Frogs are perfect thermometers.

April 30. 

April 30, 2018

P. M. – I carry the rest of my little fishes, fifteen or twenty, to the cold pool in Hubbard's ground. They are about a quarter-inch long still, and have scarcely increased in length. 

I learn that one farmer, seeing me standing a long time still in the midst of a pool (I was watching for hylodes), said that it was his father, who had been drinking some of Pat Haggerty's rum, and had lost his way home. So, setting out to lead him home, he discovered that it was I. 

I find a Fringilla melodia nest with five eggs. Part, at least, must have been laid before the snow of the 27th, but it is perfectly sheltered under the shelving turf and grass on the brink of a ditch. The snow would not even have touched the bird sitting on them. 

It is much warmer, and now for the first time since April 23d I find frogs out. (Perhaps I could have found some yesterday.) 

I noticed one of the large scroll ferns, with its rusty wool, up eight inches on the 28th. 

See a white-throated sparrow by Cheney's wall, the stout, chubby bird. 

After sundown. By riverside. —The frogs and toads are now fairly awake. Both are most musical now at evening. I hear now on various sides, along the river and its meadows, that low, stertorous sound, like that of the Rana halecina, – which I have heard occasionally for a few days. (I also hear it in Stow's field by railroad, with toads’ ringing.) It is exceedingly like the note of the R. halecina, yet I fancy it is some what more softly purring, with frequently a low quivering, chuckling, or inquisitive croak, which last takes the place of the bullfrog-like er er er of the halecina. This is the only difference between it and the halecina that I am sure of. The short quivering croak reminds me of the alarm (?) note of the hylodes. I suspect it is the R. palustris, now breeding. 

I hear no snipe. 

Frogs, etc., are perfect thermometers. Some that I had in a firkin were chilled to stiffness, while their fellows buried themselves again in the mud of the meadows; i.e., in a cold night at this season they are stiffened in a tub of water, the small R. palustris, not being able to bury themselves in mud. They appear to lose their limbs or portions of them, which slough off in consequence.

H. D. Thoreau, Journal, April 30, 1858

I find a Fringilla melodia nest with five eggs. See June 14, 1855 ("A song sparrow’s nest in ditch bank under Clamshell, of coarse grass lined with fine, and five eggs nearly hatched and a peculiar dark end to them."); June 9, 1855 ("A song sparrow’s nest low in Wheeler’s meadow, with five eggs, made of grass lined with hair."); May 27, 1856 ("Fringilla melodia’s nest in midst of swamp, with four eggs, made partly of usnea; . . . eggs with very dark blotches"); May 31, 1856 (“A ground-bird’s nest (melodia or graminea.), with six of those oblong narrow gray eggs speckled with much brown at end. ") See also A Book of Seasons, by Henry Thoreau, the Song Sparrow (Fringilla melodia)

See a white-throated sparrow by Cheney's wall, the stout, chubby bird. See  April 25, 1855  ("The handsome and well-marked bird, the largest of the sparrows, with a yellow spot on each side of the front."); April 23, 1856 ("A plump-looking bird and, with its bright white and yellow marks on the head distinctly separated from the slate-color, methinks the most brilliant of the sparrows.")

Standing a long time still in the midst of a pool watching for hylodes. See April 18, 1858 ("All that is required in studying them is patience"); and  note to March 27, 1853 ("Stood perfectly still amid the bushes on the shore, before one showed himself; finally five or six, and all eyed me, gradually approached me within three feet to reconnoitre, and, though I waited about half an hour, would not utter a sound.")

It is some what more softly purring, with frequently a low quivering, chuckling, or inquisitive croak. See  May 23, 1856 ("The ring of toads is loud and incessant. . . .At the same time I hear a low, stertorous, dry, but hard-cored note from some frog in the meadows and along the riverside; often heard in past years but not accounted for. Is it a Rana palustris?"); May 8. 1857 ("It is an evening for the soft-snoring, purring frogs (which I suspect to be Rana palustris). . . . Their croak is very fine or rapid, and has a soft, purring sound at a little distance.") A Book of the Seasons,  by Henry Thoreau, the  Rana palustris Pickerel frog (Lithobates palustris)

Snows hard in afternoon and evening. Quite wintry.

April 27 

April 27, 2018

It has been so cold since the 23d that I have not been able to catch a single frog, have hardly seen where one jumped, as I walked through the meadows looking for them, though in some warmer places I heard a low stertorous R. halecina-like note from a few. 

The tortoises are stirring much more. 

Frogs appear to love warm and moist weather, rainy or cloudy. They will sit thickly along the shore, apparently small bullfrogs, etc., R. palustris. 

My young fishes had the pectoral fins and tail very early developing, but not yet can I detect any other fins with my glass. They had mouths, which I saw them open as soon as hatched, and more and more a perch-like head. I think that with Hoar's microscope I detected two dorsal fins such as the perch have. When I put them suddenly in the sun they sink and rest on the bottom a moment. 

In the French work for schools of Edwards and Comte, it is said that the perch spawns not till the age of three years, and in the spring. “The ova are joined together by some glutinous matter in long strings (codons) intertwined with the reeds.” (Page 36.) 

I noticed yesterday that again the newly laid spawn at the cold pool on Hubbard's land was all gone, and that in the larger pool south of it was much diminished. What creature devours it? 

Snows hard in afternoon and evening. Quite wintry. About an inch on ground the next morning.

H. D. Thoreau, Journal, April 27, 1858

It has been so cold since the 23d that I have not been able to catch a single frog. See April 24, 1858 (“This shows how sensitive they are to changes of temperature. Hardly one puts its head out of the water, if ever he creeps out the grassy or muddy bottom this cold day. ”)

The newly laid spawn at the cold pool on Hubbard's land was all gone. See April 22, 1858 (“The spawn of April 18th is gone! It was fresh there and apparently some creature has eaten it.”)

Snows hard in afternoon and evening. Quite wintry. See note to April 2, 1861 ("A drifting snow-storm, perhaps a foot deep on an average.”)

I go at 8 A.M. to catch frogs to compare with the R. palustris.

April 24.

A cold northwest wind.

April 24, 2018

I go at 8 A.M. to catch frogs to compare with the R. palustris and bull frog which I have, but I find it too cold for them. Though I walk more than a mile along the river, I do not get sight of one, and only of one or two turtles. Neither do I find any more frogs (though many Emys picta) at 4 P. M., it being still cold. 

Yet the frogs were quite numerous yesterday. This shows how sensitive they are to changes of temperature. Hardly one puts its head out of the water, if ever he creeps out the grassy or muddy bottom this cold day. 

That proserpinaca deserves to be named after the frog, — ranunculus, or what-not, — it is so common and pretty at the bottom the shallow grassy pools where I go looking for spawn. 

It is remarkable that I see many E. picta dead along the shore, dead within a few weeks apparently, also a sternothaerus. One of the last, alive, emitted no odor to-day. 

I find washed up by the riverside part of a pale-greenish egg-shell bigger than a hen’s egg, which was probably the egg of a duck laid on the meadow last year or lately. 

There is an abundance of the R. halecina spawn near the elm at the hill shore north of Dodd's. It is now semiopaque, greenish, and flatted down and run together, mostly hatched; and a good deal has been killed, apparently by the cold. The water thereabouts is swarming with the young pollywogs for a rod about, but where have all the frogs hidden themselves? 

E. Hoar saw the myrtle-bird to-day. 

The pollywogs must be a long time growing, for I see those of last year not more than two inches long, also some much larger. 

The hatched frog-spawn is quite soft and apparently dissolving at last in the water. Yet possibly that mass of jelly once brought me on a stake was this jelly consolidated. 

I find that my fish ova were not all killed some weeks ago in the firkin, as I supposed, for many that were accidentally left in it have hatched, and they bore the cold of last night better than those hatched earlier and kept in the larger vessel (tub), which froze but thinly, while the firkin froze a quarter of an inch thick last night.

H. D. Thoreau, Journal,  April 24, 1858

Many Emys picta. See April 24, 1856 ("A young Emys Picta one and five eighths inches long and one and a half wide. . . . already covered with some kind of green moss."); See also March 28, 1857 ("The Emys picta, now pretty numerous . . .He who painted the tortoise thus, what were his designs?");  April 22, 1858 ("The Emys picta are evidently breeding also.") and  A Book of the Seasons, by Henry Thoreau, the Painted Turtle (Emys picta)

A sternothaerus emitted no odor to-day. See April 1, 1858 ("I see six Sternothaarus odoratus . . . and smelt of five of these, and they emitted none of their peculiar scent! It would seem, then, that this may be connected with their breeding, or at least with their period of greatest activity.");   June 16, 1858 ("Two sternothaerus which I smell of have no scent to-day.  ")  See also A Book of the Seasons, by Henry Thoreau, the Musk Turtle (Sternothaerus odoratus )

That proserpinaca [palustris] deserves to be named after the frog:  Rana palustris, the pickerel frog; Proserpinaca is a genus of flowering plants found in aquatic or terrestrial wetland habitat  Palustris is a Latin word meaning swampy or marshy often used for species names to refer to the typical habitat of the species. ~ Wikipedia

There is an abundance of the R. halecina spawn near the elm at the hill shore north of Dodd's. The water thereabouts is swarming with the young pollywogs for a rod about. See April 14, 1858 (“My Rana halecina spawn in tumbler is now flatted out and begins to betray the pollywog form.”); 

I find that my fish ova were not all killed some weeks ago in the firkin, as I supposed. See note to April 16, 1858 ("I think that the spawn could not have been laid long when I found it April 3d, . . .My fish ova in a tumbler has gradually expanded ... (Some are still in the egg on the 18th.)")

Fish embryos suddenly hatched

April 16

My fish ova in a tumbler has gradually expanded till it is some three sixteenths of an inch in diameter, and for more than a week the embryos have been conspicuously active, hardly still enough to be observed with a microscope. Their tails, eyes, pectoral fins, etc., were early developed and conspicuous. They keep up a regular jerking motion as they lie curved in the egg, and so develop themselves. 

This morning I set them in the sun, and, looking again soon after, found that they were suddenly hatched, and more than half of them were free of the egg. They were nearly a quarter of an inch long, or longer than the diameter of a perfect egg. The substance of the egg-shell seemed to have expanded and softened, and the embryo by its incessant quirking elongated it so that it was able to extend itself at full length. It then almost incessantly kept up a vibratory motion of its tail and its pectoral fins, and every few moments it bunted against the side of the egg, wearing it away and extending it, till it broke through. Sometimes it got its head out first and then struggled many minutes before it escaped completely. 

It was a pretty sight to see them all rising immediately to the surface by means of the tail and pectoral fins, the first vibrating from one twentieth to one thirtieth of an inch, at an angle of about forty-five degrees, and then, ceasing their motions, they steadily settled down again. Think of the myriads of these minnows set free of a warm morning, and rising and falling in this wise in their native element!!

(Some are still in the egg on the 18th.) 

The incessant activity of these minnows, and apparent vigor, are surprising. Already they dart swiftly an inch one side like little pickerel, tender as they are, carrying the yolk with them, which gradually diminishes, as I notice, in a day or two after. They have no snouts yet, or only blunt and rounded ones. I have not detected any general resting even at night, though they often rest on the bottom day or night. 

They are remarkably aroused when placed in the morning sun. This sets them all in motion. Looking at them through a jar between you and the sun, a hundred at once, they reflect the colors of the rainbow, — some purple, others violet, green, etc., etc. It is a wonder how they survive the accidents of their condition. 

By what instinct do they keep together in a school? I think that the spawn could not have been laid long when I found it April 3d, it was so perfect and the embryo so slightly, if at all, developed. That was a sudden very warm day. In that case, they may be hatched in a fortnight. That appeared to have been a general breeding-place for this species of fish. I looked a good while on the 14th, but could find none near home. 

My hylodes in the tumbler will always hop to the side toward the window as fast as I turn it. 

We may think these days of the myriads of fishes just hatched which come rising to the surface. The water swarms with them as with the mosquito.

P. M. — To Conantum. 

The Rana sylvatica spawn at Hubbard's Grove begins to kick free. This is early. I put some in a bottle, which being shaken in my walk, I find the embryos all separated from the ova when I get home. These are now regular little pollywogs and wiggle about in a lively manner when the water is shaken. 

They are chiefly tail and head. They look like the samara of the ash, and in both cases this winged or feather-like tail it is that transports them. I can already see their little feet or fins. 

The bodkin-like bulb, considerably grown, in my tumbler and elsewhere, is probably the water-purslane. I see it floating free and sending out many rootlets, on pools and ditches. In this way it spreads itself. 

The earliest red maple I can see in this walk is well out, on the Hubbard Bridge causeway. Probably some was yesterday. 

I sat a long time by the little pool behind Lee's, to see the hylodes. Not one was heard there; only the skater insects were slightly rippling the surface, pursuing one another and breeding amid the grass. The bottom is covered with pretty proserpinaca. 

At length I see one hylodes with heels up, burying itself at the bottom. How wary they are! After nearly half an hour I see one sitting out on a blade of the floating purple grass, but down he goes again. They see or hear you three or four rods off. They are more active toward night.

