December 1940

YOSEMITE NATURE NOTES VOL. XIX,

December, 1940 No. 12 Dana Glacier

THE PUBLICATION OF THE YOSEMITE NATURALIST DEPARTMENT AND THE YOSEMITE NATURAL HISTORY ASSOCIATION

Published Monthly

VOL. XIX DECEMBER, 1940 NO. 12 THE ICE CAVE OF DANA GLACIER

By Ranger Naturalist Carl W. Sharsmith Within the past few seasons ice spallings had been determined by ice cave has developed in the Dana horizontal compressional layers sep- Glacier. A visit to this cave was one arating along "joint" planes. Al- of the objectives during a natural- though these layers were ten or ist conducted trip to the Dana Glacier from Tuolumne Meadows late have more inches in thickness, they might have represented annual increment in July, 1940, participated in by strata. thirty-two enthusiastic and appreci- The most interesting feature, and ative visitors. Situated on the right that which made the cave quite re- side as one came into view of the markable, was the curiously fluted glacier, its external appearance character of the sides and roof. It seemed unpromising. Nevertheless, was evident at once that this fluted it permitted an intimate view of the condition was due to the movement interior of a glacier such as is sel- of the ice. In its passage over the dom available to explorers of Yo- bed rock, the bottom of the glacier semite icefields. conformed to the irregular shape of The dimensions of the cave were its bed. This shape was continued about seventy-five feet in length, in the free portion now over-arch- and about fifty feet in greatest ing to form the walls and roof of width. On one side a low opening the cave, the flutings retaining ex- extended toward an unknown depth. actly the irregularities of the last The floor was of bed rock, which rocks overridden. Thus the likeness slanted upward from the entrance of the walls and roof to some giant quite steeply until it met the ice roof "pulled candy" was striking. Fur- at the back. The roof was thin in ther demonstration of motion lay in places, showing a pale blue trans- some boulders embedded in the lucence. One portion of the roof had roof. Their bottoms were planed spalled off like exfoliation sheets in flush with the ice, and a trail of gla- massive granite, and great jagged cial flour adhered to the roof be- chunks of clear ice littered the floor tween the boulders and the bed- of the cave like talus blocks. These rock several feet away. These were

" faceted" boulders just fresh from up Glacier Canyon between the east the mill, but still in the grip of the face of Mount Dana and Dana Plateau ice. Plateau, a distance of about four miles. The walls of the cave were nar- There is no trail and the going is rowly banded horizontally, demon- rough in places, but the reward for strating the annual increment of the geologically minded is abundant. snowfall, but the compact nature of The ice cave is one of the the ice itself, as well as its peculiar many features of this most accessible ly crystalline structure, was evi- visible of the glaciers of the Yosemite dence of great pressures and stresses. High Sierra. The cave is, of course, and repeated molecular rear- subject to many alterations in form rangements. It possessed all the characteristics of old glacier ice. from that described above, so thin The Dana Glacier was easily to be its continued observation will be reached from Tioga Pass by hiking considerable interest.

LIFE CYCLE OF TOADS IN YOSEMITE VALLEY

By Charles H. Martin One of the first things I observed The males of the species came after starting my work at the Yo- first, and their songs were heard semite Museum the middle of April in all the meadows at night—even 1940, was the migration of two am- above the rushing river and the phibians, the Pacific Tree-toad (Hyla crashing waterfalls. There were conregilla Baird and Girard) and the constant chirping notes ringing from the California Toad (Bufo boreas halophilus Baird and Girard) to the still the throaty murmurs in lieu of songs, meadow pools in Yosemite Valley. from the California Toads. The fe- These pools were forming from high males soon came and joined them water in the Merced River and its the still pools and ditches became tributaries, due to the melting snow cluttered with the bodies of these pack. The toads were commonly amphibians, and the air vibrant with seen as they crossed highways and their songs. This symphony of the trails heading for these meadow toads lasted through April and the pools. For several months they had first weeks of May– much later than been dormant in their hide-away, in the lower altitudes of the state but now the snows were gone from Here, the season is almost a month the valley floor, and they were leav- later in starting as compared with ing their ground burrows, their those sections of the state which are cracks in rocks, and their places lower and warmer. Mating was in from under logs to go down to the process, and the female Tree-toad meadows and mate. laid her fifty or so eggs in jelly-like

