great snowy owl had killed an ermine and T. McIlwraith shot a bald
eagle at Hamilton Bay which had the bleached skull of a weasel
(probably of this species) clinging to the throat (Seton, 1929
(2):603).
A. B. Howell (1943:98) likens mustelid mammals to domestic cats in
their manner of crossing roads and thinks that mustelids loiter at the
side of the road until the stimulus of the approaching car causes them
to make a dash whereupon they are caught by the wheels and killed.
Three of four weasels seen to cross the road were killed, one even
having apparently crossed the road before turning back and being killed
under the car. One weasel killed was _Mustela erminea cicognanii_.
Dalquest (1948:190) in writing of this species in the state of
Washington, says "I have seen only one abroad in the daytime. It dashed
from a roadside thicket . . . and was crushed beneath the wheels of a
car."
Food
The killing of prey is described by Hamilton (1933:332) as follows: "A
rapid dash, and the bird or mouse is grabbed over the back of the
skull, the fore legs encircle the animal as though hugging it, and the
hind legs are brought up to scratch wildly at the captive. . . . If
[the prey is] a large animal, as a rat, the weasel usually lies on its
side, while the diminishing struggles of the rodent continue, but if a
mouse or a small bird [is the object of attack], the weasel is apt to
crouch over its prey. Little time is lost over the first [mouse] . . .
if two mice are present [;] a strong bite through the brain case . . .
[is] sufficient. If only one animal is present, the weasel dawdles over
its kill some time after life has departed."
Hamilton's (1933:333) study of the contents of the digestive tracts of
bodies of ermines obtained from fur trappers and fur buyers in New York
enabled him to publish the following "Frequency Indices of Mammal
Genera in Fall and Winter Food of 191 Mustela cicognanii": _Microtus_,
35.7 per cent; mammals undetermined to genus but principally mice,
16.3; _Blarina_, 15.1; _Peromyscus_, 11.4; _Sylvilagus_, 9.0; _Sorex_,
4.9; _Rattus_, 4.4; _Tamias_, 3.6. Close correspondence is shown by the
following data of Aldous and Manweiler (1942) for the ermine from Lake
of the Woods, Minnesota: mice, 58.7 per cent by number and 54.5 by
volume; shrews 22.5 and 21.8 per cent; birds, 2.7 and 5.0 per cent. Of
the mice in stomachs, 40 per cent were microtines, 15 per cent were
_Peromyscus_ and 45 per cent were unidentified as to kind. Fragments of
a small fish were found in one stomach. Summed up, the dominant winter
foods were mice and shrews. Trapping of the mammal populations was done
to see what the available food was and it was found that the small
mammals were eaten in direct ratio to their relative abundance.
Snowshoe rabbits and red squirrels were not eaten. The Minnesotan data
were from 60 stomachs and 53 intestinal tracts recovered from 129
weasels trapped by use of scent (not bait) mostly from January 1 to
February 7, 1939, although a few were trapped in 1938. Analyses of
contents from stomachs gave approximately the same results as those
from intestines. In 1939 at Lake of the Woods, weasels were
concentrated where food was abundant but no such concentration was
noted in the following winter.
Big short-tailed shrew (_Blarina brevicauda_).--In New York State, the
ermine preys on _Blarina_ as shown by Hamilton's (1933:330) seeing one
being carried by a male ermine on May 6, 1931, and another being
carried by a female on May 13, 1932. The same author (1928:249) found
the remains of a _Blarina_ in a small female from Malone, New York.
Kirk (1921) observed, however, that the ermine (_M. e. cicognanii_)
avoided the shrew, _Blarina_, caught in a trap and that _Blarina_
avoided the weasel caught in a trap.
Chipmunk (genus _Tamias_).--Remains were found in a male ermine in New
York on May 14, 1932 (Hamilton, 1933:330), and Seton (1929 (2):602)
records a chipmunk at Lake Couchiching, Ontario, that was pursued into
the water by an ermine.
Deer mice (genus _Peromyscus_).--As shown by Hamilton (1933:33) and
Aldous and Manweiler (1942), _Peromyscus_ was second only to microtines
in numerical abundance among the food items of ermines in New York and
Minnesota. _Peromyscus_ and microtine rodents were brought to a den of
the diminutive _M. e. muricus_ in early August, in Fresno County,
California, according to Ingles (1942). He observed that an Alpine
chipmunk was active under and around the tree and that juncos reared
young 40 feet from the den but that the chipmunk and juncos were
unmolested by the ermines.
