4-November-2008

Todays weather was windy and cool, and yesterdays rain had ceased. We were able to do some sharkwatching and observed two attacks. One was a Maintop Bay attack on an Elephant Seal. The attack attracted large numbers of gulls and produced a large slick of blood and oil in the water. The shark itself was seen thrashing at the sight for several minutes. This shark season thus far has been dominated by attacks on the smaller California Sea-Lions which are usually less dramatic.

In bird news we had a few new migrant arrivals, including a flock of 9 American Pipits and a Lapland Longspur. The windy weather was favorable for pelagic species and the seawatches were productive. A trio of geese (2 Cackling and 1 Greater White-fronted) have been hanging around on the marine terrace for several days now. They are a welcome addition to an otherwise slim list of migrants.

Location: Southeast Farallon Island
Observation date: 11/4/08
Number of species: 34

Greater White-fronted Goose 1
Cackling Goose 2
Pacific Loon 4
Eared Grebe 57
Pink-footed Shearwater 23
Buller's Shearwater 2
Sooty Shearwater 1
Black-vented Shearwater 1
Brown Pelican 73
Brandt's Cormorant X
Pelagic Cormorant X
Peregrine Falcon 4
Black Oystercatcher 29
Wandering Tattler 1
Willet 1
Whimbrel 3
Black Turnstone 56
Black-legged Kittiwake 2
Western Gull X
California Gull 104
Herring Gull 5
Thayer's Gull 1
Glaucous-winged Gull 2
Pomarine Jaeger 2
Common Murre X
Burrowing Owl 2
Black Phoebe 10
Say's Phoebe 3
Rock Wren 2
European Starling 24
American Pipit 9
Yellow-rumped Warbler (Myrtle) 2
White-throated Sparrow 1
Lapland Longspur 1

3-November-2008

Strong SE winds were kicking up in the morning and it was cloudy, but not many birds were migrating in front of the today's storm. By noon, it started raining and by the end of the day, we'd received nearly an inch. This provided lots of necessary drinking water for next year. Hopefully we'll get a lot more rain this winter.

The strong winds did bring one species in good numbers though. Today was the first day of Murre Madness. Once the murre parents have abandoned their young in late fall, wind events bring murre adults back in mass to the island. Today was the first day of this madness so only 1% of the breeding population returned to the island. Most of these birds were just sitting on the water near the island screaming "AAHHHH," but a few actually landed on the backside of Sugarloaf.

The only migratory birds of note today were the Cackling Geese and the Black-vented Shearwaters.

Location: Southeast Farallon Island
Observation date: 11/3/08
Number of species: 31

Greater White-fronted Goose 1
Cackling Goose 37
Pacific Loon 5
Horned Grebe 1
Eared Grebe 25
Pink-footed Shearwater 13
Buller's Shearwater 7
Black-vented Shearwater 22
Brown Pelican 392
Brandt's Cormorant X
Pelagic Cormorant X
Peregrine Falcon (Continental) 2
Black Oystercatcher 49
Wandering Tattler 2
Whimbrel 6
Black Turnstone 29
Least Sandpiper 1
Red Phalarope 32
Western Gull X
California Gull 95
Herring Gull 2
Glaucous-winged Gull 2
Common Murre 2000
Black Phoebe 7
Say's Phoebe 1
Rock Wren 1
European Starling 1
Yellow-rumped Warbler 1
Savannah Sparrow 1
White-throated Sparrow 1
Golden-crowned Sparrow 1

This report was generated automatically by eBird v2(http://ebird.org)

2-November-2008

The day after a big storm usually brings strong NW winds and no birds, but we were actually between storms and so we were blessed by light winds and decent visibility.  The best two arrivals were a male Blue-winged Teal and a female Black-throated Blue Warbler.  These are both vagrants from the east.

Although, the Blue-winged Teal is far more common in California during the fall, it is much more rare on the Farallones - there were only 8 previous records.  This individual was an adult male with a white crescent on a blue face so it was easy to separate from its close, western relative the Cinnamon Teal.  Unfortunately, it was only seen well by one person on the island so the rest of us don't get to count it on our Faralist.  Oh well, we'll just have to spend another 5 years or so to see the next one.

Although the Black-throated Blue Warbler is far more rare in California than a Blue-winged Teal, there are many more records of it on the Farallones.  In fact, this one was the 127th record for the island.  This individual was a female, which looks quite different than the male.  The female, as can be seen in the photo, is a little, brown bird with yellowish buff underparts and a thin, white supercilium. The white patch at the base of primaries was quite large and may indicate that this bird was an adult.

