Wildlife Aging & Sexing

Question 1

Year Class

Answer 1

Year in which an individual was born/hatched

Question 2

Age Groups

Answer 2

of years an individual has lived

Question 3

YOY

Answer 3

Young of the year; individuals within the first year of their lives
- Sub-yearling, fry

Question 4

Yearling

Answer 4

In second year of life

Question 5

Cohort

Answer 5

Group of individuals in a population born/hatched during a specific period of time

Question 6

What are some ways to sex/age fish?

Answer 6

Scales, fin rays, and otoliths

Question 7

What are some ways to sex/age mammals?

Answer 7

• Annuli in dentine, teeth, horns
• Animal pelts
• Sometimes using long bones (e.g. femur and humerus)

Question 8

How are fish scales used for aging?

Answer 8

As scales grow, they produce circular rings called annuli around a centre focus (warmer weather increases growth)

• Warm water = faster growth = rings far apart
• Cold water = slow growth = crowed circuli

Question 9

Annuli

Answer 9

Growth rings on fish scales used to determine age

- False annuli is scale growth variation caused by periods of environmental stress

Question 10

How are otoliths used for aging fish?

Answer 10

• Part of ear bones in bony fish; growth of annuli (circular rings) can have determine age, growth rate, life history

Question 11

Cementum annuli

Answer 11

Annual deposits in mammal teeth used for aging methods; each season rings form (annuli)

Question 12

Annual rings on mammal horns

Answer 12

• Used for aging horned mammals
• Each year the horn grows, rings form on the horns. Rings closest to the skull are the most recent
• Bighorn sheep, mountain goats

Question 13

Using tooth eruption/wear to age mammals (teeth categories)

Answer 13

• Premolars: teeth 1,2,3. Used for cutting food.
• Molars: teeth 4,5,6. Used for grinding food
• Enamel: hard, white, outer surface of the tooth
• Dentine: soft, brown inner core of tooth
• Infundibulum: hollow portion in middle of tooth
• Tartar: brown staining on outside of teeth

Question 14

How are birds aged/sexed?

Answer 14

By using feathers of the wings & tails.

• Adults: primary feathers have rounded and smooth edged tips
• Juveniles: primary feathers have pointedness and frayed edges; base of quill still blue and soft

Question 15

List the names of the different wing feathers

Answer 15

1. Primaries
2. Secondaries
3. Coverts

• Quill: bare shaft of feather
• Retrices: large tail feather

Question 16

Sexual dimorphism

Answer 16

Differences in form or shape due to gender

Question 17

Sexual dichromatism

Answer 17

Differences in color due to gender

Question 18

What are the two techniques used to determine the age of a deer from the jawbone?

Answer 18

1. Tooth replacement

2. Cementum annuli

Question 19

Deer age classes

Answer 19

Fawn (6 months)
Yearling (1 and a half years)
Middle aged (2 1/2 to 4 1/2 years)
Mature (5 and a half years +)

Question 20

Deer aging: Fawn jaw

Answer 20

• Only 3-4 fully erupted teeth
• First three teeth are milk teeth
• Third premolar has 3 cusps

Question 21

Deer aging: Yearling

Answer 21

• Typically have six fully erupted teeth