Lemming (genus _Lemmus_).--One was recovered from a female ermine (with
milk in her glands) at Laurier Pass, British Columbia (Sheldon,
1932:201).
Red-backed mouse (genus _Clethrionomys_).--Criddle and Criddle
(1925:146) record that on "May 31, 1921.--Saw a Bonaparte's weasel
capture a Red-backed Vole after a long hunt during which the pursuer
never once lost track of its victim."
Meadow mice (genus _Microtus_).--As shown by the data of Hamilton
(1933:333) and Aldous and Manweiler (1942) recorded above, _Microtus_
is the item of first importance in the diet of the ermine in New York
and Minnesota. Criddle and Criddle (1925:146) write concerning the
vicinity of Treesbank, Manitoba, that "October, 1918.--Following a
severe outbreak of mice in 1916-17, Bonaparte's weasel increased
enormously and very soon reduced the rodents to comparative rarity.
This resulted in a scarcity of food for the weasels, which in their
turn became greatly reduced in numbers."
Old World rat (_Rattus_).--Bishop (1923) found two headless rats near a
nest of this species in Albany, New York.
Pika (_Ochotona_).--Dixon (1931:72) at Milner Pass, Colorado, on July
20, 1931, saw an ermine, of the subspecies _muricus_, following a
three-fourths grown pika by scent and outrunning the pika. The pikas
worked a relay system and the weasel abandoned the trail when the
fourth pika became the object of the chase.
Cottontail (genus _Sylvilagus_).--Hamilton (1933:33), as noted above,
found remains of cottontail in the digestive tracts of ermine that had
been trapped for fur in winter. Possibly these remains were bait that
had been placed at traps.
Snowshoe rabbit (_Lepus americanus_).--Morse (1939:210) in a study of
predation on hares and grouse in the period of notable decimation of
these two game species in 1935-1936 in the Cloquet Valley State Forest,
in St. Louis County, Minnesota, found that "weasel predation on hares
appeared to be of very low incidence or altogether lacking."
Wild birds (Class Aves).--Aldous and Manweiler (1942), as noted above,
found that the remains of birds constituted five per cent by volume of
the food of the ermine in winter in Minnesota.
Chicken (genus _Gallus_).--Criddle and Criddle (1925:145), who
published relatively extensive data on the three species of weasels of
Manitoba, write that: "We have no record of Bonaparte's weasel killing
poultry, and we doubt whether it ever does so." However, Soper
(1919:46) investigated the excited cackling of a hen brooding chicks at
night and found a solitary ermine that had killed three chicks and that
had the remainder under very active scrutiny.
Leopard frog (_Rana pipiens_).--One frog was found in a male ermine on
November 20, 1931, in New York by Hamilton (1933:300).
Fish (Class Pisces).--Aldous and Manweiler (1942) found fragments of a
small fish in one of 60 stomachs of ermine from Minnesota.
Earthworm (Phylum Annelida).--Osgood (1936:64), presumably at Rutland,
Vermont, observed a pair of weasels from 2:15 P.M. to 5:00 P.M., in a
barn and saw the female in that time make many trips for food for her
young. Only earthworms were brought. Fifty traps in an adjacent, swampy
field caught only one bull frog and no mice indicating that mice had
been eliminated from the foraging territory of the ermine.
In handling food, Dice (1921:22) noted that the Alaskan ermine did not
use the feet but only the mouth.
Reproduction
Litters of 4, 4, 7, 7, and 8, yielding an average of 6 young per litter
have been recorded from the northeastern United States by Hamilton
(1933:327). He (_op. cit._:321-325) described animals one day old from
New York State as being flesh-colored, having the long neck of the
adult and a fine growth of white hair two millimeters in length, on
the dorsal surface of the neck, that foreshadows the mane or pompadour
that is prominent from the 14th to the 21st day of life. Six animals,
when one day old averaged 1.7 grams in weight, which was three per cent
of the weight of an adult female and one and one half per cent of the
weight of an adult male. At two weeks of age the heavy brown mane stood
out in marked contrast to the rest of the scantily, white-furred
animal. The eyes opened on the thirty-fifth day of life.
[Illustration: FIG. 24. _Mustela erminea richardsonii_, adult female,
Catalogue Number 14866, U. S. Nat. Mus., Fort Chimo, Ungava. × 1/2.
