Mountain Lion Aging Techniques A Summary of Observations

Mountain Lion Aging Techniques A Summary of Observations on Tooth Eruption and Wear Characteristics Neil Anderson and Keith Aune Montana Fish Wildlife and Parks, Wildlife Research Laboratory, Bozeman, Montana

Sex Determinations If the carcass is available examine genitalia. Male testes do not lie centrally between hind legs but are far back near the anus. Sex is often mistaken by observers viewing the wrong site. If you are uncertain, palpate for the testes Sex determination can also be made based on dental characteristics of lions. Male and female lions can be differentiated with reasonable accuracy based on canine diameters.

Age Determinations Age classes of lions consisting of kitten, yearling, sub-adult and adult can be assigned to mountain lions based on physical characteristics, tooth eruption patterns, tooth staining and wear. This information will allow biologists to achieve an immediate age classification of lions and validate the age determinations from cementum annuli of the premolar tooth. Cementum analysis should still be performed but can be variable and inconsistent in estimating lion ages. Classification of lion ages will allow biologist to determined if cementum ages fall within expected ranges. Cementum analysis and age classifications made by examining tooth eruption and wear patterns used in combinations can provide managers with valuable information on the age structure of harvested mountain lions and evaluate population recruitment.

Lion Growth and Physical Characteristics • If a whole carcass is available, physical characteristics may support age determination by tooth eruption. • Note – – Spotting and Barring Size Evidence of Lactation Shape and Size of Head

Definitions • CE (Cementum/Enamel) Junction - The point on the canine tooth in which the tooth changes shape and begins to taper to a point • Canine Diameter - The diameter of the canine measured at the CE Junction. • Deciduous teeth - Non-permanent or milk teeth associated with juvenile animals.

Mountain Lion Canine CE Juncture Diameter measured at this location.

Male and Female Determinations Male Diameter greater than 12. 5 mm. Female Diameter 12. 5 mm or less.

Mountain Lion Aging Techniques • May be used to classify lions into three, possibly four, groups (kitten, yearling, sub-adult, adult). • Accuracy is dependant on examiner’s abilities. • Age classification between yearlings and two year olds is less reliable than other classes. • Tooth eruption is used to determine juveniles and yearlings. • Tooth wear and coloration can be used to determine yearling and older classes. • Field techniques are not available to determine the actual age for three year old and older lions.

Age Class Kitten • 0 - 11 months of age. • Characterized by deciduous teeth (up to about 9 months) and partially erupted canines. • Determinations of sex not possible on kitten skulls with deciduous teeth only. • Kittens have spots and tail bars. These marks begin to fade at 2 months and may be gone except in the hip area by 8 -10 months.

Kitten - Approximately 6 months old. Deciduous Canines Note permanent canines just erupting.

Kitten - Approximately 8 months old. Deciduous and permanent canines both present.

Kitten - Approximately 10 months old Canine about 3/4 erupted. CE juncture not past gum line. Deciduous teeth absent.

Age Class Yearling • CE Juncture just becomes visible at about 12 months of age. • Teeth, particularly canines, remain pale pink in color. No yellowing is observed. • Canines become fully erupted. • Incisors show little to no wear. • Transverse black bars may be evident on the legs and can persist until about 2 -3 years.

Yearling - Approximately 12 months Canine about 7/8 erupted. CE Juncture not yet visible but nearly even with gum line.

Yearling - approximately 12 months old Canines pale pink in color. Incisors show little wear.

Yearling CE Juncture just visible below gum line. Canines retain pale pink color.

Yearling Little wear apparent on incisors. Cusps readily evident.

Age Class Sub-adult (Consists of lions in later stages of yearling development up to approximately three years old. ) • Canines fully erupted and CE Juncture readily visible. • Incisors demonstrate increased wear. • Age determination becomes more difficult requiring a sub-adult classification. • Sub-adult designation for age only. Lions in this age category likely able to reproduce. • Transverse black bars may be faintly visible on the legs.

Sub-adult CE Juncture well below gum line. Pale pink color may persist but canines start to whiten.

Sub-adult Incisors starting to show increased wear. Cusps present but becoming rounded and less distinct.

Age Class Adult (Three years old and older) • Canines fully erupted. • Yellow staining often visible on canines. • Wear may be apparent on tip and inside of upper canines of older lions. • Cusps on incisors becoming indistinct. • Incisors are rounded or becoming flattened in older lions. • Males weigh 120 -150 lbs. -Females 80 -110 lbs.

Adult Yellowish staining becoming more apparent on canines.

Adult Canines staring to show wear. Staining is visible. Incisors becoming rounded, cusps less evident.

Adult Wear can be observed on inside of upper and outside of lower canines. Canines become rounded and blunt in appearance with increased age. Incisors become flattened in older individuals.

Concluding Remarks • An age classification should be recorded on each trophy form. • A premolar tooth should be pulled and placed in a tooth envelope. The envelope should then be attached to a copy of the trophy form and submitted to the region where harvested. • The small premolar just behind the canine is the preferred tooth. • Not all lions have premolars.