Toads, sticklebacks, and aphids…

A short visit to Gustavus in mid-July yielded a diversity of interesting observations. My friend had a report of toads near a gravel pit, so we went out to see. We found the place teeming with human kids and parents, actively (and loudly) enjoying a swim on a very hot day (over eighty degrees; that’s sweltering in Southeast!). So we dove into the woods instead, wandering here and there, and on our way back to the car, we noticed some very odd tracks in the dusty road: Toes of uneven length, the stride a sweeping motion through the dust. Can’t be a mammal or a bird—aha, it was a toad, walking (with toes dragging) instead of hopping for many yards in the roadway. Very cool—I’d not seen such clear toad tracks before this.

Late that evening, we returned to the pond, when the human crowd had gone home. Now we could see dozens of tiny toadlets hopping about in the brush that fringed the pond. In the shallow water there were tadpoles at various stages of transformation into toadlets: some fat-bodied tadpoles with no hind legs worth mentioning and a stout tail, some almost-transformed toadlets with little tail left and good swimming legs, and others in between.

Seeing all these stages of development prompted me to wonder about how a developing toad changes its diet. Tadpoles are considered to be herbivorous, in general (although some species are carnivores), grazing on small particles in the biofilm of algae, bacteria, and perhaps fungi that grows on the surface of rocks and weeds or filter-feeding on planktonic algae. Toadlets and adult toads forage on insects, capturing them with a long tongue and swallowing them whole. Changing from vegetarian to meat-eating necessitates major changes in the feeding apparatus and digestive tract. The small tadpole mouth disappears, replaced by a wide mouth, a jaw, and a tongue. The stomach gets bigger. The intestine becomes shorter and better supplied with absorptive surfaces. New enzymes are produced. During the principal time of change, the animal actually stops feeding until the changeover is complete. That might explain why just-emerged toadlets often look so thin. Then the newly equipped toadlets have to learn how to forage effectively for bugs. That seems like a big job!

Swimming with the tadpoles were lots of sticklebacks. There were schools of tiny hatchlings and plenty of fat, gravid females with a load of eggs inside. They will seek out a nest made by a male and lay their eggs inside, for him to tend. A male fans a nest with his pectoral fins to improve water and oxygen flow and defends it against potential enemies. Nests are small tunnels built of bits of debris and algae, and they are hard to find. However, Bob Armstrong has a nice video of a male guarding and fanning his nest (search for this at naturebob.com).

The next day we took a walk through the grassy, sedge-y meadows that stretch from the forest to the beach. Near the start of the trail we saw several families of barn swallows, all lined up on a wire or packed into a shady corner, still being tended by busy parents. There were Lincoln’s sparrows at the edges of willow clumps and alder flycatchers singing in the thickets.

One of our goals was finding some sweetgrass (the common species that grows here apparently goes by two scientific names, depending on which book you consult: Hierochloe odorata or Anthoxanthum hirtum). Sweetgrass has been used by native cultures around the northern hemisphere for its aroma and for braiding into basketry. We found it easily, its quite distinctive inflorescence mixed in a community of other species. Of course, we gathered a little and made a couple of simple braids, just for fun; for practical use, the stems should be gathered earlier in the season when they are greener and more pliable.

Canada goldenrod was flowering splendidly, and a number of plants had infestations of aphids. Some of the aphids had wings. We were amused to see that when these wee insects were approached by a finger, they tended to rear up their hindquarters, often in a wave proceeding up the stem, a bit like The Wave performed by sports-fans in an arena. Other kinds of aphids do something similar. For the aphids, this could be some kind of defensive reaction, but against whom?

There was other good stuff to be seen and heard. At the edge of the forest, we looked at two empty chickadee nests, one in an old snag and one in a nest-box. To our surprise, both nests were simple thick mats of moss, without the expected cup in which eggs and chicks would nestle. We were entertained by juvenile nuthatches calling continuously from the conifers in hopes of parental attention. We visited the site where a winter-killed moose carcass had attracted scavengers, including coyote and marten (as recorded earlier on a trailcam). By now, nothing was left but scattered bones, hooves, and hair. This beast had been an old fellow, with badly worn teeth, although his stomach had had some food in it. Out on the bare sand flats, we saw some prodigious brown bear tracks, accompanied by those perhaps of a two-year old.

A good visit in excellent company!