H. D. Thoreau,  Journal, April 16, 1858


I think that the spawn could not have been laid long when I found it April 3d, it was so perfect and the embryo so slightly, if at all, developed. For more than a week the embryos have been conspicuously active, as they lie curved in the egg. This morning I  found that they were suddenly hatched, and more than half of them were free of the egg. See April 3, 1858 (“When returning, we discovered, on the south side of the river, just at the old crossing-place from the Great Meadows, north of the ludwigia pool, a curious kind of spawn. It was white, each ovum about as big as a robin-shot or larger, with mostly a very minute white core, no black core, and these were agglutinated together in the form of zigzag hollow cylinders, two or three inches in diameter and one or two feet long, looking like a lady's ruff or other muslin work, on the bottom or on roots and twigs of willow and button-bush, where the water was two or three feet deep. The greater part lay on the bottom, looking like a film, these cylinders being somewhat coiled about there. When you took it up, the two sides fell together, and it was flat in your hand like the leg of a stocking. In one place there were a dozen very large red-bellied and brown-backed leeches in it, evidently battening on it. ); April 7, 1858 ("I brought home t... two kinds of spawn in a pail. ... The other (probably fish) spawn is seen to be arranged in perfect hexagons; i. e., the ova so impinge on each other; but where there is a vent or free side, it is a regular arc of a circle. Is not this the form that spheres pressing on each other equally on all sides assume? I see the embryo, already fish-like (?), curved round the yolk, with a microscope.”); April 14, 1858 (“My Rana halecina spawn in tumbler is now flatted out and begins to betray the pollywog form. I had already noticed a little motion in it from time to time, but nothing like the incessant activity of the embryo fishes. . . .At Ed. Hoar's in the evening.. . .. with his microscope I see the heart beating in the embryo fish and the circulations distinctly along the body.”); April 22, 1858 (“The spawn of April 18th is gone! It was fresh there and apparently some creature has eaten it.”)April 24, 1858 (“I find that my fish ova were not all killed some weeks ago in the firkin, as I supposed, for many that were accidentally left in it have hatched, and they bore the cold of last night better than those hatched earlier and kept in the larger vessel (tub), which froze but thinly, while the firkin froze a quarter of an inch thick last night.”); April 27, 1858 (“I noticed yesterday that again the newly laid spawn at the cold pool on Hubbard's land was all gone, and that in the larger pool south of it was much diminished. What creature devours it? ”); April 27, 1858 (“My young fishes had the pectoral fins and tail very early developing, but not yet can I detect any other fins with my glass. They had mouths, which I saw them open as soon as hatched, and more and more a perch-like head. I think that with Hoar's microscope I detected two dorsal fins such as the perch have. ”); April 30, 2018 ("I carry the rest of my little fishes, fifteen or twenty, to the cold pool in Hubbard's ground. They are about a quarter-inch long still, and have scarcely increased in length.”); June 16, 1858 ("Looking into Hubbard's Pool, I at length see one of the minims which I put into it. I brought the last here April 30th. It is now a little perch about an inch and a quarter long; it was then about a quarter of an inch long. I can now see the transverse bars a rod off. It is swimming actively round and round the pool, but avoids the quite shallow water of the edges, so it does not get landlocked or lost in the weedy overflowed edges. I put twenty or thirty into this pool in all. They grow very fast, then, at last.”)

The earliest red maple I can see in this walk is well out. See April 24, 1854 ("The first red maple blossoms — so very red over the water — are very interesting");. April 26, 1855 ("The blossoms of the red maple (some a yellowish green) are now most generally conspicuous and handsome scarlet crescents over the swamps.") See also A Book of the Seasons, by Henry Thoreau, The Red Maple

I sat a long time by the little pool behind Lee's, to see the hylodes. Not one was heard there; . . How wary they are! See March 31, 1857 (" If you do not listen carefully for its first note, you probably will not hear it, and, not having heard that, your ears become used to the sound, so that you will hardly notice it at last, however loud and universal.. . . The shrill peeping of the hylodes locates itself nowhere in particular.")

My hylodes in the tumbler will always hop to the side toward the window as fast as I turn it. See  April 15, 1858 ("Catch a peeper at Hayden’s Pool. I suspect it may have been a female . . . It was a pale fawn-color out of water, nine tenths of an inch long, marked with dusky like this though not so distinctly. It could easily climb up the side of a tumbler, and jumped eighteen inches at once.")