NATIONAL PARK SERVICE Fauna of the National Parks of the United States No. 4 Ecology of the Coyote in the Yellowstone

DUCKS

DURING the summer there are several thousand ducks in Yellowstone. In August 1938 more than 200 ducks were on the open waters of Swan Lake and many others may have been out of sight in the vegetation. In another instance I saw more than a thousand on a single lake. Some of the species included in the summer population are: mallard, Barrow's golden-eye, American merganser, gadwall, blue-winged teal, green-winged teal, and harlequin duck. During the spring and fall numerous other species also stop on park waters.

Many ducks winter on the open waters. A count made between January 14 and 20, 1939, resulted in the following: mallard, 316; goldeneye (American and Barrow's), 556; merganser, 73; bufflehead, 78; and green-winged teal, 10. In addition, 241 Canada geese and 106 trumpeter swans were counted, making a total of 1,725 waterfowl. A similar count made in the winter of 1938 yielded a total waterfowl count of 1,618. These counts are incomplete but are roughly comparable. They at least indicate that there are many ducks wintering in Yellowstone.

The majority of the 5,086 coyote droppings were collected in areas where ducks were plentiful during the nesting season and could be expected to furnish an appreciable amount of coyote food. Special effort was made to obtain representative collections in the vicinity of duck nesting localities.

Of the 5,086 coyote droppings collected duck remains were present in 82, or 1.6 percent. The incidence of occurrence was about the same in the 2 years during which droppings were gathered. In addition to the foregoing 18 food items classified simply as "large bird" and 62 as "bird" may have included some duck remains, not recognizable as such. The remains of 11 of the ducks were recognized as those of mallard. Furthermore the following feather remains, in spots where ducks had been eaten, were found along the Firehole, Yellowstone, Madison, and Pelican Rivers: 13 unidentified ducks, 6 mallards, 3 green-winged teals, 1 gadwall, 1 bufflehead, and 1 goldeneye. These remains were found along about 40 miles of river banks and lake shores.

Evidence of duck nest raiding was very meager. Eggshell fragments, possibly those of ducks, were present in 10 droppings and a single duckling was present.

Droppings containing duck feathers were sometimes grouped near feather remains in one spot, suggesting that a single duck was represented in several droppings. As an example, at one such pile of feathers were three fresh coyote droppings, all containing duck remains. The following is also suggestive: On December 17, 1937, on the bank of Flat Creek in Jackson Hole, I found the carcass of a female mallard which a coyote had investigated. Pin feathers on the wing showed that the duck had died in late summer during the moult. Only a little of the breast was eaten. The coyote had gnawed lightly at the dried carcass, then left it. Two or three feathers in the coyote's trail 10 feet away probably had dropped from his lips. Judging from other observations it is possible that subsequently, each time the animal passed that way, it nibbled at the bird enough to swallow a few feathers, thus leaving feather records in several droppings.

An unknown proportion of the duck remains would represent carrion. Near several of the better duck waters are telephone wires which the ducks probably fly into occasionally and thus lose their lives or become severely injured. As mentioned elsewhere, several dead grouse were found which had flown into the buffalo pasture fence and a telephone wire. A robin had been killed flying into the same fence, and one evening, in the dusk, one of two robins struck the single telephone wire and fell to the ground with a thud. Since even bats do not always avoid objects, such as nets it seems probable that a swift flying flock of ducks might occasionally lose a member in this manner.

In the autumn, wounded or sick ducks apparently come into the park and are unable to leave, either dying or remaining on the waters in a flightless condition. Such ailing ducks would occasionally fall prey to coyotes or furnish a certain amount of carrion. Concerning wounded ducks, Assistant Chief Ranger Albert E. Elliott, (Yellowstone Nature Notes, January, 1937, p. 7) writes:

Since the lake and river (Yellowstone) have frozen over, it is possible to find among the waterfowl which are left here quite a number that have been wounded (outside the park) and are not able to continue on their southern flight. Many of these will fall easy prey to coyotes, otter, eagles, and other of their natural enemies during the course of the winter.

Kalmbach and Coburn (1937) found disability and mortality among ducks wintering in southern Idaho in 1937 and report that such mortality on wintering grounds is not unusual. Inspection of 2-1/2 miles of banks of the Portneuf River near Pocatello disclosed 75 dead ducks, and a number of dead ducks were found along several drainage ditches. These ducks were heavily parasitized and lead shot was present in some of the birds. In view of these findings it is not surprising that disabled birds are found in Yellowstone.