Ventral view of body of a pregnant female to show details of mastology.
Note the five pairs of mammae characteristic of weasels, and the uneven
arrangement of mammae of the two sides which is also common among
weasels.]
[Illustration: FIG. 25. Map showing geographic ranges of the subspecies
of _Mustela erminea_ in the New World.]
For rearing their young, ermines live in burrows. Bishop (1923), in
Albany, New York, found a burrow occupied by four young and a pair of
adults. The burrow had many galleries and contained a nest constructed
of rat fur, fine grass and fragments of leaves. At Woods Lake, Fresno
County, California, in early August, Ingles observed (1942) some young
and at least one adult at their den which was in a burrow beneath a
hollow tree. The ermines used the hollow root and the hollow tree as
well as the burrow beneath. Seton (1929 (2):591) quotes S. Eldon
Percival, of Barretts Rapids, Ontario, as finding the living quarters
of an ermine in unthreshed grain stacked in a barn and says (_op.
cit._:590) that John Burroughs dug out a nest, composed of leaves and
the fur of mice and moles, two or three handfuls in bulk, from a cavity
the size of a hat, arched over with a fine network of tree roots.
Four instances in which the male as well as the female was present at a
den containing young are cited by Hamilton (1933:328) and he gives some
evidence, although not at all conclusive, that "adults customarily
pair, or at least run together, at times other than the breeding
season." No other writers remark on this matter. I doubt that adult
ermines are associated in pairs for most of the year but such may be
the case.
=Mustela erminea arctica= (Merriam)
Ermine
Plates 2, 3, 4, 9, 10, 11 and 41
_Putorius arcticus_ Merriam, N. Amer. Fauna, 11:15, pl. 2, figs. 1,
1a, and pl. 5, figs. 6, 6a, June 30, 1896.
_Putorius_ (_Gale_) _erminea_, Coues, Fur-bearing animals, p. 109,
1877 (part).
_Putorius richardsonii_, Bangs, Proc. Biol. Soc. Washington, 10:16,
pl. 1, figs. 3, 3a, pl. 2, figs. 3, 3a, and pl. 3, figs. 6, 6a,
February 25, 1896 (part).
_Putorius cicognanii alascensis_, Osgood, N. Amer. Fauna, 19:43,
October 6, 1900.
_Putorius kadiacensis_, Osgood, N. Amer. Fauna, 21:69, September
26, 1901.
_Putorius audax_ Barrett-Hamilton, Ann. and Mag. Nat. Hist.,
13(ser. 7):392, May, 1904, type from Discovery Bay, Ellesmere
Island.
_Putorius alascensis_, Heller, Univ. California Publ. Zoöl., 5:345,
March 5, 1910.
_Mustela arctica arctica_, Miller, U. S. Nat. Mus. Bull., 79:97,
December 31, 1912; Dice, Journ. Mamm., 2:22, February 10, 1921.
_Mustela arctica_, Hall, Univ. California Publ. Zoöl., 30:420,
March 19, 1929.
_Mustela erminea arctica_, Ognev, The mammals of U.S.S.R. and
adjacent countries, 3:31, 1935; Hall, Proc. California Acad. Sci,
23:559, August 22, 1944; Hall, Journ. Mamm., 26:179, July 19,
1945.
_Type._--Male, adult, skull and skin; no. 14062/23010, U. S. Nat.
Mus.; Point Barrow, Alaska; July 16, 1883; obtained by John
Murdock, original no. 1672.
The skull has a fracture, on the dorsal surface, extending from
the anterior nares to the interorbital constriction and another
fracture on the left margin of the nasal bone. The middle of the
left zygomatic arch is broken away. Otherwise the skull is
complete. Right incisor one, above and below, are missing.
Otherwise the teeth are present and entire. The skin is in the
brown summer pelage, well made, in a good state of preservation,
and shows no obvious signs of fading.
_Range._--Arctic regions of Alaska and western Canada from the
Pacific Ocean to Smith Sound; from the northern limit of land
south approximately to a line from Skagway through Ft. Goodhope,
north shore of Great Bear Lake, south shore of Clinton Colden
Lake, north shore of Baker Lake, west end of Wagner Bay to south
end of Committee Bay. See figure 25 on page 95.
