The impact of deer on the San Juan Islands

  • Mon Sep 18th, 2017 4:00pm
  • Life

Black-tailed deer are native to the San Juan Islands. Predator removal and modern reductions in hunting, however, have resulted in high deer densities on many islands, including Orcas.

SeaDoc Society will present a portion of a marine lecture hosted with Camp Orkila a few years ago where the consequences of deer overpopulation was discussed. The talk is free and takes place at 7 p.m. on Wednesday, Sept. 20 at Emmanuel Episcopal Church’s Parish Hall in Eastsound.

“People on Orcas care about where they live and care about the natural world around them,” said Ruth Milner, a regional biologist with the Washington Department of Fish and Wildlife’s Region 4, which manages deer on Orcas Island. “I look forward to having an open discussion on the complicated but important topic of deer management.”

Milner will then discuss deer management on the island. An open community forum will take place to discuss concerns and potential options for balancing deer populations with other concerns islander’s have including bird diversity, garden damage, and deer-vehicle strikes.

A recent study conducted on 66 Gulf Islands, San Juan Islands and mainland sites found that the diversity and density of native and culturally significant plant species declined by 38–85 percent as deer density increased. Other studies have shown that this alteration in plant structure also impacts native bird populations. In one study, the number of different songbird species was twice as high on islands where deer density was low compared to other islands with either moderate or high deer densities. Deer reduce native plant density and abundance. As a result, birds that depend on understory plants also occur at lower numbers. This is likely because of reductions in nesting habitat and cover, but also due to decreases in the insects that many birds eat. A study conducted in the Queen Charlotte Islands showed that insect density and insect abundance decreased 6-8 times on islands where deer over-browsed for decades.

This event is hosted by The SeaDoc Society and WDFW.