An interesting though probably a minor cause of duck carrion is mentioned by N. P. Langford (1870). He writes:

As we stood on the margin of this immense lake (Excelsior Geyser) a small flock of ducks came sailing down as if to alight; but as they skimmed the water (of a hot spring) a few inches above the surface, they seemed to scent danger, and with rapid flapping of their wings, all except one rose into the air. This one, in his descent, had gained too great an impetus to check his progress, and came down into the water, and his frantic efforts to rise were futile, and with one or two loud squawks of distress, which were responded to by his mates, who had escaped, he was a dead duck.

The extent of this kind of mortality is probably not great, and probably those scalded but still able to get away would be available to the coyotes. In the hot pools of Old Faithful I have seen duck and goose skeletons. Near a hot pool at Old Faithful in which lay the skeleton of a duck, Assistant Park Naturalist W. E. Kearns found a coyote dropping containing duck feathers; however, there was probably no connection in this case between the duck remains in the spring and the feathers in the dropping.

During the summer of 1937 I found the carcasses of three mallards and a merganser that had not been eaten, the carcass of a mallard that had been partially eaten by birds, and two complete skeletons of uneaten ducks. These seven carcasses, undiscovered by coyotes, suggests that there must be many others that they do find. During the fall the amount of duck carrion would probably be greater than during the summer because of the influx into the park of injured or sick ducks.

In the interpretation of field observations it should be kept in mind that other animals besides the coyote are potential predators on ducks. Mink and otter probably occasionally catch one, and the eagles, of both species, prey on ducks to some extent, I once saw what appeared to be a golden eagle in immature plumage sitting on a mallard not yet dead. At Old Faithful in April 1938 I found the wing of a bufflehead duck at the base of a telephone pole and a bird pellet containing duck feathers at the base of an adjoining pole. The duck may have been killed by a predator, or it may have flown into the wires and died from injuries. In the same region about a mile away another bird pellet was found containing duck feathers, and at Gibbon Meadows in the spring of 1937 two bird pellets contained duck feathers. I mention these other predators here to show that preying on ducks is distributed among a number of species, including the coyote.

During the winter of 1937—38 from 40 to 50 mallards and about as many goldeneye ducks spent the winter on 3 or 4 miles of the Gardiner River where coyotes were concentrated. Frequently I followed the shores of the river during the winter in search of duck remains but found none. Coyotes were apparently not molesting these ducks. A few ducks winter on the Yellowstone River between Gardiner and Tower Falls but no indication of predation was found along this stretch of water.

Rangers report some duck predation by coyotes in winter but from all I can gather this is not serious. Coyote trails are frequently found along the open water but these animals would probably follow water courses in their travels if ducks were entirely absent, for streams are natural highways for many species. One such trail was reported to me and an informant conjectured that probably the coyotes were here persistently hunting the ducks in the stream. I investigated, picked up a dozen droppings along the beaten trail, and found that they all contained elk hair.

In late November 1938 I saw a pair of mallards on a bit of open water, not more than 7 or 8 yards in diameter, in an ice-covered lake near Blacktail Deer Creek. Once they flew off but returned to the water after making a wide circle. They were restless and apparently dissatisfied with the size of the opening. When a coyote came trotting toward them on his way to some carrion they flew away while he was still about 70 yards from them, thus indicating their alertness and feeling of insecurity.

I do not doubt that a coyote would seize a duck if he had a chance, but it appears that this opportunity occurs so seldom that both the birds and the coyotes usually ignore each other, especially when the birds have the advantage, as they generally do. O. J. Murie in his notes for January 25, 1939, in Jackson, Wyo., writes:

Up in the swamp today, below the old Peterson Place, two coyotes were feeding on the last remains of a dead elk. About 100 yards away or a little more, three trumpeter swans were feeding and preening contentedly, while in the stream nearby, probably 10 or 15 yards away, a duck was feeding.

Such observations are quite typical of the relationship existing between ducks and coyotes.

CANADA GOOSE

The Canada goose (Branta canadensis canadensis) is generally distributed over the park in all favorable habitats in summer, and in winter a number of them are found on the open waters, especially on the Madison, Firehole, and Yellowstone Rivers. When not feeding in the water the geese spend much time grazing on green vegetation on land, at times a mile or more from the water. In late summer, quantities of grasshoppers were eaten at some of the meadows.