_Characters for ready recognition._--Differs from _M. e. polaris_
in darker upper parts (Raw Umber rather than Buckthorn Brown) and
less intensely colored underparts that are Sulphur Yellow,
Colonial Buff or Primrose Yellow rather than Buff Yellow; from _M.
e. semplei_, in males, in that hind foot more than 44 and basilar
length more than 41 and in that females average larger, the skulls
of females being only about 11 per cent heavier; from _M. e.
kadiacensis_ in hind foot more than 33 in females, zygomatic
breadth amounting to more, rather than less, than distance between
last upper molar and jugular foramen irrespective of sex; from _M.
e. richardsonii_, _alascensis_, _salva_ and _initis_, both sexes
so far as known, by proximal two-thirds of under side of tail
colored same as underparts rather than same as upper parts, and by
zygomatic breadth amounting to more, rather than less, than
distance between last upper molar and jugular foramen.
_Description.--Size._--Male: Six adults from Tanana, Alaska, yield
average and extreme measurements as follows: Total length, 336
(310-350); length of tail, 93 (84-105); length of hind foot, 49
(45-51).
Female: Five adults, one each from Alatna River, mountains near
Eagle, Kamarkak in Alaska, Arctic Red River and Baillie Island in
Canada, yield average and extreme measurements as follows: Total
length, 285 (272-304); length of tail, 77 (68-95); length of hind
foot, 39 (34-43).
Weight of 5 subadult males from Tanana is 206 (163-248) grams;
adults would be heavier.
_Color._--Winter pelage all white except tip of tail. Summer
pelage with upper parts uniform in color and Raw Umber or darker
(16_n_) of Ridgway and about tones 2 to 3 of Chocolate of Oberthür
and Dauthenay, pl. 343, but in autumn some specimens have more
light red than tones 2 or 3. Underparts Sulphur Yellow, Colonial
Buff, or Primrose Yellow, often white on chin and insides of
forelegs; color of underparts extends narrowly over upper lips,
distally on posterior sides of forelegs onto antipalmar surface of
forefeet, onto proximal two-thirds or three-fourths of underside
of tail as length of tail is measured along tail-vertebrae, on
medial sides of hind legs to a point between knee and ankle but
reappears on antiplantar faces of toes and in some individuals is
narrowly continuous onto toes; rim of ear in some specimens with
short, white or pale hairs giving ears distinct whitish border;
least width of color of underparts averaging, in adult males from
Alaska, 65 (46-93) per cent of greatest width of color of upper
parts. Black tip of tail in 5 males in winter pelage from Tanana
averaging 84 (70-93) mm. which is 91 (75-107) per cent of length
of tail-vertebrae.
_Skull._--Male (based on 5 adult topotypes): See measurements and
plates 2-4. As described in _Mustela erminea richardsonii_ except
that: Weight, 3.5 (3.1-3.9) grams; basilar length 42.5
(41.8-43.3); length of tooth-rows more than length of tympanic
bulla; breadth of rostrum measured across lacrimal processes
averaging more than a third of basilar length; interorbital
breadth more than distance between glenoid fossa and posterior
border of external auditory meatus; zygomatic breadth more than
distance between last upper molar and jugular foramen.
Female (based on 2 adult topotypes and 2 adults and 4 subadults
from central Alaska): See measurements and plates 9-11. As
described in _Mustela erminea richardsonii_ except that: Weight,
1.5 (1.2-2.0) grams; basilar length, 35.7 (34.5-37.0); length of
tooth-rows more than length of tympanic bulla; breadth of rostrum
more than 30 per cent of basilar length; interorbital breadth more
than distance between glenoid fossa and posterior border of
external auditory meatus; zygomatic breadth more than distance
between last upper molar and jugular foramen (except in specimens
from Ellesmere Island where two distances are approximately
equal).
Cranial differences from _Mustela erminea kaneii_ (which occurs on the
Asiatic side of Bering Strait), in both males and females, are: larger
size relatively as well as actually, broader except in mastoidal region
where relatively (to basilar length) the width is less; preorbital part
of skull broader as well as longer.
From _kadiacensis_ differences in the skull of the male are: size less;
13 per cent heavier, relatively (to basilar length) narrower across
interorbital region and zygomatic arches; tympanic bullae relatively as
well as actually narrower. Judging by the single available adult female
of _kadiacensis_, the skull of female _arctica_ is larger in all parts
measured, a fourth heavier, has tympanic bullae of almost twice the
volume and the interorbital and preorbital regions, relative to the
braincase, are much reduced in whatever plane measured.
