Nature Notes

by Ralph R. Huestis

Special Number - 1951

Report On The Trapping And Marking Of Golden-Mantled Ground Squirrels At Crater Lake National Park, 1939
By Ralph R. Huestis

During the 1939 season 95 ground squirrels and 4 Allen chipmunks were taken in live traps in the rim area. Ninety squirrels were released (many squirrels were retaken and released several times) and 5 squirrels were kept captive for observation of their winter behavior. The data that might be expected to accrue from this procedure are:

The age distribution and sex ratio.
The population density in the area examined
The winter survival rate.
The foraging area of individual squirrels.
The special distribution of young of the year after they leave the mother's burrow.

Although the returns from this project are for the most part purely ecological there is the possibility of some practical utility should the squirrels, as has happened elsewhere, become infected with some communicable disease which would require their elimination from a give area. A proof that they are not migratory would greatly simplify the eliminative procedure.


Squirrels were taken in wire box traps obtained from the National Live Trap Co., Tomahawk, Wisconsin, and rewired to hold squirrels. They were marked by cutting hind toes for numbers 1 to 10 (toes cut in order from left to right), and by cutting front toes in order from left to right for 10 to 20, etc. Correspondence on the subject had elicited the information that ear tagging with metal tags is unsatisfactory because the tags come out. Cut toes were disinfected with 70% alcohol and did not appear to cause the squirrels any considerable inconvenience although some swelling of the cut digit could be observed and squirrels occasionally were noted to be favoring the foot in question for a day or so after the operation. However since many squirrels were seen foraging as usual within an hour after release and as no squirrel was retaken with an obviously infected foot the method seems to have been a good one.

The data are presented in tabular form.

No. Sex Trapping
Place Other Data
1.MJuly 21East side Information BuildingTail had been broken and healed again.

July 26East side Information Building

July 27Rim wall just east Information BuildingLarge male with rich color.

July 29Front platform Information BuildingFilling up burrow entrance between stones using excavated earth and rock on top.

August 15East side Information Building

August 16East side Information BuildingTaking dry grass down burrow under wood pile.

August 21Information Building platform

August 23Rim wall in front of Information Building
2.FJuly 25East side Information BuildingLactating. Scolded in trap, didn't struggle to get out.

July 27East side Information Building

August 1East side Information BuildingWith young squirrels.

August 2Rim wall in front of Information BuildingMooching peanuts.

August 11Front door Information BuildingFed.

August 15East side Information BuildingNow very fat, has lost end of tail.

August 15West side Information BuildingThis squirrel's burrow near #1 above on east side Information Building but with entrance on west side also. #1 has entrances on east and south.

August 15East side Information Building

August 17Front platform Information Building

August 21Rim wall front Information Building
3.FJuly 25Head of Sinnott rampLactating.
4.FJuly 27Rim wall 50 feet east Information BuildingLactating.
5.MJuly 27Shrub bed on Information Building walk southLarge male. Aggressive.

August 15Shrub bed southeast Information Building 150 feet
6.FJuly 271st bay in Rim wall east, Information BuildingLactating. Hole in ear.
7.MJuly 27Bed with crooked hemlock just southeast Information BuildingYoung (unweaned?)

August 24Bed west Information Building (1st west)
8.MJuly 27Bed southwest Information Building in line with Community HouseYoung.
9.MAugust 1East side Information BuildingSon of #2? Young. (with #10)

August 7East side Information BuildingAlone.

August 7West side Information Building

August 11East side Information Building
10.MAugust 1East side Information Building with #9Young of year.

August 15Bed with crooked hemlock southeast Information Building

August 242nd bed east Information Building
11.MAugust 1East side Information BuildingYoung. Brother of #9 and #10?
12.MAugust 2Bed 150 feet southeast Information BuildingYoung. Aggressive.
13.FAugust 2Bed 150 feet southeast Information BuildingSister of 12? Young.
14.MAugust 2Rim wall 50 feet east Information BuildingLarge male. Aggressive.
15.FAugust 2Bed with crooked hemlockLactating mother of 12, 13?
16.FAugust 2East side Information BuildingYoung and noisy Sister of 9, 10?

August 11Bed south Information Building at highwayNoisy.

August 15Bed south Information Building at highwayNoisy.

August 15Bed southwest Information Building in line with Community House
17.FAugust 2Bed with crooked hemlockLactating. Possible mother 12, 19?
18.MAugust 2East side Information BuildingLarge. Foraging in #l's territory

August 22Behind Sinnott sign at rampHusky. Not very fat.
19.MAugust 2Bed with crooked hemlockYoung. Brother of #12, 13?
20.FAugust 2Rim wall 100 feet east Information BuildingLarge. Not lactating. Sterile female?
21.MAugust 2Rim wall 100 feet west Information BuildingOld male.

August 11At Sinnott sign

August 22Rim wall 150 feet west Information Building
22.FAugust 2Behind Sinnott sign at rampYoung.

August 22Below wall along Sinnott ramp
23.FAugust 2Bed opposite drinking fountain head of Sinnott rampYoung.

August 7West side Information Building
24.MAugust 7Behind Sinnott signYoung.
25.MAugust 7West side Information BuildingYoung. Playing with other young.
26.MAugust 7East side Information BuildingYoung sibling #3 and 10?

August 11East side Information Building

August 15South Information Building in bed at road
27.MAugust 7Bed near fountainOld.

August 13Sinnott rampMooching.

August 22Sinnott ramp

August 23Rim wall at fountainMooching.
28.MAugust 7West side Information BuildingYoung, sibling of #25?

August 11South Information Building at road
29.MAugust 9Bed south Information Building at road
30.MAugust 9Bed south Information Building at roadYoung of year.
31.FAugust 9East side Information BuildingYearling or well advanced young of year. Had not been lactating.

August 22Sinnott rampMooching.
32.FAugust 11Behind Sinnott signHad been lactating. Adult.
33.FAugust 11Bed south Information Building at roadYoung.
34.MAugust 11Bed at drinking fountainYoung.

August 22Behind Sinnott signVery rich brown. Even "white" stripes are brown.

August 23Mooching at fountain
35.FAugust 11Bed south Information Building at roadYoung

August 24Rim wall 50 feet east Information Building
36.FAugust 11Bed at drinking fountainYoung.

August 22Behind Sinnott sign
37.FAugust 14Campground west Ranger's tentHad been lactating. Adult
38.FAugust 14Campground west small comfort station.Young
39.FAugust 14Campground south comfort station.Large. Had been lactating.

August 21At Ranger's tent
40.MAugust 14On stump near tentMedium sized. Yearling?
41.FAugust 15Bed east Information Building at RimOld and fat.
42.FAugust 15Bed southwest Information Building in line with Community HouseYoung and small.
43.----------------Missed number.
44.FAugust 22Below Sinnott signYoung and noisy. Red-toned pelage.

August 24Below Sinnott ramp near sign
45.MAugust 22Behind Sinnott signYoung.

September 7Behind Sinnott signWell grown at this date.
46.FAugust 22Sinnott ramp 1/2 way downYoung.

September 7Behind Sinnott sign
47.FAugust 22Below SinnottLarge and very fat.
48.MAugust 22At Sinnott Memorial (south wall)Adult with white belly spot.
49.MAugust 22Below ramp near MemorialWell grown young or yearling.
50.FAugust 22Below ramp near signYoung.
51.FAugust 22Tree just south Sinnott MemorialAdult.
52.FAugust 23Rim 30 feet east Information BuildingAdult.

August 24Rim 30 feet east Information Building
53.MAugust 22Bay just west LodgeVery target Released at Information Building.
54.FAugust 24Bay just west of LodgeVery large and fat.
55.FAugust 24Rim 300 feet east InformationRecently lactating Not fat. Pale pelage.
56.FAugust 24Rim 200 feet east Information BuildingYoung.
57.--August 24Rim 200 feet east Information BuildingEscaped. Was not sexed.
58.FAugust 24Bay no 1 west Information BuildingAdult. Wounds on chest and throat.