Although adult geese are unusually alert it does not seem unlikely that a goose is occasionally captured by coyotes. In winter some remains of geese that may have been killed by coyotes have been found by rangers along streams. However, from the information available, the total winter and summer predation on geese is not extensive. In the spring of 1937 I found remains of four geese along the Lamar, Firehole, and Madison Rivers only by covering long stretches of these streams.

There is always the possibility that some of the geese eaten by coyotes represent carrion. The winter keeper at Canyon said that a goose unable to fly had been seen two successive winters on the Yellowstone River. Such a goose is at a disadvantage and might sooner or later be picked up by a coyote. Rangers E. E. Peterson and Guy McCarty (Yellowstone Nature Notes, April 1930, p. 20) report an incident in which two geese crashed into the steel cable across the Yellowstone River one-half mile above Chittenden Bridge. One goose received a broken wing and the other was swept over the falls.

Goose remains were identified in only 12 droppings. As seven of these droppings were found near a dead goose along the Lamar River and in a hay stack only a short distance away, they apparently represented the same bird.

When a coyote feeds near a group of geese one or more of the birds generally keeps a close watch. Usually the coyote pays little or no attention to the geese even though it may be within 40 or 50 yards of them.

Geese in the park nest in various situations. Two nests were found on top of hay stacks at the Buffalo Ranch. In passing one of these a goose on the nest lowered its head and neck against the hay but at the same time kept a close watch of me. Many nests are built on hummocks and islands in the water and others on the mainland. There was not time to make a detailed survey of the extent of coyote predation on goose nests and young, but information indicates that many geese were being successfully raised in the park.

Figure 53— Canada geese spend much time on land but their watchfulness makes it
hardly worthwhile for coyotes to attempt to stalk them.
Elk Park, April 12, 1938.

On July 11, 1937, on the Lamar River near the Buffalo Ranch where coyotes are plentiful five families of geese were seen and a few days earlier another family was recognized as different from the others because of the large size of the young. Other families noted in 1937: June 11, Oxbow Lake, (2); Floating Island Lake, (1); June 15, Madison River, (1), Nymph Lake, (2); June 16, Yellowstone River, (2); June 17, Buck Lake, (1); June 19, Pelican Creek, (1). The 16 families ranged in size from one to six, and made a total of 49 young. There was no systematic effort to make a large count of geese. They were only tabulated as I happened to note them. Since geese can hide well on shore it is probable that some were overlooked in the territory covered. The three young at Floating Island Lake were seen there until September 30. Late in September the family was flying about but often returned to the home lake.

During the summer of 1938 I spent relatively little time in the park but noted several geese with young as follows: June 4, at a shallow pond near Trumpeter Lake, two families of two and four young; June 8, Floating Island Lake, one family of seven; July 12, on Nymph Lake, one family with one young and two with four in each; July 13, Oxbow Lake, a family with six young. On August 13 there were still seven young at Floating Island Lake and five were seen at Oxbow Lake.

The general abundance of geese and the prevalence of young indicates that geese are doing exceptionally well in Yellowstone. The few goose remains in the droppings show that these birds seldom fall prey to coyotes.

TRUMPETER SWAN

The relationship of coyotes to trumpeter swans (Cygnus buccinator) is of special importance because of the relatively small numbers of these swans still surviving. In the United States their breeding range is restricted to the Yellowstone National Park, Jackson Hole, and Red Rock Lakes regions. In Canada they are more widely distributed and less rare.

Status of swan in Yellowstone National Park.—The best information available on the status of the swan in Yellowstone National Park, taken from the 1937 and 1938 reports, is included in the following table:

Recent counts have been more thorough than the earlier ones, but even these last census figures may be incomplete.

In 1937, 40 adult Yellowstone swans produced 29 cygnets, while at Red Rock Lakes 38 adult swans produced 51 cygnets. This apparently lower productivity in Yellowstone is perhaps due to the presence of a larger number of nonbreeding birds in the park, birds probably too young to breed, or unmated for some other reason; also the Red Rock Lakes Refuge contains a larger area of suitable nesting habitat than does the park.

The swans begin nesting as soon as the ice goes out in late April and early May. Hatched in June, between 30 and 35 days after the eggs are laid, the cygnets usually do not begin to fly until late September.

In 1937 there were 7 pairs of swans which produced 29 cygnets. So far as known all but one cygnet of those that hatched survived through the summer.