masses, while the California Toad laid her approximately 10,000 eggs long strings of jelly-like substance. Soon the egg laying was completed, and by the middle of May, I found the toads leaving the meadows for their retreats again. A few remained in the meadows, but kept so well hidden during the day that I knew they were there only by their songs at night. However, the large majority of the toads returned to the slopes and mountains, to gardens and to wooded areas, and to rocky streams to live their sheltered lives until next spring. PACIFIC TREE TOAD (Hyla regilla) Vocal pouch and egg mass Towards the end of May, the eggs hatched and the pools and streams were teeming with small larvae of tadpoles. The larvae of the Pacific Tree-toad are a dark brown in color with heavily speckled black dots and an under surface of white, while the California Toad larvae are uniformly dull black with an under surface only slightly paler. I collected the first series of larvae about the first of June while they were sucking algae and humus from the sides and bottoms of the pools. Already the larvae of the Hyla regilla were much larger than those of the Bufo boreas halophilus, despite the greater size of the California Toad in the adult stages of these species. The metamorphosis is rapid, and several of those specimens taken had hind limbs developed. But the development of these animals must be rapid because by this time of year the excess supply of water flowing into the valley has been stopped. The pools, no longer being fed by the rivers and streams have begun to dry under the hot rays of the sun, and as these pools become smaller, there is a race between the hot sun and the larvae to determine whether or not the larvae will complete development before the pools go dry. As early as June 7, I encountered a spot in the meadows southwest of the Old Village which proved to be a death trap for thousands of larvae of the California Toad. As late as the last of May, this area had been filled with swampy pools, but when it started drying the water rapidly vanished, and at least 5,000 larvae were baked to

death in an area 4 feet by 6 feet as the water in their pool seeped away. By the first weeks of July I noticed quite a few toads that had completed their development and as I walked through the meadows they jumped through the grass or into the water. On July 11 another visit to the meadows southwest of the Old Village showed that the pools here were drying rapidly, and everywhere were damp, muddy spots with the bodies of thousands of larvae in them. Only one pool remained at the base of a huge boulder, and in this water the larvae were so crowded that the pool was literally black with them; half of them dead and the other half dying. One could easily see that all the waters in these meadows would be gone before the life within it had developed enough to live out of the water. However, the picture was not so dark for those larvae living in the pools north of the Old Village, for here the pools were deeper and lasted longer, and over half of the amphibians in them were able to complete their metamorphosis before the pools were completely dry. When I visited the meadows on the sixteenth of August there was no water in evidence. Streams were dry, and the pools held water only in their muddy bottoms. But in these damper places were hundreds of young toads, largely Pacific Tree-toads, as many as six to the square foot, that had won the race against the sun. A collection was made of the various stages in the development of both of these toads, which is now in the museum's alcoholic collection So it is that the pools and streams in the meadows which once nursed hundreds of thousands of amphibian larvae are now gone, but before they dried up they were able to give life to enough toads to perpetuate their species. It is therefore quite evident why toads lay so many eggs. It is necessary for millions of young to be started in order that a few will survive to reproduce their species. After an other winter of snow and rains, these pools will again be filled, and the process of housing and destruction of larvae will again be repeated. Thus nature gives life and takes it away, but always there is life.

NATURE NOTELETS

By Ranger-Naturalist Mowbray On July 8, 1940, I found a dead Rubber Boa on the Big Oak Flat Road a short distance above the long tunnel. The length which this species attains is usually less than 24 inches, but this particular specimen measured 28 inches in length and was probably longer before killed as a part of the head was missing.

