WLF 315 Wildlife Ecology I Lab Fall 2012 Mammal Capture and Handling Lab Objectives: 1. Introduce field methods for capturing and marking mammals. 2. Gain experience in trapping, handling and marking fox squirrels. 3. Mark squirrels on campus to begin a mark-resight population estimation exercise. A brief natural history of fox squirrels: Five species of tree squirrels in the genus Sciurus inhabit North America. Fox squirrels (Sciurus niger) get their name from the fact that 1 of their 3 color phases resembles that of a red fox. The scientific name is derived from the second (dark) color phase; the species name, niger, means black in Latin. The third color phase is gray over yellow (Long 1995). Squirrels molt (change their coats) 2 times/year—once in spring and again in autumn. What color are the squirrels on campus? Do you see any color variation among individuals? Fox squirrels are the largest tree squirrel in North America. Body weights fluctuate seasonally and with variation in food supplies, however, females are often equal in weight or slightly heavier than males (Allen 1943). Weights range from about 500g to >1000g (Long 1995). Distribution of fox squirrels includes much of the United States east of the Rocky Mountains. Populations in western states have been introduced by humans. Fox squirrels use overlapping home ranges, however, females defend the area around their nest. Two different types of nests are used. Dreys are nests constructed of twigs and leaves, and are located in trees, usually >3 m above ground (Gurnell 1987). Dreys used in winter are enclosed and stout. They are usually lined with a soft material such as moss, fur, feathers, lichen, etc. The second type of squirrel nest, know as a den, is constructed in a cavity in a tree trunk. Some dens are naturally occurring, and others are holes that are excavated by the squirrels or by cavity-nesting birds. Squirrels are granivores, and eat a variety of seeds, nuts, tree fruits, fungi, and occasionally growing shoots or green plant material (Gurnell 1987). Like all rodents, fox squirrels have a pair of long incisors that continue to grow throughout the life of the animal. These teeth grow about 15 cm annually in squirrels (Long 1995). Fox squirrels scatterhoard (bury in the ground singly or in small groups) food items. This behavior contrasts that of red (Tamiasciurus hudsonicus) and pine (T. douglasii) squirrels, which store food in larderhoards (an accumulation of food items in one large storage area). Because many of the buried seed caches are not retrieved before sprouting as seedlings, squirrels play an important role as seed dispersers. Squirrels are active throughout the year, but their activity patterns shift with the season. During the summer months, squirrels are most active in early mornings and evenings. During winter months, they forage during the middle portions of days. Foraging behavior varies with season, but on average, squirrels spend 60-90% of their active time foraging (Gurnell 1987). Squirrels perform a suite of behaviors that communicate information to conspecifics. These include vocalizations, cheek-rubbing, tail-flicking, foot stamping, etc. What behaviors do you see during our trapping sessions?

WLF 315 Wildlife Ecology I Lab Fall 2012 Fox squirrels produce 2 litters of 2-4 young/year. The first mating period begins in late December and young are born February-March. The second pulse of births occurs during June-August (Long 1995). Gestation is about 45 days, and sexual maturity is reached in 10-11 months. Survival of the young depends largely on availability of food. Usually, only 15-25% of young survive to their second year (Gurnell 1987). Predators of fox squirrels include raptors, weasels (Mustela spp.), foxes (Vulpes vulpes and Urocyon cinereoargenteus), bobcats (Lynx rufus), and snakes. In captivity, fox squirrels have lived for <13 years (Gurnell 1987), but survival for wild individuals is likely shorter. The study that this class is involved in will be continued each fall, and we will build up information about numbers and survival of fox squirrels on the UI campus. References: Allen, D. L. 1943. Michigan fox squirrel management. Michigan Department of Conservation,

Game Division Publication 100, Lansing, USA. Gurnell, J. 1987. The natural history of squirrels. Facts On File Publications, New York, New

York, USA. Long, K. 1995. Squirrels: a wildlife handbook. Johnson Books, Boulder, Colorado, USA.

WLF 315 Wildlife Ecology I Lab Fall 2012

Lab Exercise: Trapping and marking fox squirrels (Sciurus niger)

Reading Assignment (both posted on the class website): 1. Arenz, C. L. 1997. Handling fox squirrels: ketamine-hydrochloride versus a simple restraint.

Wildlife Society Bulletin 25:107-109. 2. Powell, R. A., and G. Proulx. 2003. Trapping and marking terrestrial mammals for research:

integrating ethics, performance criteria, techniques, and common sense. Institute for Laboratory Animal Research Journal 44:259-276.