September 7Bay no 1 west Information BuildingThroat largely healed at this date.
59.MSeptember 6Boat LandingAdult. Bobtail.
60.FSeptember 3Boat LandingAdult

September 7Boat LandingAdult
61.FSeptember 6Boat LandingYoung.
62.FSeptember 6Boat LandingYoung

September 7Boat Landing
63.MSeptember 6Boat LandingAdult.
64.FSeptember 6Boat LandingAdult.
65.MSeptember 7Boat LandingYoung.
66.MSeptember 7Boat LandingAdult. Fat.
67.MSeptember 7Boat LandingAdult.
68.FSeptember 7Boat LandingAdult.
69.MSeptember 7Boat LandingAdult
70.FSeptember 7Boat LandingAdult Large
71.FSeptember 7Boat LandingAdult
72.MSeptember 7Behind Sinnott signYoung and rather small. White spot on ventral surface.
73.MSeptember 7Rim opposite Community HouseAdult.
74.MSeptember 7Rim opposite Community HouseAdult. Fat.
75.MSeptember 7Rim opposite Community House 50 feet west of 74Adult. Fat.
76.MSeptember 7Rim 300 feet east Information BuildingAdult seen at same place in half an hour.
77.FSeptember 7Bay just west of LodgeAdult.
78.FSeptember 7Bay just west of LodgeAdult.
79.MSeptember 72nd bay east Information BuildingYoung.
80.MSeptember 20Information Building back doorYoung and recently emerged.
81.MSeptember 22Head of Lake TrailLiberated at Information Building. Adult
82.MSeptember 22Head of Lake TrailLiberated at Information Building
83.FSeptember 22Head of Lake TrailTaken back to head of lake trail.
84.MSeptember 23Head of Lake TrailTaken back to head of lake trail.
85.MSeptember 23Head of Lake TrailLiberated at Information Building. Adult and fat.
86.FSeptember 23Head of Lake TrailTaken back to head of lake trail.
87.MSeptember 23Liberated at Information Building. Still there 2 hours later. Very large adult.
88.FSeptember 23Head of Lake TrailTaken back to head of lake trail.
89.FSeptember 23Head of Lake TrailTaken back to head of lake trail.
90.MSeptember 23Head of Lake TrailLiberated at Information Building. Adult. Fat.
91.MSeptember 23Head of Lake TrailLiberated at Information Building. Adult. Left ear notched.


Age and sex of trapped squirrels

femalesmales total numberper cent males
Adult squirrels2926 55 47
Young squirrels15 1934127
Total44 4589102

Reproduction in terms of the season as determined by lactation of adult females

July 21-August 7August 8-22 August 23-Sept. 8September 9-15
Lactating62  1-
Not lactating24 104

Number of times squirrels were retaken

12 345 678 910
Adults448 11

Young209 32


  1. Seventy-three squirrels were trapped between the Crater Wall Trail and the Lodge in a strip of territory about 150 feet broad. This represents a very dense population.

  2. Squirrels do not, in a season, move around much. They may repeatedly be taken in the same territory, rarely are found more than 100 feet away from it.

  3. The sexes are equal in number in the population; an excess of young males balances an excess of old females. This is the situation to be found in other rodent populations such as the deer mouse.

  4. All young squirrels taken in the vicinity of a mother's burrow were found to have traveled only a short distance away after weaning. This is a tentative inference and awaits further trapping data.

  5. Young are born during the months of June, July, and August and emerge from the mother's burrow during July, August, and September. At the Rim Area in 1939, the first newly emerged young were seen July 15th and the last September 20th. A lactating female was taken as late as August 24th. In 1938 the first young were noted in the Rim Area on July 31st and the last on September 15th. This seems to suggest that occasionally a mother may have a second brood.

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