A NEW RODENT FOR YOSEMITE NATIONAL PARK

By Ranger Naturalist Vincent Mowbray The Gilbert White-footed Mouse at this point is about 2400 feet. All (Peromyscus truei gilberti) has been three of these individuals were ad- suspected of occurring within the ult and in breeding condition. The boundaries of Yosemite National female contained three well-de- Park, but it was not until this year veloped embryos, and the testes of that any specimens were obtained the two males were descended and to uphold this suspicion. On July 6, much enlarged. In Grinnell and 1940, two of these mice were cap- Storer, "Animal Life in the Yosemite " tured at Miguel Meadows, elevation they say, "The breeding season of 5200 ft., by David Dunn and Bob this mouse is not known with any Stebbins both members of the Yo- certainty... " These meager data semite School of Field Natural His- point to a breeding season three tory. One of these specimens, a fe- months in extent (May to July), with male, is apparently a young indi- the probability that it is of some- vidual as it has the blue-gray col- what longer duration. The capture oration to the pelage which is typi- of these three individuals on Sep- cal of a juvenile animal. The other tember 19, all of them in breeding specimen is an adult though small condition would seem to indicate male. The next record for this spe- that the breeding season of this cies in the park is of three speci- mouse extends well on into the fall. mens obtained by the writer on Sep- The following chart shows the tember 19, 1940. These last three measurements in millimeters of this specimens were obtained near the mouse as given by Grinnell and All-Year-Highway to Merced, about Storer and also the measurements 100 yards within the boundary of of the five specimens in hand. One Yosemite National Park. Twenty-five of the last three captured had lost traps were set out on a dry hillside at least half of its tail prior to its near the highway, and the total capture so total length and tail catch was three mice. The elevation measurements were not possible. Grinnell and Storer Measurements 1. Miguel Mdws. Juv. Fe. 2. Miguel Mdws. Ad. M 3. El Portal Ad. Fe. 4. El Portal Ad. M. 5. El Portal Ad. M. Total Tail Hind Foot Ear 182-221 94-111 23-25 20-26

THE DOTTED CANYON WREN COMES BACK

By Ranger Naturalist Enid Michael The Dotted Canyon Wren, once a common bird in all the rock slides about Yosemite Valley has been strangely rare these last several years, and it is a pleasure therefore to report a slight but apparent increase in the number of birds this season. In three different sections of the valley, Canyon Wrens have been seen and heard. So late in the season as July 29, three different individuals were heard in song : one bird at Rocky Point, one bird on the talus heap at the foot of the Royal Arches, and a third bird on the rock slide back of Camp 19. There is the hope that Canyon Wrens may once more become permanent residents in Yosemite Valley. The Canyon Wren is one of our sweetest singers and better still so unique is its song that when once heard it is not likely to be forgotten, or to be confused with the song of any other bird. His song comes tumbling down the scale like the bubbling voice of an eager brook that joyously bounds down hill. Because of its peculiar feeding habits the Canyon Wren has no competition along the forage lanes and because of these habits, it may enjoy a prosperous winter in the Yosemite Valley even in seasons of heavy snow. In the dark caverns among the great boulders that are piled at the base of the cliffs the Canyon Wrens find their food and even in winters of heavy snow the forage lanes among the boulders are still accessible to the wrens.

CASSIN'S VIREO FEEDS COWBIRD

By Park Naturalist C. A. Harwell On June 25, 1940, while conducting the Yosemite School of Field Natural History on a field trip, we saw an immature Dwarf Cowbird near the shore of Mirror Lake. The young of this species in Yosemite Valley is worthy of observation, so we watched to see what would happen. The young bird was walking about under an Oak picking at food on the ground. It seemed to pay little attention to our close approach. Soon a male Cassin's Vireo approached to within 10 feet of the Cowbird, and seemed quite alarmed about the audience situation. Finally by call notes and song fragments the Vireo succeeded in attracting the young bird to the lower limbs of an Oak, then the parent Vireo led the Cowbird in a 40-foot flight to another Oak, where the monstrous looking young was fed by both male and female Cassin's Vireos. The nature of the food was not seen.

