Monitoring Caribou on Alaska’s North Slope

Pipelines on the North Slope are installed at least seven feet off the ground to allow the caribou easy passage underneath.

On Alaska’s North Slope, caribou are one of the primary sources of food for Indigenous Peoples. So it’s only natural that the potential impacts of oilfield development on caribou abundance and distribution is of interest to North Slope residents. ConocoPhillips has been monitoring caribou movement and distribution in our areas of interest on the North Slope for decades. We also partner with the North Slope Borough and the Alaska Department of Fish and Game (ADF&G) to collect data about caribou movement and migration. Data gained through this collaborative work informs science, engineering design and best practices for operations and new project development.

Caribou at CD-1.
Caribou at CD-1.

To monitor the movement of the two primary caribou herds, ConocoPhillips Alaska funds the purchase of radio telemetry collars and works with the ADF&G to place them on caribou. Using the data from the collars, individual animals are tracked to assess if their seasonal movement may be influenced by factors including oilfield activities, snow levels, vegetation, terrain, insect harassment or proximity to the coast. The shared data provides detailed information on which areas caribou use consistently during different seasons year-over-year, how those areas correspond with proposed development, and if movement patterns change after construction.

“Simply put, it helps give us the big picture – shows us where the herds are moving and how they’re doing. Knowing this helps inform infrastructure decisions,” said Senior Environmental Coordinator for Biological Sciences Christina Pohl. There are “tens of thousands in each herd.”

"Understanding how to coexist with the caribou is one of our top priorities,” Pohl continued. “By using science to inform operational decisions that may impact caribou or other animals we can best ensure that our activities don’t interfere with the animals.”

Throughout the years, ConocoPhillips Alaska has improved oilfield facility design to accommodate caribou and developed best practices for operations to reduce potential for impacts. There is now a minimum spacing requirement between roads and pipelines, coating on new pipelines to reduce shine or glare, and speed limit restrictions. Pipelines are installed at least seven feet off the ground to allow the caribou easy passage underneath.

Infrastructure placement may also be influenced by the collected data, including where drill sites are located and the height, shape and location of roads. One study focus area in 2021 was the Bear Tooth Unit, which includes the proposed Willow development and a region to the south. Most caribou in this area are from the Teshekpuk Herd, which has significant numbers of the herd remaining on the Coastal Plain during winter, in contrast to the Central Arctic herd in the Kuparuk and Prudhoe Bay areas, which mostly migrate further south for the winter. Although caribou distribution and movements vary widely by season, most calving of the Teshekpuk herd occurs near Teshekpuk Lake, over 20 miles from the proposed development area. The Bureau of Land Management (BLM) National Petroleum Reserve-Alaska (NPR-A) Integrated Activity Plan requires caribou studies prior to construction to understand how caribou use the area.

Researchers in other studies noted that the area north of Teshekpuk Lake is a popular area for caribou to escape mosquito harassment. Caribou monitoring and subsistence harvest studies will continue throughout the proposed Willow project’s lifetime to inform continued caribou protection practices.

ConocoPhillips began monitoring caribou movement and distribution in the Kuparuk area in the late 1970s, including aerial surveys in the area from 1993 to 2017. In 2021, we continued annual monitoring to assess the Central Arctic Herd near our Kuparuk and nearby Alpine oilfields. 2021 data indicated that the herd moved through the oilfields repeatedly during early and midsummer and some large groups were on the Colville River Delta in June and July. The results were generally consistent with previous studies in the area showing different behaviors and response to oilfields during different seasons. For example, during the calving period of about two weeks in early June, caribou tended to avoid roads and pads, but the avoidance declined significantly after calving. In late June and early July, caribou moved rapidly through the oilfields and crossed roads to reach coastal mosquito-relief habitat directly. In late July and early August, many caribou favored gravel roads and pads to avoid harassment by oestrid flies, before they started their fall migration into the Brooks Range.

Significance to hunters

A healthy and stable caribou population is important to communities on the North Slope and their subsistence lifestyle. In addition to monitoring the caribou, ConocoPhillips has sponsored a Caribou Subsistence Monitoring Study in Nuiqsut for the past 14 years. This study showed that subsistence harvests remain strong and that a sizable number of hunters are utilizing the Alpine and Greater Mooses Tooth roads to improve hunting access. The study also provides information about how to improve our operations, such as coordinating helicopters to avoid hunters, and designing subsistence pullouts and ramps in appropriate locations and configurations for access to the tundra.

“Our goal is for our operations to not disrupt either the animals or the hunters,” Pohl said.