Changes at the pier

For the past month the WA Dept. of Natural Resources has had a contractor removing creosote treated pilings from the Woodard Bay Natural Resource Area. Under contract to DNR, Cascadia Research has provided the personnel qualified to monitor the unavoidable disturbance to the harbor seals that haul out at the same site, to ensure that the permitted disturbance 'take' is not exceeded the number approved by Nat. Marine Fisheries.

The sections used by the myotis bat nursery colony is not being removed, but the first 100 ft. section of the pier's decking (the shore side) has been removed to lower the risk from the rotting beams. The pilings remain in this section.

As far as the affect to the bats when they return this spring, the DNR is aware that this is an experiment -- it is any one's guess how much changes to the pier will be tolerated by the bats. When they leave each spring and summer evening, the bats fly under the cover of the pier, leaving only where it ends at the shore. They then fly along the shoreline until they reach the nearby wooded areas and then along the canopy edge or along the road cut as they head to Capitol Lake for the night's work of consuming thousands of insects apiece.

It appears that the bats use the pier as a protective cover from predators (primarily hawks and owls) while they leave the roost in the relatively bright light of dusk. There may come a point when set of conditions required by the bats of this maternity colony are compromised enough to make this site unsuitable. It is already disadvantaged by both the distance from their foraging grounds and the fact that the pier is not a 'warm' roost site.

Changes... time will tell what happens to the largest known bat colony in the state of Washington.

10 days ago, during the middle of the draining of Capitol Lake, the Woodard Bay bat count leaving the roost was 1,200, down from the prior week's 3,000 bats. Now, a week later it was back up to 2,000, about normal for this phase when the young are starting to fly, and moms and their pups leave for other locations around the region.

In the 7 years of counting at the Woodard Bay colony, there has never been a drop then a recovery in this phase of their maternity cycle. Yes, it could mean that some bats perished during the lake draining, and what we are seeing now are the young that make it through that period.

The colony at Woodard Bay is going through its annual shrinking of numbers, but this is later than most years. There was a drop in numbers last week which has recovered some this week, not at all the normal summer pattern. The draining of Capitol Lake in downtown Olympia, the primary foraging location for this nursery colony, could not have occurred at a worse time for these (and many other ) bats in this area. The sudden lack of feeding area may have caused harm to the local bats, and it could explain the concurrent drop in numbers--likely from abandoned young which probably would not survive a prolonged absence of 'mom.' Nursing mother bats have been documented to leave the young at the nursery colony when food is scarce--so at least one of them survives.