Mammalian ecology slides

N

Estimated number of individuals

M

Number of individuals marked in session 1

n

Number of individuals captured in session 2

m

Number of individuals recaptured in session 2

Lincoln-Petersen Method

N=M(n+1)/m+1

Lincoln-Petersen Method Assumptions

• Population is closed

▪ Marking does not affect

probability of survival

▪ Marking does not affect the

recaptures

▪ Marks are not lost, gained, or

overlooked

Edge Effect

Animal home ranges overlap the edge of a sample area, causing population density

estimates to appear higher than reality

Leukemism

Brown in summer, white in winter

True Horns

Unbranched and permanent

• Found only in males or in both

sexes (usually larger in males)

• Grows for animal’s entire life

Bony core: extension of the

frontal bone

Horn: keratinized epidermis

surrounding core of bone.

Antlers

Bony structures that are

branched

o Shed periodically

• Generally males only

Giraffe “Horn”

Pair of short, unbranched, permanent, bony processes known

as ossicones

o Found in giraffes and male okapi

• Situated on sutures between frontal and parietals

• Permanently covered with skin and hair

Rhinoceros “Horn”

Hair-like horny fibers arise from dermal papillae

o Made up of keratin

• Permanent and not branched

• Cemented together to form single horn