Location: Southeast Farallon Island

Observation date: 11/2/08

Number of species: 35

Greater White-fronted Goose 1

Cackling Goose 2

Blue-winged Teal 1

Pacific Loon 5

Eared Grebe 1

Pink-footed Shearwater 9

Buller's Shearwater 29

Sooty Shearwater 11
Black-vented Shearwater 44

Brown Pelican X

Double-crested Cormorant 1

Peregrine Falcon (Continental) 2

Black Oystercatcher 45

Wandering Tattler 1

Whimbrel 9

Ruddy Turnstone 1

Black Turnstone 66

Least Sandpiper 3

Heermann's Gull 2

Western Gull X

California Gull 70

Glaucous-winged Gull 1

Common Murre X

Rhinoceros Auklet 1

Burrowing Owl 4

Black Phoebe 8

Say's Phoebe 2

Rock Wren 1

House Wren 1
Black-throted Blue Warbler 1

Yellow-rumped Warbler (Myrtle) 1

Clay-colored Sparrow 1

Song Sparrow 1

White-throated Sparrow 1

Western Meadowlark 2

This report was generated automatically by eBird v2(http://ebird.org/)

1-November-2008

Today was the first big storm of our upcoming rainy season.  We collect all of our own water for drinking, bathing, and other household stuff on a big, cement catchment pad located on the east side of the island.  During the summer when the rains stop, the Western Gulls like to roost in large numbers on this catchment pad.  The excrement that fouls the pad and other debris (dry soil, feathers, gull juju) blown there by strong summer winds all needs to be scrubbed off during the first big storm of the rainy season to get it ready to collect water.  So, we all grabbed a stiff-bristled broom and scrubbed the pad during the heavy downpours for about 6 hours.  In total, we received about an inch of rain, which is just about the right amount to clean the pad.

Since the rain did not really start coming down until nearly noon, we got a little birding in during the gusty SE winds.  The most interesting birds were the Black-vented Shearwaters seen while seawatching. This species is usually more southerly, but for some reason good numbers were around the island for a few days.  Normally their numbers increase in the north when the sea temperature increases such as during an El Nino event.  But ever since the big blow we experienced back in early October, the sea surface temperature has been quite normal (~12.5 degrees Celsius or 54.5 degrees Fahrenheit).

Location: Southeast Farallon Island
Observation date: 11/1/08
Number of species: 35

Greater White-fronted Goose 1
Brant 2
Cackling Goose 16
Green-winged Teal 1
Pacific Loon 1
Eared Grebe 47
Pink-footed Shearwater 3
Buller's Shearwater 198
Sooty Shearwater 2
Black-vented Shearwater 9
Brown Pelican 15
Brandt's Cormorant X
Pelagic Cormorant X
Peregrine Falcon (Continental) 2
Black Oystercatcher 37
Wandering Tattler 3
Willet 1
Whimbrel 3
Black Turnstone 31
Least Sandpiper 3
Heermann's Gull 1
Western Gull X
California Gull 231
Herring Gull 4
Burrowing Owl 1
Black Phoebe 8
Say's Phoebe 2
Rock Wren 1
Yellow-rumped Warbler 1
Palm Warbler (Western) 1
Clay-colored Sparrow 1
Song Sparrow 1
White-throated Sparrow 1
Dark-eyed Junco (Oregon) 1
Western Meadowlark 3

This report was generated automatically by eBird v2(http://ebird.org/)

31-October-2008

Happy Halloween!  Moderate northwest winds, low visibility, some rain, and fog conspired to make our Halloween a relatively quite one.  The sole new arrivals were a pair of Clay-colored Sparrows.

Holidays on the island are always a little different.  For example, this Halloween, no one dressed up, and we had zero kids trick or treating.  Although we didn't specifically celebrate this year, we did acknowledge the holiday by decorating the front stoop with a couple of pumpkins.

The spookiness that Halloween brings to the mainland is felt out here nightly.  Numerous biologists have reported encounters with ghosts while on the island.  One of the rooms is inhabitated by the ghost of a child that died there of  diptheria in 1901.  People have seen the figure of a woman out on the terrace at night.  Standing alone in one of the houses, at night, with the lights off, always sends chills down your spine.  Even though you know that no one else is on the island, you occasionally feel the presence of another person.  Not to mention the fact that the island is surrounded by some of the deadliest predators on the planet, lurking just below the surface. But the single, scariest thing to any fall biologist is the prospect of seeing no new vagrant birds.  It keeps us up at night.  We have nightmares when the island is devoid of passerines.  All we hear is the screeching of Western Gulls and bellowing of Elephant Seals.  How do the winter and summer biologists do it?  It's a mystery to us.