The small increase in 1938 was due mainly to the small number of swans nesting and to small broods hatched. Three adult females found dead in early spring were probably potential breeding birds. Oberhansley and Barrows in their 1938 Yellowstone trumpeter swan studies (submitted in 1939) record 12 eggs that failed to hatch due to sterility, human disturbance, and unknown causes. The four cygnets surviving when the count was made in August were produced by four pairs. A fifth pair abandoned its nest apparently due to human intrusion.

At Beach Springs two unhatched eggs were found in the nest after the swans had left. At Swan Lake four of the six eggs laid failed to hatch. The eggs at Swan Lake remained in the nest for some time after the birds had left before they were collected and during this time, a period of 8 days, had not been molested.

At some of the lakes where swans have been raised, coyotes are concentrated. At Trumpeter Lake where seven cygnets were raised in 1936 and again in 1937, coyotes and coyote signs were frequently noted at the lake. Nineteen of thirty coyote droppings found at the lake contained only grasshoppers, and the others, except for one, contained elk, pocket gopher, and field mouse. The only evidence of waterfowl predation consisted of some remnants of a green-winged teal found on the bank and in one dropping. The swans here spent considerable time resting on the banks and occasionally walked with their brood a couple of hundred yards to an adjoining lake.

Usually the nests are located on islands in the water but occasionally they are on the shore. In 1937 the nest at Beach Springs and the one at Geode Lake were on shore. In the vicinity of these lakes coyotes are common. Since the swan on a nest is very conspicuous, the coyotes frequently must have seen these swans on the nests. While one bird is on the nest the mate is much of the time nearby, often only a few feet away. It is possible that two swans are a little more than a coyote cares to tackle, especially when mice and pocket gophers are available in abundance for food.

The swan may also enjoy some measure of safety from the watchfulness of its associates. At Trumpeter Lake, and some of the other lakes, many blackbirds, mainly red-winged and yellow-headed, nest in some numbers. The presence of many of these birds on the margins of the lakes makes it unlikely that a coyote could remain long in the vicinity without attracting their attention and their alarm notes would warn the swans. Other birds, such as ducks and grebes would also help keep the lake inhabitants in formed of the approach of a coyote. The swans, when feeding, are often followed by grebes, ducks, and geese who benefit from the stirring up the swan gives the under-water vegetation.

The swans themselves are alert but do not show much fear of other animals. On May 28, 1938, Frank Oberhansley and I watched two adult swans at Geode Lake from 4:05 p. m. to 5 p. m. They were idling about 4 feet apart on the low shore about 7 feet from the water. Their necks rested gracefully over their backs and their bills were pushed under the feathers inside the wings. The eyes of one of the birds seemed completely covered by the feathers most of the time, but the other had its eyes exposed. Once or twice during the first half hour that we watched they stretched their necks to look around but for more than 10 minutes at a time they seemed to sleep soundly. At 4:45 the swan whose eyes showed stretched its neck upward and a moment later the other also lifted its head into the air. They both looked inland; neither stood up. Presently a black bear passed below us about 25 feet from the swans. The bear did not pay any attention to the birds; it may not have seen them. While the bear was passing, the swans commenced to preen themselves and presently tucked their heads away for another nap. Two geese grazed on grass near them, always alert, and surely useful in announcing the approach of strangers.

On June 5 Oberhansley saw the two swans at Geode Lake resting on the shore where we had seen them on May 28. While he watched, a coyote passed near them, where we had seen the bear pass. The swans paid very little attention to the coyote, who in turn paid little attention to them. In trotting past it barely glanced in their direction.

In the fall of 1938 the Bureau of Biological Survey transported four swan cygnets from the Red Rock Lakes Migratory Waterfowl Refuge to some warm springs on the Elk Refuge in Jackson Hole. One of the birds disappeared soon after being released and no further trace of it was found. It may have flown away. The other three swans survived the winter even though it appeared in March that food in the water was becoming scarce. It is interesting to find these young birds, transported to a new environment, surviving in spite of the fact that coyotes were common. Coyotes were frequently seen in the vicinity of the area occupied by the birds.

A number of observations indicate that factors not at all related to predation tend to lower the swan population. In the spring of 1926 a dead mature swan (manuscript of Trumpeter Swan Report, Yellowstone National Park, Summer 1936) was found at Swan Lake, but the cause of death was not determined. The carcass was intact, so the bird seemed to have died from disease. Another dead swan was found on Daly Lake, between Livingston and Gardiner, early in the spring. The cause of death was unknown.