Differences from _richardsonii_, additional to those noted above in the
formal description of the skull, between the males, are: larger in all
parts measured except length of tympanic bulla which is about the same;
42 per cent heavier; relative to basilar length, skull broader with
preorbital part longer as well as broader; tympanic bullae more
inflated posteriorly. The same differences prevail between females
except that the skull is 36 per cent heavier and in _arctica_ the
length of the bulla is actually more (although relative to the basilar
length less) and its greater inflation posteriorly is hardly
perceptible. Differences from _alascensis_, additional to those
indicated in the formal descriptions of the skulls of the two, in
males, are: larger in every part measured; 95 per cent heavier;
relative to the basilar length, skull broader with preorbital part
longer as well as broader; measured at a point opposite the foramen
lacerum anterius, the width of the pterygoid space is more, rather than
less, than 40 per cent of its length. Excepting this difference in
width of interpterygoid space, the same differences prevail between
females, those of _arctica_ being 56 per cent heavier.
Comparison with _semplei_ is made in the account of that subspecies.
Skull indistinguishable from that of _polaris_.
_Remarks._--The person who studies specimens of this subspecies finds
labels inscribed with the names of naturalists well known to all
readers of literature on the Arctic. Sir John Franklin, R. McFarlane,
R. Kennicott, E. W. Nelson and R. M. Anderson are names which appear
commonly. Of Alaskan specimens prepared according to modern methods, a
large share was obtained by O. J. Murie and L. R. Dice.
The ermine was observed in the far north by early explorers and was
mentioned in the literature, almost always under the name then used for
the ermine of northern Europe and Asia. In 1896 Bangs misapplied to it
the name _richardsonii_ but Merriam in the same year corrected the
application of this name and proposed as new for this weasel the name
_arctica_, the name in use today. For almost 50 years after Merriam and
Bangs wrote about it, _arctica_ was treated, nominally at least, as a
species distinct from its other relatives in both the Old-and
New-World. The subspecific status of _arctica_ was emphasized in 1944
(555) by the present writer in reporting in detail upon the specimens,
of _Mustela erminea_, from Eastern Asia which were made available on
loan by Professor B. S. Vinogradov and the late Anatol I. Argyropulo of
the Leningrad Academy of Sciences. Specimens of _Mustela erminea
kaneii_ from the Asiatic side of Bering Strait and _Mustela erminea
arctica_ from the American side are distinguishable by slight cranial
characters but in coloration and external measurements I can detect no
differences. Merriam's (1896:16) mention of more golden-colored upper
parts and darker underparts in American specimens than in _erminea_ was
the result of his comparison of Alaskan and northern European
specimens. When Old World specimens from eastern Siberia, instead of
from Europe, are used the differences mentioned by Merriam do not
apply. Incidentally, many Siberian specimens have the white border, on
the ear, which Merriam (_loc. cit._) noted as a distinguishing feature
of _arctica_. When Merriam named _arctica_ he said (1896:15, 16)
"_Putorius arcticus_ . . . has heretofore been confounded with
_erminea_ or _richardsonii_. . . . It is interesting to find in this
country an Arctic circumpolar weasel which, though specifically
distinct, is strictly the American representative of the Old World
_erminea_." Bearing in mind that Merriam's concept of species and
subspecies (see Merriam, 1919:6) differed from that of nearly all
modern systematists it is clear from his statement quoted above that
he correctly understood the zoölogical relationship obtaining between
the ermines of the Old and New Worlds.
Ognev (1935:31) seems to have been the first to use the name
combination _Mustela erminea arctica_ for Alaskan specimens. Thereby he
expresses the view adopted here, namely that the American ermine is
subspecifically but not specifically distinct from the Old World
animal. Whether actual intergradation (crossbreeding) ever takes place
across the narrow Bering Strait I do not know. I doubt that
crossbreeding occurs but considering the Diomedes (islands), that might
serve as a half way stopping point, and remembering Mr. Charles
Brower's oral statement to me that he had seen tracks of ermine as far
as 10 miles from the northern shore of Alaska out on the ice, the
possibility must be granted of an occasional individual crossing from
one side to the other of Bering Strait on the ice in winter or of being
carried across when the ice broke up and drifted. If transfers of this
kind occurred often one would expect ermines to occur also on Saint
Lawrence Island where apparently they do not. The one skin (U. S. Nat.
Mus. no. 259046) seen as labeled from there, my friend, Otto William
Geist ascertained was imported as a skin with other furs from Siberia.