surveys are primarily focused on finding areas of concentrated bat activity at the seasons of entry to (and emergence from) hibernation. Then foot surveys in those areas look for the right kind of habitat; bat detectors are used to see if bats are really at that area and identify the species of bat. If all that points to the presence of bats, trained bat-scent-detecting dogs are brought in, particularly during the time of beginning hibernation (the so-called swarming period), to sniff out the exact crevice housing the bats. When a search dog signals that it has detected the scent of bats at a particular crevice, researchers may look for the distinctive feces of bats in the crevice. To determine if the selected crevice is just a day roost or an actual hibernating site, more equipment is set up in the early fall to detect swarming behavior outside the crevice and eventually determine that the bats are really hibernating there.

So far, the scent-detecting dog searches show great promise for locating hibernacula (although not in the rain), and the method should be tested elsewhere, in other habitats and climates. In the meantime, the method will be used here to locate more hibernacula and develop a clear picture of the habitat needs of the bats. That’s critical information for land managers—and a great application of an ancient hunting partnership between humans and canines.

Thanks to Tory Rhoads, ADFG, for a good conversation about local bat research and the use of sniffer-dogs to locate hibernacula.

Hunting partnerships

animals that hunt together

We are accustomed to hearing about wolves or killer whales that hunt in cooperative packs. And sometimes, conspecific animals can work in pairs. In the marshes where I worked long ago, I could sometimes watch two coyotes team-hunting ducks—one to keep the duck’s attention while the other crept up behind. And here, we can see eagles working as a team: one swoops down on a duck, which promptly dives, and the second eagle pounces as the duck resurfaces. Ravens also sometimes work in teams, one bird distracting an eagle that has a fish and the other one dashing in to snatch the fish.

Less well known are hunting partnerships between animals of different species. In a true partnership, both participants obtain some benefit, and that is sometimes difficult to demonstrate. Here are some proposed examples, often with insufficient documentation to make a solid case for a true partnership.

Wolves and ravens. Ravens are so often associated with wolves that they are sometimes called ‘wolf-birds’. When wolves kill a large animal, such as a deer, moose, or elk, they tear open the carcass, which allows ravens to scavenge lots of sizable tasty bits; without the opened carcass, the ravens are limited to snatching eyeballs and maybe part of the tongue. Wolf researchers have observed that travelling wolf packs are commonly followed by ravens, which clearly benefit from the more profitable scavenging.

But do wolves get anything from the attendant ravens? Some observers have claimed that ravens lead wolves to carcasses, but these claims may be more story than fact. One long-time wolf researcher noticed that when ravens accompany wolf packs, they would sometimes fly ahead, in the direction of travel, and wait for the wolves to catch up—which could appear to be leading the wolves. If a gang of ravens yells and calls when they discover a carcass, wolves could notice and might come; then both ravens and wolves could feast. The ever-observant ravens might alert feeding wolves to possible interlopers and disturbances, but how often this would be useful is not known. Maybe the potential value to wolves varies with conditions and location, and we should keep an open mind on this question, awaiting more research.

In an interesting twist on wolf-raven interactions, there are strong indications that the professional-level scavenging by ravens may be important in determining the size of wolf packs. A larger pack is better at fending off marauding ravens than a small pack, so more meat is available to the wolves. Of course, that’s also more wolfish mouths among which to divide the meat, but at least in some cases, the advantage of larger wolf numbers outweighs the disadvantage, so wolf packs are commonly bigger than two or three hunters.

Coyotes and badgers. A study in Wyoming found these two predators interacting in ways that suggested collaboration while hunting ground squirrels. Badgers hunt by digging into ground squirrel burrows, blocking off tunnels, and trapping prey in dead-ends, but sometimes the squirrels escape by emerging above ground. Coyotes there chase and pounce, although sometimes a squirrel dives into another tunnel system, there to be pursued by badger. The coyotes clearly benefited: they caught more squirrels when they were interacting with badgers. Because the badgers catch their prey underground, it is harder to tell what their hunting success might be, but they spent more time underground when they were interacting with coyotes and they might have been feasting. More data needed!

The apparently collaborative hunting typically involved single coyotes, not pairs or trios. They seemed to hear the badgers’ burrowing activity and solicit interaction by scrambling in a particular area or showing play behavior when the badger appeared. However, female badgers with young did not participate, rebuffing soliciting coyotes. The cooperative interaction occurred in sagebrush habitat where coyotes had limited mobility and where the sagebrush roots made badger digging somewhat difficult. Collaborative behavior was not observed where both critters had easy hunting or where coyotes are harassed and shot by humans.

Groupers and moray eels. Groupers are sizable predatory fish that live on coral reefs around the world; moray eels are predators that usually forage at night. Groupers sometimes hunt with moray eels, particularly if they are hungry (well-fed ones don’t do it), and an eel can be coaxed to forage during the daytime. A hungry grouper seeks out a moray eel that’s resting in a hole in the reef. It faces the eel, close-up, shaking its head and flicking its dorsal fin. If the eel is interested, out it comes. If the eel is reluctant to emerge, the grouper signals more vigorously. If the grouper manages to recruit the eel, the eel slithers in and out of crevices in the reef and the grouper lurks about nearby. When the eel flushes a small fish out into the open, the grouper may grab it—or chase it back into a hole where the eel can get it. If the prey fish gets away and hides, and if the grouper knows where it is, the grouper gives a more vigorous head-shake to the waiting eel and they may try again. Both animals feed well when they use this method.

The peacock grouper was introduced to Hawai’i from the Indo-Pacific region. Morays in Hawai’I respond to the foraging invitations of these foreigners, which apparently know how to behave as well as the native groupers. So a new association was established.

Groupers have also been seen signaling to octopuses, which may join in a hunt. They can insert their long tentacles into crevices and scare out the hiding fish. Grouper or octopus may catch the fish.

Honey guides and honey badgers. This is the classic, often-cited example of interspecific foraging partnerships. Honey guides are birds of Africa and Asia that have the unusual habit of feeding on beeswax and larvae, but they cannot open a tree cavity that houses bees. Honey badgers are tough weasel-like omnivores that love honey (and probably bee larvae), sometimes raiding domestic bee hives. Certain species of honey guides are said to lead badgers to bee colonies; the badgers rip them open to expose the comb, with its honey and larvae, and both animals feast. However, there is serious doubt about this collaboration; some scientists report that it is basically a myth, with no factual evidence. However, the honey guides do work with humans that will open the cavity, making the goodies inside available to both bird and human. Honey-hunters of some African tribes use special calls to bring honey guides into action. Obviously, these two interspecific interactions are not mutually exclusive, but the badger connection may need to be verified.

Hunting humans interact with many different animals in collaborative ways; of which, more next time.