Although many migrant songbirds probably flew right past the island without even knowing we exist, a few hours of good weather on 9 Sept brought some nice surprises such as the Canada Warbler that we eventually caught in the Heligoland mistnet. Other interesting birds seen this day were a pair of Purple Martins flying over the lighthouse, a Baltimore Oriole seen in a cave during an area search, and a Clay-colored Sparrow in Twitville.
Thankfully, some birds that arrived earlier lingered in the bad weather while others that remained may decide to overwinter. While the Farallones has had many species of shorebirds migrate to the islands, only a few species of shorebirds overwinter. The ones that do overwinter usually are ones that can utilize the extensive rocky shoreline such as Whimbrel and Wandering Tattler. During high tide, PRBO biologists conduct a shorebird survey that attempts to locate high tide roosts where large numbers of these "rocky" shorebirds congregate. Other species such as Long-billed Dowitcher turn up at the few small ponds along the water's edge or on the Marine Terrace where there is soil for foraging.
Frequently when we have even semi-decent weather, we see a few migrant insects such as butterflies and dragonflies. These two "ladies" are superficially similar, but if you look closely at the outer part of a forewing you'll notice that Painted Lady has two white spots along the leading edge while West Coast Lady only has one white spot. Over the last few years, Painted Ladies have been far more abundant than West Coast Lady. Although we're seeing a typical number of Painteds (n = 9) over the past 3 weeks, we've had >6 times as many West Coast Ladies as Painteds. Clearly this is a good year for West Coast Ladies!