Working on a comeback

Severe declines in the bighorn sheep population in the San Gabriel Mountains, from 523 counted by aerial surveys in 1981 to 33 in 1999, led the state to begin a restoration program in 2003. By monitoring the sheep and attempting to enhance their habitat, the program hopes to restore the population to a self-sustaining level of 322 sheep overall and quotas of sheep in certain areas for six consecutive years. Higher population counts in recent years are encouraging.

About the bighorns

Horns: Curling of the horns indicates a ram’s age.

Eyesight: Bighorns can see predators more than a mile away and climb rocky cliffs rather than run to escape.

Hooves: Split hooves with a soft center like rubber help in jumping to footholds from as far away as 20 feet.

Escape terrain:

The best habitat for survival has an 80% slope and a sweeping view.

Keys to lambs’ survival

Habitat: Ewes benefit during lambing season (April-June) from new growth on fire-scorched bushes, which contain more protein. This year’s lack of rain will not help with fresh growth.

Mothers care: Ewes travel in groups with their young. A mature ewe leads the other ewes and young to safe bedding and grazing areas.

Lambs: They can climb within a week of birth and are weaned at 6 months.

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Why the declines?

Bighorns have suffered as a result of lack of fires and other changes to habitat in their winter-spring ranges. The Grand Prix and Padua fires burned the eastern ranges in 2003 and may have helped the increases seen recently. Bighorns have also faced an increased threat from natural and human-introduced predators.

Habitat unaffected by fire

- Unburned chaparral allows dense cover for predators.

- Mature plants are large and tough with less protein.

Primary predators

- Mountain lions hide in unburned brush.

- Coyotes primarily prey on lambs.

- Abandoned in the San Gabriels, wild dogs hunt in packs.

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The annual count

Results of helicopter surveys

[Please see microfilm for full chart information]

1981: 523

1999: 33

2007: 142

Ratio of lambs to ewes in March

(lambs per 100 ewes)

1979: 16%

2002: 18%

2007: 62%

Note: Breaks in chart denote that no helicopter survey took place that year.

Bighorns: the latest numbers

Of the 89,104 total acres occupied by bighorns in the San Gabriel Mountains, the winter-spring range consists of about 23,479 acres. This is where bighorns raise their offspring and the population count is done. The ranges are generally below 5,400 feet in elevation, on south-facing steep slopes. The 2007 helicopter survey results:

[Please see microfilm for full map information]

San Gabriel Wilderness: 14

East Fork

San Gabriel: 17

Cattle Canyon: 19

Barrett-Cascade and nearby canyons: 48

Middle Fork

Lytle Creek: 28

South Fork

Lytle Creek: 16

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Recent regional explainer graphics are available at

latimes.com/localgraphics

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Sources: The Smithsonian Book of North American Mammals; California Department of Fish and Game, San Gabriel Mountains Bighorn Sheep Restoration Program

Graphics reporting by LESLIE CARLSON