Toads, sticklebacks, and aphids…

…in Gustavus

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!