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THE EARLY BREEDING HABITS OF AMBLYS
ALBERT H. WRIGHT AND ARTHUR A. ALLEN
CASUAL observations made at Ithaca, during the past eight or nine years, upon the habits of Amblystoma punctatum have emphasized the need of an intensive study of the early breeding habits of this species, and consequently during the spring of 1908 considerable attention was given to this phase of its life history.
The best collecting ground for this species was found to be along the eastern border of the marsh at the head of Cayuga Lake where it is skirted by a state road and by the tracks of a trolley line. Here it is necessary for the salamanders from the hill, on their way to suitable breeding grounds, to cross the tracks and in so doing many are killed by the passing cars. Heretofore, it was believed that the majority came from the ravines which cut through the hill in this locality. To test this, a trap was placed at the mouth of one of the culverts under the road. The trap yielded only eight specimens during the ten days in which the species was migrating. It would, therefore, seem that the salamanders came mainly from the hill itself. For the study of spermatophores and eggs ponds on the hilltop near the university proved most fruitful. Six ponds were visited daily. In these, countless spermatophores and several hundred bunches of eggs were deposited. A chart of each pond was prepared and upon this, for future reference, the position of sev. eral areas of spermatophores and each bunch of eggs were indicated with the date of deposition.
The first appearance from hibernation for this species from 1903 to 1908 follows:
1903, March 13.
1906, March 28.
In 1908 the first appearance occurred the evening of March 23, when the maximum and minimum air temperature, were 47° and 42° F. The water temperatures of the two ponds under observation on the following morning were 42° and 48° F., respectively. On the above dates of first appearance from 1903 to 1908, the U. S. Weather Bureau Station at Ithaca obtained the following maximum and minimum air temperatures:
From this it is obvious that a temperature approximating 50° F. or more almost invariably caused the species to emerge.
To verify this conclusion, a careful record of the migration across the railway in 1908 was kept and a summary follows in tabular form:
In this table as in the preceding 50° F. appears the normal effective temperature of migration. The crest
? Climatological Report for March, 1908. New York Section of the Climatological Service of the Weather Bureau in Cooperation with Cornell University. By W. M. Wilson, p. 19.
of the migration in 1908 came when the maximum air temperature ascended to 60° or 70° F. In two other years the same conditions obtained as shown in the accompanying data:
The males begin the migration, as the following table will indicate:
Number Captured Alive.
Date (1908). March 26, March 27, March 28, April 1,
Number Killed. 15 males.
5 males, 4 females. 10 males, 14 females.
6 males, 3 females. 12 males, 19 females. 7 males, 10 females.
Thus we see the males began the migration. The next evening, the females appeared in small numbers and the third evening they predominated and continued thus for the remainder of the migration.
In 1908, the migration each evening across the railway began between 7:30 and 8:00 o'clock. By means of an acetylene lamp, the salamanders were observed crawling along close to the rail, often following it for some distance. At times they were seen attempting to cross the track by raising themselves erect on their tails. Even with this aid, scarcely more than the head came above the rail. In this position they often remained until crushed by the passing cars. Generally, however, they followed along the rail until they came to the joints, where the projecting bolts enabled them to work their way over.
The evening upon which spermatophores were first deposited, two salamanders were seen “nosing” each other, and one of the two depositing spermatophores. Neither was captured, and so to determine if this were a part of the regular courtship of the species, several salamanders collected along the track were taken to the laboratory
and placed in jars as follows: Jar No. 1, seven males; No. 2, several each of males and females; No. 3, a male and a female. These specimens had not reached the water, and were carried to the laboratory in a dry bag. The temperature of the water in the jars was 65° F., or fifteen to twenty degrees warmer than that in the ponds.
The seven males of jar no. 1 showed no excitement and deposited no spermatophores until a day or two later. Then, the total of spermatophores for the whole seven was much less than that deposited by the single male of jar no. 3.
In jar no. 2 the males and females became excited the moment they were placed together and many spermatophores were deposited at once. This experiment was repeated the following evening with a different set of salamanders and the males began to deposit spermatophores within fifteen minutes after being placed with the females. No eggs were deposited earlier than two days after the deposition of the first spermatophores.
In jar no. 3 the male, at first, showed no signs of excitement, but upon coming in contact with the female, he became very restless, and “nosed” her about in a definite manner. It seemed to be the object of the male to bring the top of his head in contact with the venter of the female. The throat region of the female seemed to be preferred, although he often began in the cloacal region or even at the tip of the tail and rubbed the dorsolateral part of the head along her whole ventral side. After each performance of this kind, the male swam away and grasped one of the sticks with its hind legs, bringing the cloaca close to the stem. The tail quivered for a moment and, with an arching of the region just caudad of the cloaca, the vent was lifted from the spermatophore. Then, he immediately returned to the female and began again the “nosing” process. The time consumed in depositing a spermatophore varied from 3 to 16 seconds, the periods for thirteen consecutive depositions being: 5, 3, 6, 10, 13, 12, 7, 11, 12, 16, 11, 10, 10 seconds, respectively. In this way twenty-two spermatophores were deposited in 45 minutes.
Most of this time the female remained quiet. Three times, however, she slowly moved over a spermatophore until the vent rested upon it. Then the hind limbs closed about it. In this position the female remained, each time, for ten to fifteen seconds and apparently made no effort to take any portion of the spermatophore into the cloaca as does Diemyctylus. It seemed to us rather that there was a simple passage of the spermatozoa from the spermatophore into the cloaca of the female.
Evidently, then, the female must be present at the time the spermatophores are deposited and in this we find the explanation for the delay in deposition of spermatophores after the species has first appeared from hibernation. The males begin the migration but no spermatophores are deposited until the arrival of the females. In the spring of 1908 the migration began the evening of March 26, but spermatophores were not recorded until the morning of March 28, after the arrival of the females. With the arrival of the females and the ensuing courtship, spermatophores are deposited. These are usually found in stagnant or slowly moving water, four to twelve inches deep, though they are occasionally recorded in water one and one half to two feet in depth. They occur in groups numbering from 2 to 125, covering an area of one half to three feet square. The usual number in a group is between 30 and 50. The spermatophores and the spermatozoa recently described by Smith? need no discussion here.
After the first spermatophores are deposited, an interval elapses before the first eggs are recorded. In former years this interval has varied from a few hours to seven days and we had been led to believe that the females did not come to the ponds until their eggs were ripe. This belief is no longer tenable. After the cloacal
Smith, B. G., “ The Breeding Habits of Amblystoma punctatum Linn.," AMERICAN NATURALIST, XLI, No. 486, June, 1907, pp. 381-385.