Spotting cows from space

When looking down upon the Earth through the eyes of a satellite, what would you choose to look at? For students at the University of California Santa Barbara, they watched cows from space.

In a recent paper published in Biological Conservation, a team of students, along with ecologist Doug McCauley, scrutinised satellite images of cattle herds around Point Reyes National Seashore, USA, to track how wildlife and livestock interact.

Their rigorous cow spotting showed that wild elk had learned to avoid cattle in the area, choosing different places to forage in order to coexist. 

As part of a conservation plan, native tule elk were reintroduced into Point Reyes National Seashore in the 1990s, but they quickly moved from their designated wilderness area. The elk could get past cattle fences, which could put grazing pressure on both them and livestock.

“Some of [the elk] actually ended up swimming across an estero and establishing this herd – which is known as the Drake’s Beach Herd – near the pastoral zone of the park, which is leased to cattle ranchers,” says Lacey Hughey, who worked on the project as a PhD student.

“So we were wondering, how do elk and cattle coexist in this landscape?

“The story between elk and cattle is actually pretty complex. We know from other studies that elk and cattle can be competitors, but they can also be facilitators.

“We also didn’t know very much about which habitats elk preferred in this part of the park and how the presence of cattle might influence an elk’s decision to spend its time in one place over another.”

The elk were tracked with GPS collars and elk surveys, but the team still needed data about the cattle. 

“We knew quite a bit about where the elk were, but we didn’t have any information about where the cows were, except that they were inside the fences,” says Hughey. 

“Knowing the precise number and location of cows relative to the elk herd would be necessary to understand how both species interact in a pastoral setting.

“Because the elk data was collected in the past, we needed a way to obtain information on cattle populations from the same time period. The only place we could get that was from archived, high-resolution satellite imagery.”

“After about eight months, we ended up with more than 27,000 annotations of cattle across 31 images.”

The massive feat was not exactly what a new student would expect to be doing in a science lab, but it was nevertheless useful data.

“There were about 10 undergrads involved in the project, spotting cows from space – not your typical student research and always amusing to see in the lab,” says McCauley.

An original article on the research from the university can be read here.

Fast Facts: Point Reyes National Seashore

• The natural sanctuary is about an hour’s drive from San Francisco.
• Elk, plovers, and harbour and elephant seals are all protected in the area.
• Native Tule elk were reintroduced in the 1990s.
• Pastureland is also leased to cattle farmers.

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