FIREFALL FROM HALF DOME

By Ranger Naturalist Russell L. Lewis

In the early days of white man In Yosemite Valley the now world famous Half Dome was known as one mountain that would never be climbed by man. Since the first ascent in 1875, there have been literally thousands of Yosemite visitors who have scaled the granite dome. On Saturday evening, August 17, Ranger Naturalist Ernie Payne and I had one hundred ten people at a campfire program at the very top of Half Dome. We had left Happy Isles (Pleasant Point as one lady insisted on calling it) at noon, and the last of our party arrived at the summit by eight in the evening. The party included a lady from Holland, youngsters only nine years old, and other visitors from all parts of the United States. The lady from across the Atlantic reminded us of the hostilities over there and of our great fortune in being able to enjoy both the freedom and beauties of our great National Parks. It reminded us, too, of the generous and foresighted individuals who originated and developed this "idea" of a National Park where all people may enjoy the beauties of nature. As there is little vegetation on the dome, it was necessary for each of us to carry up a stick for the campfire. The unique place for a campfire and the spectacular view of Firefall were only two of the features of the evening for friends in many places saw us on Half Dome and made their identity known by signalling with flashlights. Ranger Naturalist Heil and his party of seven-day hikers signalled to us from a little dome near the May Lake High Sierra Camp which is nearly eight airline miles away. The operators of the slide projectors at the Ahwahnee Hotel and at Camp 14 turned their lights so as to signal to us. Mrs. Payne and Mrs. Lewis signalled to us from the Wawona Tunnel which is also nearly eight miles away. We could see the blinking flashlights of the people who were at Glacier Point. Finally, another hiking party had a campfire on top of Cloud's Rest. After our party was satisfied with the views of firefall, light signals from friends on distant peaks, and the achievement of having climbed

a world-famous dome, we started time that white flowered Red Heath- the trek back to Yosemite Valley in er has been observed in Yosemite the light of full moon. Although National Park. Collected specimens some of the weary hikers plodded turned from white to faintly pink on on until the early hours of Sunday pressing and drying. They have morning, none apparently regretted been placed in the herbarium of the the inspirational but tough climb. Yosemite Museum,

WHITE-FLOWERED RED HEATHER

Ranger Naturalist C. W. Sharsmith The Red Heather (Bryanthus breweri Gray) is so named because of its red or deep pink flowers. In a little valley at the north base of Triple Divide Peak above Washburn Lake, members of the 1940 Yosemite School of Field Natural History found a patch of this heather several yards in extent which possessed pure white flowers. Surrounding this locality were acres of the normal red form. Such a case of albinism in a normally colored flower, while not unusual in nature, is apparently infrequent in this Red Heather. This appears to be the first

NATURE NOTELET

By Ranger Naturalist G. A. Petrides The second and third specimens of the Golden Long-eared Bat (Myotis evotis chrysonotus J. A. Allen) ever to be recorded in Yosemite National Park, to the best of the author's knowledge, were captured in the museum building on August 3 and September 14, 1940. Like the first specimen taken on June 27, 1927, the second animal captured was an adult female. Concentrations of vascular tissue in the right horn of the uterus seemed to indicate the birth of two young earlier in the summer. The third individual was probably an immature male, as judged from the small size of the testes and the condition of the skull and teeth. The large ears and golden fur of this species make it easy of identification, but like many other species of bats, little is known of its habits or even its distribution within the park. However, this species is undoubtedly of moderately common occurrence in the Yosemite region despite the failure of Grinnell and Storer to mention it in their "Animal Life of Yosemite," published in 1924. Further data in regard to all species of Yosemite bats are badly needed.

Digitized by Yosemite Online Library Dan Anderson