Location: Southeast Farallon Island
Observation date: 10/31/08
Number of species: 37

Greater White-fronted Goose 1
Cackling Goose (Aleutian) 3
Green-winged Teal (American) 1
Eared Grebe 1
Pink-footed Shearwater 4
Buller's Shearwater 5
Black-vented Shearwater 8
Ashy Storm-Petrel 1
Brown Pelican 99
Brandt's Cormorant X
Pelagic Cormorant X
Peregrine Falcon (Continental) 2
Black Oystercatcher 33
Wandering Tattler 2
Willet 2
Whimbrel 9
Black Turnstone 61
Heermann's Gull 1
Western Gull X
California Gull 325
Herring Gull 11
Thayer's Gull 1
Glaucous-winged Gull 1
Common Murre X
Burrowing Owl 2
Short-eared Owl 1
Black Phoebe 7
Say's Phoebe 2
Rock Wren 2
House Wren 1
Yellow-rumped Warbler (Myrtle) 2
Palm Warbler (Western) 1
Clay-colored Sparrow 2
Song Sparrow 1
White-throated Sparrow 1
Dark-eyed Junco (Oregon) 2
Western Meadowlark 4

30-October-2008

The weather looked promising today with overcast skies and light east winds, but there were very few arrivals.  Two birds of interest were the two Red-breasted Mergansers that were found in Mirounga Bay.  The mean arrival date for this species is 24-Nov so these two were on the early side. 

Another arrival was of a juvenile tundrius Peregrine Falcon.  Tundrius peregrines breed on the arctic tundra and winter from Mexico to southern South America.  They differ from the other two subspecies of North American peregrines by being distinctly paler with a thin, dark eyeline and malar stripe.  Unfortunately for this individual, there are a male-female pair of adult peregrines of the continental subspecies, anatum, that forceably evict any peregrine that happens to stopby and look for a meal.  This pair has been defending the island since the first of September.  In 1932, peregrines were reported to have successfully nested on the cliffs below the lighthouse.  Perhaps this pair will stick around into next spring and raise its young on the abundant seabirds that will nest here.

Another bird that has been on the island for a while is this House Wren.  It arrived in late June and has managed to successfully avoid our mistnets the entire fall.  It's funny to watch it fly up and over or out and around the nets.  It probably has flown into all them and managed to escape them so it knows where they all are.  We hope that this bird will find a mate next spring and start a Farallon population of House Wrens.  In fact, this species has done this on a few islands already where some have evolved into separate species such as the Clarion Wren that breeds on Isla Clarion over 700 km off western Mexico.

Location: Southeast Farallon Island
Observation date: 10/30/08

Number of species: 45

Greater White-fronted Goose 1
Green-winged Teal (American) 1
Red-breasted Merganser 2
Pacific Loon 2
Eared Grebe 82
Western Grebe 1
Pink-footed Shearwater 5
Buller's Shearwater 1
Black-vented Shearwater 3
Brown Pelican 158
Brandt's Cormorant X
Double-crested Cormorant 2
Pelagic Cormorant X
Peregrine Falcon (Continental) 2
Peregrine Falcon (Tundra) 1
Black Oystercatcher 41
Wandering Tattler 2
Willet 1
Whimbrel 4
Black Turnstone 58
Heermann's Gull 2
Western Gull X
California Gull 278
Herring Gull 7
Thayer's Gull 1
Pomarine Jaeger 1
Common Murre X
Rhinoceros Auklet 1
Barn Owl 1
Burrowing Owl 2
Black Phoebe 6
Say's Phoebe 2
Rock Wren 1
House Wren 1
American Robin 1
European Starling 13
American Pipit 4
Yellow-rumped Warbler (Myrtle) 2
Yellow-rumped Warbler (Audubon's) 2
Palm Warbler (Western) 1
Chipping Sparrow 1
White-throated Sparrow 1
Dark-eyed Junco (Oregon) 2
Western Meadowlark 4
Brown-headed Cowbird 1

This report was generated automatically by eBird v2(http://ebird.org/)

Bats on Southeast Farallon Island

The morning of October 14, 1987 on Southeast Farallon Island was like something out of a bat biologists’ dream. To the biologists that lived on the island, it was just one heck of a “bat day”. Although hoary bats (Lasiurus cinereus) had consistently appeared on the island each fall since at least the mid 1960’s, that morning resident biologists saw something unprecedented—101 hoary bats hanging in trees, bushes, and other secluded nooks around the island. Such a landfall of bats may not sound unusual to those unfamiliar with their secretive lives, but to researchers and naturalists who study bats, and hoary bats in particular, the October 14th event is mind-boggling. Biologists can focus an entire career on studying bats and go a lifetime without seeing a hoary bat roosting in the wild, let alone a large group of them. Now island biologists were seeing over 100 in the same place at the same time! Something unusual happens on the Southeast Farallon Island.

Hoary bats differ from most of the 44 other bat species occurring in the continental U.S. in that they migrate across the entire continent of North America each year, roost in trees year-round, and tend to live solitary lives. That’s right; they usually live solitary lives, except during migration. California is an important wintering area for hoary bats, and the island bats are probably southbound migrants that veer off course from Point Reyes as they make their way down the Pacific Coast. Most tend to show up on the island during fall nights with overcast skies, low winds, and low levels of moonlight, and we suspect they are wandering too far from shore and visually cuing in on the light atop the island in an effort to find safe haven from the sea (http://www.fws.gov/sfbayrefuges/farallon/cryan&brown_2007_biocon.pdf). Southeast Farallon Island is the only place in North America where we know that hoary bats consistently show up during fall migration, the only place where they have been roosting in anything other than small family groups (> 4 individuals), and the only place where daytime mating has been seen. Add migratory bats to the list of incredible natural events that happen each year on the island.

PRBO and U.S. Fish & Wildlife biologists began cooperating with USGS bat researcher Paul Cryan in 2003 to try and learn more about the hoary bats on the island. For the past two years we have been deploying an automated bat detector on top of the lighthouse each fall to record the calls of hoary bats during their island stopovers. Visitation was sporadic last year, with only a handful of bats appearing in the trees during the day, but earlier this fall there was a landfall of at least 10 hoary bats during the day and the bat detector recorded more bat calls during the two adjacent nights than we have seen before. We are now analyzing those calls to try and figure out what the bats might be doing around the lighthouse at night, where they have previously been seen circling, sometimes in fairly large numbers. Echolocation calls should give us some indication of whether the bats are feeding during their migration stopover, or interacting in some other way, such as emitting social calls associated with mating and flocking behavior.

Why is all of this important? At about the turn of the millennium hoary bats began taking the lead role in a serious conservation issue facing bats—collisions with wind turbines. Although we are not yet sure exactly why it is happening, bats are colliding with industrial-scale wind turbines all over the world, sometimes at estimated rates as high as thousands of individuals per wind energy facility per year. We have never seen anything like it, as bats rarely collide with other anthropogenic structures. Alarmingly, hoary bats compose more than half of the bat fatalities at wind turbines in North America and they consistently show up beneath turbines at nearly every wind energy site adequately monitored for bats. It is unclear how many hoary bats might be out there roaming the continent, so it is difficult to assess the cumulative impacts of wind turbines on their populations, but it is entirely possible that turbines are increasing mortality to a level beyond what their relatively slow reproductive rate (~2 young per year) can offset. Migratory bats that concentrate in certain areas during migration are particularly susceptible to these types of threats.

How does Southeast Farallon Island fit into the picture? Aside from being near an important wintering area and the only place we know where hoary bats are consistently seen during migration, hoary bats appear on the island during a critical time—fall. The vast majority of bat fatalities at wind turbines, and particularly fatalities of hoary bats, occur during late summer and early fall. This led researchers studying the problem to conclude that something important is happening during fall migration in the lives of hoary bats, and therein lays the key to solving the puzzle of their mysterious susceptibility to turbines. Explanations for the susceptibility of bats to wind turbines span the board, ranging from random collisions of large flocks to bats being attracted to turbines as roosting, feeding, or mating sites. Whatever the cause, we hope that by continuing to take advantage of the incredible fall visitation of hoary bats to Southeast Farallon Island,we will move closer to explaining and hopefully solving this pressing conservation problem. Stay tuned for more bat blog news in the coming months and years! For additional info on the subtleties of bats, contact Paul Cryan (cryanp@usgs.gov).