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Good finds in Gustavus

A summertime walk through woods and meadows is almost always good—birds are singing, flowers are blooming, and there’s always nice fresh air. But sometimes all the little pleasures form a base on which rest some observations of particular interest. Here are a few good ones from a recent trip to Gustavus.

–Dandelions had mostly gone to seed, so fields that had been golden with flowers were now white with plumes on mature seeds ready to disperse on the wind. But here and there we found a laggard flower, still yellow and conspicuous on the background of white. On one of these late bloomers there was a bumblebee, a strangely immobile bee. Looking more closely, we saw a yellow crab spider with the bee in its clutches. Crab spiders are venomous (to insects), immobilizing their prey and then sucking out the juices. Dinner was in progress and the bee would fly no more. Crab spiders are generally ambush-predators; some of them lurk on flowers in hopes that a tasty insect will alight. The color of the spider often matches the color of the flower on which it awaits a victim.

photo by Kerry Howard

–The ponds at the gravel pits are a great place to see shorebirds, swallows, and kingfishers. There were sticklebacks swimming around and, in June, there were gravid females full of eggs. One pond held many thousands of toad tadpoles, swarming in the shallows where the water temperature was salubrious. They came in a variety of sizes—some at least six times bigger than the smallest. A female toad can lay thousands of eggs; the hordes of tadpoles that we saw undoubtedly had many mothers, which probably laid their eggs at somewhat different times, accounting for the size variation. None of them had begun to transform into toadlets; no little legs were visible. A dense pack of tadpoles clustered around a silvery object, each one trying to grab a mouthful. Looking closely, we discovered that the silvery object was a dead stickleback. Toad tadpoles commonly feed on algae and detritus, but they are also known to scavenge carrion and even the dead bodies of their comrades. Toad (and frog) populations have declined dramatically almost everywhere, and it was heartening to see this large aggregation of juveniles.

–Gustavus is noted for (among other things) its wide sandy beaches. On our way out to one of them, we heard some odd sounds, rather like the hooting of a small owl. As we listened carefully, however, it became apparent that several snipes were performing their aerial territorial display. It’s called ‘winnowing’, and it’s made by the rapid passage of air over the spread-out tail feathers, usually as the bird dives toward the ground from high in the air. Usually the male does this but sometimes females do too. I hadn’t heard this display for a long time and it was a gladsome sound.

–Out on the sandy beaches we found windrows of long, flexible tubes that were the former housing of certain marine worms. The worms were long gone, possibly starved at the end of winter when food is scarce. Then the tides presumably stripped the empty tubes from their attachment points and piled them up on the beach. This observation stimulated a lot of conjecture but no concrete answers.

–On the vegetated sand dunes there were lots of the strange little ferns called moonworts (a.k.a. grape ferns). They don’t look at all like ferns to the layman’s eyes, because the fronds are generally not very lacy or branched. We found many that appeared to be the common moonwort, but there were also a few much more robust individuals that were certainly a different species. On one of the postglacial-uplift meadows we found another kind, one that is now classified in a different genus; the fronds on this one (so-called rattlesnake fern) are somewhat more ‘fern-y’. All three of these are widespread species in North America and even beyond, but they are so odd that it is always fun to find them.

–The pilings of the public dock usually offer something even to a casual observer. Enormous white anemones, far larger than any we usually see in the rocky intertidal zone, wave their tentacles if the tide is in. Sea stars cling to the vertical surfaces too, but the largest ones have trouble hanging on when the tide goes out and leaves them above the waterline. Colorful sponges and tunicates add to the array. Sometimes there’s a giant whelk laying a coil of egg cases. Small fish sometimes gather under the docks and are visible between the pilings. And while one inspects the fauna on the dock, barn swallows are swooping overhead, gathering flies and mosquitoes for their chicks.

–We searched for lady’s slipper orchids (of which more, later). One clump of flowering stems still included a stalk with last year’s seed capsule, well dried. Someone opened the capsule to see if any seeds were left and found, instead, a tiny spider guarding her minute ball of orange eggs. We were sorry to have destroyed her safe-house!

–Sweetgrass grows in many Gustavian meadows and some of us stopped to braid some stems. Braided sweetgrass is used, especially by Native Americans, to construct baskets and decorative items, and we had to try just a simple braid. As we concentrated on our task, we heard thundering hoofbeats, getting rapidly closer. Turning around, we saw a fast-trotting female moose, followed by a young calf. They were so intent on getting away from whatever startled them that they ignored us and passed by, barely thirty feet away, and off they went, full tilt.