“Home is where the Hole is:”
Field Guide to Desert Holes
Pinau Merlin, Desert Naturalist
11 April 2010 @ Oasis Visitor Center, JTNP
74485 National Park Drive, Twentynine Palms, CA
Tread lightly: “Tiptoe through the crypto”
Why: Ubiquitous, serve as census data for area’s occupants.
Successful interpretation depends upon:
1) Definition of a hole or pivot or pallet
a. Hole goes somewhere
b. Pivot is an excavation
c. Pallet is a bedding site (e.g., Cottontails or Jackrabbits)
2) Size of hole (big is easier than smaller sized holes)
a. Usually exact size as that of the animal that lives there (because you don’t want something larger than you to occupy your own hole—lunch bait!)
b. Note true size--interior. Don’t count exterior because of possible soil erosion.
3) Declination Angle
4) Location of hole (in rocks, under cactus, etc.)
5) Tailings and other visual evidence such as multiple holes, tail drags, scrape marks, scent marks, and scat.
1) Tape measurer
4) Botanical Tweezers (or wooden coffee stick from In-n-Out Burger)
1) Nests, not holes. Look for spherical droppings in and around beds. Want to see all around. Good sense of smell. Very social, up to 25 congregate together at night during moonlit nights.
1) Coyote = tall (i.e., 12, 18, even 24 inches), round to oval, V-shaped debris tailings from between legs (like other canines). Dens for female and her puppies. May start with a pack rat hole and enlarge.
2) Badgers = tall (8 to 12 inches), half moon shape, and flat on bottom. Look at large debris fan, dirt everywhere. They can excavate faster than a man with a shovel. Looks for scat inside. Look for multiple holes. Some evidence of cooperative hunting—badgers, coyotes, and hawks.
3) Kit fox = taller (7 to 9 inches), smaller fan of dirt. About the size of a small house cat (4-6 pounds); looks larger because of legs. Scat around. Can dig 4-5 holes per month.
4) Desert tortoise = hole size varies, but a shallow hole matching the size of the shell. No mound. Also look for resting pallets. May use the rock shelter of a pack rat.
1) Pocket Gopher = Loose dirt on top, plug hole. Look at teeth: top can grow 11 inches long in a year while the bottom teeth can reach 14 inches of growth in a year. Create runs of 175-200 feet long. Females make latrines and pantries off to the side. After a rain, they open one end to allow air to try out. Plug hole again.
2) Burrowing (Borrowing!) owls = take ground squirrels hole. 90 degree turn off of the main tunnel. Can tolerate high levels of CO2. Collect scan. Babies can imitate the sound of a rattlesnake to ward off possible predators.
3) Kangaroo Rat = 6 inches, due to their standing up. Look in sand around creosote bush. Only one rodent per hole. They are not social (dear enemy relationship, “a situation in which a territorial animal responds more strongly to strangers than to its neighbors from adjacent territories”) with surrounding K-rats). If you thump outside the hole, they will thump back. Look for tail drags, but they can jump 9 feet. Multiple holes and runways on top.
4) Ground squirrels (round tailed or Antelope) = 2 ½-3 inches, slight angle down. Antelope ground squirrels in rocky soils. Look for multiple holes as well as divots, where they are looking for seeds or beetles; based on smell.
5) Pack Rats = **, **. Especially under cactus. Exits up to 18 feet away. House under cactus; in rocks, it is the den. Some sites are up to 51K years old. Sits and leaves droppings. Doesn’t tolerate extreme temperature ranges. Need moist and cactus garden is a good place. Females have nicer houses than males! May take 4-5 days to build house; collection area is 300 feet (100 yards) away.
6) Grasshopper mice. Holes go straight down; 90 degree turn. Howl to mark their territory. Pinacate (Eleodes genus; aka darkling or stinkbug or clown beetles). Aggressive predator on pocket mouse (which is smaller).
7) Lizard = ½ inch, half moon shape. Look for tail drags.
8) Tarantula = ***. Tropical spider likes monsoon season and humidity areas. Makes a J-shaped nest. Females have blond legs; males have dark legs.
1) Snakes are borrowers since they can’t excavate. They like to coil. Look for compression coils. In cool months, rocks or cliffs; and when it is mild out, open areas.
Field Notes from Cholla Garden, JTNP (10AM, partly cloudy and light breeze)
1) Senna, member of the bean family; see Senokot®, a laxative from this native plant)
2) Desert lavender
4) Desert Iguana
5) Quartz, on underside cyanobacteria
6) Gopher snake in cholla cactus (33 55.607N/115 55.672W) at 662M (WGS84)
8) Harvester ants, irregularly shaped holes. Seed hulls around the nest
9) Badger hole (33 55.676N/115 55.663W) at 663M (WGS84)
10) LUNCH: 12 Noon
11) Around 1PM, Kit fox hole under creosote bush, digging out another animal
12) Badger Hole
13) Male pack rat
14) Whiptail lizard (5 out of 10 species use parthenogenesis for reproduction
15) Rabbit scat in hole
16) Desert iguana tail on cholla cactus
Updated: 2 February 2011