Exercise Expectations: 1. Participate actively in the field exercise. 2. Read assigned material and learn capture and marking procedures for mammals (large and

small). 3. Complete data sheets for all squirrels that you trap and mark, and turn them in at the end

of lab. 4. Complete the resight exercise and email the data to Bill (wseybold@uidaho.edu) on or

before 23 October 2012. 5. Complete the take-home assignment and turn it in to Bill (or his mailbox) by 23 October

2012.

Methods: 1. Form groups of 2-3 students. 2. Read this handout thoroughly and be sure you understand the methods before starting.

Choose which student will accomplish each task. Rotate the duties with each capture. 3. Set a Tomahawk wire box trap at the base of a tree or in bushes, as appropriate. Bait each

trap with peanut butter and rolled oats. Place the bait at the very back of the trap. Find a comfortable spot to sit and watch your trap (and squirrels) from a distance (>25 m).

4. When a squirrel is caught, place a towel or cloth over the trap to calm the animal. 5. Wearing gloves, place the canvas sack/funnel over the end of the trap. A second student

(also wearing gloves) should lift the trap and gently shake the squirrel into the sack. Guide the squirrel towards the opening and allow its head to protrude. Apply gentle, but firm, pressure to immobilize the squirrel while in the sack. One person should remain in control of the animal at all times.

6. One member of your group should apply the ear tag in the LEFT ear. Make sure you record the tag number.

7. Lift the back of the bag to expose the back end of the squirrel, and apply a dye mark to the flanks of the squirrel with a magic marker. A large “X” is sufficient. You may have to rub the mark on repeatedly to make it visible.

8. Examine the squirrel for sex and age (see below). Be careful to secure the hind feet gently while examining the ventral region.

9. Release the squirrel carefully by unzipping the bag while still applying gentle pressure. Once the zipper is opened, remove your hands and step away from the sack.

WLF 315 Wildlife Ecology I Lab Fall 2012 Cautions: 1. Students should wear gloves at ALL times when handling or working with the squirrels. Fox

squirrels can bite (hard) and scratch. 2. Be calm, confident, and speak quietly when working with the animals. Use firm, but gentle

pressure while handling the squirrels. 3. Keep the squirrel under control until you are ready to release it. Professionalism: When undertaking a study that involves capturing and marking wild animals, the reasons that necessitate handling the animals should be clearly defined and potential negative effects of capture or marking should be considered. Any time an animal is handled, there is the risk of injury or death. Precautions should be taken to protect both the animals and people participating in the exercises. It is the responsibility of the wildlife professional to minimize the impact on animals and to ensure the safety of his or herself and others. Please be respectful of the animals, your classmates, and others in the area during this lab exercise. Data Recording: Record data for each trapping session on a data sheet. Record additional comments in the last column of the table and/or below the table. Such comments might include observations of anything that seems unusual about an animal, animal condition, interesting behaviors, or some trouble with a trap. If you capture a squirrel that has already been tagged, record the tag number and release the animal. If the ink mark is not bright, you may re-apply the ink to the same area before releasing the squirrel.

Sexing and aging squirrels: Body size can be used to estimate age. However, there is considerable overlap in weights and size, so examination of the sex organs is necessary. Hairiness of the ventral surface of the tail also can be used to estimate age. Females: Immature: Females born this year will have undeveloped nipples that appear white and small. Adult: Females > 1 year of age who have nursed a litter will have larger, dark nipples, and the hair will be worn off around the nipples (Allen 1943). Males: Summer-born immature: Males born during the summer of this year will have testes that are still within the abdomen (not descended) and the scrotal skin will show minimal pigmentation. Genital size < 4 cm. Spring-born immature: Males born during the spring of this year will have relatively large testes and the scrotum will have some pigmentation, but will have thick fur. Genital size 4-6 cm. Adult: Males > 1 year of age will have large testes and the scrotum will be darkly pigmented and largely hairless. Genital size > 6 cm.

WLF 315 Wildlife Ecology I Lab Fall 2012

WLF 315 Wildlife Ecology I Lab Fall 2012

Fox Squirrel Lab Exercise

Lab Section (circle one): Mon or Tue Date: ____________________ Group Members: Weather: ___________________________ Captures:

Ear Tag #

Sex (M/F)

Age Class (A/J)

Weight of

Squirrel in

Pouch (g)

Weight of

Empty Pouch

(g) Comments

Additional Comments: