Conservancy Times: Helping the bison herd during the California drought

Bison were first brought to the Island for a movie in 1924, and there’s been a herd of them on Catalina ever since.

The Catalina Island Conservancy, which protects 88 percent of Catalina Island, owns and manages the bison to protect the herd and the Island’s resources.

The bison are not native to Catalina and are registered as livestock, rather than wildlife.

Under California law, people can feed livestock, like the bison.

Bison were first brought to the Island for a movie in 1924, and there’s been a herd of them on Catalina ever since.

The Catalina Island Conservancy, which protects 88 percent of Catalina Island, owns and manages the bison to protect the herd and the Island’s resources.

The bison are not native to Catalina and are registered as livestock, rather than wildlife.

Under California law, people can feed livestock, like the bison.

But California law prohibits the feeding of wildlife, like Catalina Island fox and the deer, which are actually managed by the State of California.

This year, the prolonged drought has dried up the bison’s food and water supplies.

To protect this iconic species, the Conservancy is providing food and water to the herd and seeking donations to help pay for these additional supplies and unplanned expenses.

The Conservancy is shipping hay to the Island to feed the bison.

It also has placed water troughs around the Island and is replenishing the supplies in those.

Each feed shipment costs $8,000, and we’re not certain how many shipments may be needed before winter rains restore the grasses on which the bison feed.

In their native areas, bison feed heavily while resources are plentiful and store additional fat reserves in preparation for the winter.  They also have the ability to migrate to other areas when certain resources become limited.

On Catalina, however, severe drought is not an annual occurrence, and the bison here do not prepare for food scarcity in the same manner. The severity and duration of this drought is well-known. Although the Conservancy has implemented measures to maintain the herd at a reduced population of 150 individuals, there is concern that there is not enough food for them to maintain a healthy body condition through the remainder of the summer.  

The use of a contraceptive vaccine to manage the herd’s size has reduced the burden of pregnancy and calving on the females.

But additional support is still needed to get them through this period. The bison herd has grown and shrunk over the years, depending on food stocks and the Conservancy’s management.

With no natural predators, the herd grew to as many as 500 at one point. The Conservancy had previously commissioned a study by the University of North Dakota, which found the Island could reasonably support 150 bison.

To control the herd’s size, the Conservancy had been periodically conducting roundups and shipping bison to the mainland. But the shipments were costly and caused stress for the bison.

The herd also grew beyond ecologically sustainable numbers between shipments.

The Conservancy launched an innovative contraceptive program in 2009 that has proven to be an effective and humane alternative for protecting the Island and preserving a herd on Catalina.