CAUSES OF NATAL DISPERSAL AND EMIGRATION AND THEIR EFFECTS ON HAREM FORMATION IN MISAKI FERAL HORSES

Misaki feral horses were separated into 2 herds and the difference bet ween dispersal from natal group (natal dispersal) and dispersal from n atal area (natal emigration) was studied. The causes of dispersal and emigration and their effects on harem formation were studied 1979-1994 . The number of horses ranged from 73 (mature males: 8, mature females : 26, young males: 8, young females: 3, colt foals: 6, filly foals: 10 and geldings: 12) in 1979 and 86 (mature males: 14, mature females: 3 7, young males: 12, young females: 7, colt foals: 5, filly foals: 7 an d geldings: 4) in 1994 when the present study ended. All 29 males whic h survived to age 4 years and 58 females which survived to age 3 years left their natal or mother groups at age one to 3. Seventeen of 22 di spersing males and 29 of 39 dispersing females left their natal groups around the birth of their siblings and significant correlations were found between natal dispersal and birth of a sibling. The number of em igrating young males correlated negatively and significantly with the total number of young males in another herd and the number of emigrati ng young females correlated positively and significantly with the tota l number of young females in the natal herd. All 13 emigrating stallio ns which survived to age 5 years formed stable harem groups and a sign ificant correlation was found between natal emigration and harem forma tion. Twenty-three of 35 resident mares formed stable consort relation s with harem stallions and a significant correlation was found between residence and formation of stable consort relations.