During the winter of 1935—36 Ranger Frank Anderson saw a dead swan floating down the Yellowstone River. A few years ago, O. J. Murie found two dead swans in a pond near Moran, Wyo., in early spring, which had died of disease or starvation.

During the spring of 1938 three dead swans were found in Yellowstone Park. All were adult females, probably birds which had been regular breeders in the park. The circumstances surrounding the deaths of these swans are as follows:

On April 12, Tom Phillips, a workman at the Buffalo Ranch, found two coyotes feeding on an adult swan on Slough Creek. Part of the back had been eaten and the neck was severed. The bird seemed to be in fair condition. It weighed 18-1/2 pounds, and I estimated that 1-1/2 pounds had been eaten. The intestines, proventriculus, and gizzard were empty and only a small quantity of sand was found in the latter. It was thought by Mr. Phillips that this swan was killed by coyotes, but considering the lack of food in the digestive tract it is more likely that the bird was not in normal condition and may have died before the coyotes found it. Archie Hull, in charge of Red Rock Lakes Migratory Waterfowl Refuge, told me that he had lost several swans from lead poisoning, caused by lead shot in waters frequented by duck hunters, and that he had found birds dying from this cause before losing their fat. Although no shot was present in the gizzard of the swan under discussion, there have been cases in which all the lead had been absorbed before death ensued.

On May 5 Ranger Walter Gammill found a dead swan on the shore of a shallow pond a few hundred yards east of Trumpeter Lake. I had seen the swan on this pond on April 25 and 28 and again on May 1 when it was resting on the shore 5 or 10 yards from the water. The shore of the pond where the swan was found is low and level, offering no cover for a stalking coyote. The head and one leg was missing and a little of one breast had been eaten. This was an adult female. The proventriculus was empty and the gizzard contained only about a level teaspoonful of grit. The intestines were also almost empty. The bird was so emaciated that there was no fat on the skin. The bird had unquestionably been sick.

On May 10 the linemen in the park reported that a dead swan was lying in Trumpeter Lake. Assistant Park Naturalist Oberhansley retrieved the swan and when we examined it we found no physical injury except a small festered spot on the back. This swan was also emaciated, weighing only 14 pounds, 14 ounces. The proventriculus was swollen and congested with green food. A number of much worn lead shot were found in the gizzard. The condition of the proventriculus and the presence of lead shot indicates that the bird, an adult female, died from lead poisoning.

On April 28 and May 1,1938, a pair of swans were seen building a nest on Trumpeter Lake where the nest had been located the previous year. A mound of dead reeds was built about a foot above the water. After May 1, although the swans remained at the lake during the summer, no further nest building was noted. Shillinger and Cottam, (1937, p. 400) suggest that lead poisoning might upset the breeding activities of waterfowl. They write:

Even though a sublethal dose of lead is taken, experimental evidence indicates that the poison so upsets the normal physiological processes that interference with reproduction may result. It is well known that lead acts as an ahortifacient in mammalian females and there is evidence that leads us to believe that it may induce sterility in birds.

There is a possibility, in view of the death of at least one swan and possibly two others from lead poisoning, in Yellowstone, that a sublethal dose of lead may also have interfered with the breeding of the pair at Trumpeter Lake.

The present status of the trumpeter swan is being given much attention. The 1937 census in the Yellowstone and Red Rock Lakes areas revealed 168 birds, and in 1938 there were 151. How many additional birds this region will support is unknown but it is not unlikely that the swan population is approaching the saturation point in this restricted area. Two limiting controls inherent in the region may be lack of nesting sites and a shortage of winter food. The nesting waters used by swans must have suitable nesting sites and also an adequate proper food supply. No study has been made of the wintering areas so far as I know, but it would seem that in the wintering waters there is a definite limit to the swan food supply. These same waters are occupied by numerous ducks and geese in winter, probably congregating there to the carrying capacity of available food supply.

J. A. Munro, Chief Federal Migratory Bird Officer for British Columbia, reports (Pough, 1939) on the winter food of the estimated 500 trumpeter swans in British Columbia:

The number of cygnets usually equals or exceeds the number of adults and from this it can he inferred that the summer loss through natural enemies is not large. Nevertheless there is, periodically, a heavy loss from starvation brought about by adverse weather conditions.

Probably the most serious direct mortality factor affecting the swans today is lead poisoning, to which these birds are very susceptible. Some of the victims have been found but no doubt many others have not been observed. Lead poisoning may operate not only in reducing the swans on the present range but also to prevent a spread into other areas.

Munro is quoted as follows concerning losses from lead poisoning:

At that time (1918) definite information was available regarding the wintering ground of one band which at its maximum contained 22 birds. The area involved was established as a Federal Bird Sanctuary with a warden service which is still maintained. Subsequently the greater part of this particular band died from lead poisoning; the number returning grew smaller each year and the flock finally disappeared.

These birds were probably so unfortunate as to spend part of their time on lakes whose bottoms contained much lead shot.

Another factor detrimental to the spread of swans is the accidental shooting of the birds when they get out into unprotected waters.

It was rather unexpected to find that the coyote in Yellowstone exerts no appreciable pressure on the trumpeter swan population. However the long necks of the swans give them an advantage in seeing any intruders. Furthermore, the swan is no doubt an adversary to be respected, for it is known that a swan can administer a powerful blow with its wings. At any rate, whatever may be the deterrents, the coyotes can find plenty of food during the summer without taking risks of being bruised. The data available at the present time indicate that the coyote does not represent an important mortality factor for the trumpeter swan.

In Yellowstone National Park and in all nesting areas precautions should be taken to prevent the birds from being molested during the summer season when the birds are nesting and raising their young. Roads, trails, fishermen, and other disturbing factors should not be permitted where swans are nesting and raising their families. Disturbance, at least in one known case, when the eggs had been laid, resulted in failure of eggs to hatch.

To insure the survival of the trumpeter swan in the United States a wider distribution should be encouraged. A step in this direction was taken by the Biological Survey when they moved four young swans into southern Jackson Hole, where three of them remained and wintered successfully. Probably more extended efforts of this kind would be desirable.

RICHARDSON GROUSE

Remains of Richardson grouse (Dendragapus obscurus richardsoni) were found in five droppings; grouse, either Richardson or ruffed grouse, in five droppings. One of the grouse was a chick.

The blue grouse population seems to fluctuate very little in the Yellowstone region. This grouse is not abundant, but still is frequently found, especially on ridges and high slopes. It is commonly found at lower elevations in summer, but generally moves to higher elevations in winter. C. H. Merriam (Hayden, 1873), who made a trip in 1872 through Yellowstone and Jackson Hole, states: "The species was not abundant, being met with chiefly in the Teton Mountains."

During the middle of May 1937 a number of males assembled each evening on a sagebrush slope near Antelope Creek to strut and hoot. On May 18 I saw seven or eight males assembled and heard others close by. A fresh coyote dropping picked up on the area contained the foot of a blue grouse. There were four other fresh coyote droppings on the road nearby containing mainly elk hair. The assemblage of droppings made it appear that the coyotes had been attracted to prey on the grouse. On May 23 a ranger informed me that he and another ranger had found, in the fenced buffalo pasture below the place where the grouse were strutting, a blue grouse with the head eaten off and in another spot a mass of feathers. This seemed to indicate that the coyotes were getting several grouse. It occurred to me that these birds may have been found along the buffalo pasture fence after being killed by flying into it, so I walked along the entire fence. I found the body of the grouse mentioned above, but on searching found its head 7 feet on the other side of the fence. It had been severed when the grouse hit the fence. Another grouse had suffered a deep cut at the base of the skull where it had struck the wire. Remains of three blue grouse and four ruffed grouse were found along the fence, five of the kills being recent, and all had been eaten except two ruffed grouse. Obviously all of these were carrion, resulting from the presence of the wire fence. Two of the blue grouse remains were about 200 yards directly below the spot where the grouse had assembled each evening and where I had found grouse remains in a coyote dropping. Since these blue grouse in the buffalo pasture had been eaten recently, there was some probability that they were the source of the grouse remains in the dropping found in the road. Nevertheless, it still seemed that the drumming grouse must have attracted the coyotes to the spot, because of the number of fresh droppings there. However, the true explanation of the frequenting of the area by coyotes came to me as I climbed the slope to the strutting area. Upon examining a spot about 75 yards below the grouse rendezvous, from which a raven was flushed, I found several neck vertebrae of an elk and some bloody elk hair. Apparently an elk carcass rather than the blue grouse had been the attraction. The incident is here related to show how easy it is to draw incorrect conclusions from field observations.

On June 10 near Trumpeter Lake some blue grouse feathers were found on a dirt mound at the entrance of a burrow. Upon examining the vicinity, the main mass of feathers was found 5 yards from a spot below some telephone wires. This grouse probably had met death by flying into them.

On November 6, 1937, I located remains of a blue grouse which had recently flown into the buffalo pasture fence and on May 27, 1938, remains of another were found along the fence. It is likely that grouse, because of their precipitous rapid flight, are killed more frequently by flying into wires and other objects than are other birds.

No evidence was secured to indicate that coyotes were preying extensively on this species.

Figure 54— A blue grouse in early spring. There are occasional records of grouse, killed by hitting wires,
forming carrion for coyotes.
Teton National Forest, April 1936.

RUFFED GROUSE

Ruffed grouse (Bonasa umbellus umbelloides) were identified in two droppings. In addition, the contents of any of five droppings which were identified as "grouse," may have belonged to this species. It is my impression that the ruffed grouse is slightly more plentiful in Yellowstone than is the blue grouse. The population seems to remain rather stable, and marked cycles of abundance and scarcity apparently do not occur regularly. C. H. Merriam (1873) in 1872 found that the ruffed grouse "was not an abundant species though it was found throughout the pine forests from Teton Canyon to the Yellowstone." This agrees with my observations during the past 10 years in which I have been familiar with the Yellowstone-Jackson Hole area. Coyote depredations on ruffed grouse do not appear to be serious.

OTHER BIRD REMAINS

Remains which could be classified only as "bird" were found in 62 droppings. These included 55 "small birds," 18 "large birds," 5 immature sparrows, 1 sparrow, 2 Steller's (black-headed) jays, 2 warblers, 1 spotted sandpiper, 1 short-eared owl, 2 grebes, 10 large bird eggs, 7 small bird eggs, 3 domestic chickens (refuse), and 13 chicken egg shells (refuse). The domestic chicken and chicken egg shell were secured from garbage.

The jay was probably captured at a carcass. The grebe, eaten in the fall, probably was carrion since these birds would not otherwise be available to coyotes. At that time, otters in Yellowstone Lake were feeding considerably on grebes which they no doubt can capture in the water. The coyote may possibly have eaten a grebe killed by an otter.

Potential bird carrion aside from duck remains was represented by carcasses of two robins, one hermit thrush, and a magpie, whose carcasses were found intact, and an adult marsh hawk unable to fly. On September 22, 1938, a long-billed dowitcher was picked up at Yellowstone Lake with a wounded wing. Feather remains of two red-tailed hawks, one short-eared owl, one meadow lark, one bluebird, one magpie, and one Steller's jay, were noted, besides those of ducks, grouse, and other kinds mentioned elsewhere.

There is always some question as to how near a coyote must approach a bird on a nest before it scents the nest. On two occasions I found unmolested nests of the white-crowned sparrow about a foot above the ground in the brush bordering the trail over which coyotes were traveling regularly. On June 14 I found the nest of a spotted sandpiper 15 feet from the Lamar River. The bird tried to entice me away by acting wounded. Seven feet from the nest were fresh tracks of a coyote which had passed without noticing it. Four nests with eggs and two pairs with young were noted in June 1937. All of these were found along the streams much frequented by coyotes. The spotted sandpiper is common in the park.

On several occasions, coyotes were observed jumping after bluebirds and sparrows, but this apparently was done mainly in play. At times they may be successful in catching the birds.

At carrion it seems that the magpies would be vulnerable to coyote attack, for frequently upward of a dozen magpies were seen hopping over a dead elk or deer on which coyotes were feeding, completely ignored by the latter. Some have been seen feeding less than 2 feet away from the coyote's head. At times the coyotes chase the birds, but it seems this is done mainly to drive them away and not to catch them. There seems to be a sort of instinctive neutrality between coyotes and magpies (also magpies and hawks) at carrion. However, the magpies are always alert at a carcass and ready to avoid being seized. The coyote may have found by experience that it does not pay to try to catch these birds.

O. J. Murie (1935, p. 19) found that coyotes had frequently visited the base of a high cliff on which a colony of cliff swallows were nesting. On July 22, 1937, in Hayden Valley a young dead cliff swallow was found beneath a cluster of their nests.

The number of all bird items including ducks, geese, and grouse, and the egg remains, occurring in 5,086 scats is 273 or about 5 percent. Birds are usually taken accidentally.