PRBO Conservation Science presents Los Farallones

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What do gulls eat? 

 

 

Western Gulls.  Photo: RJ Roush

‘Much that is good and all that is evil has gathered itself up into the Western Gull.
…cruel of beak and bottomless of maw…this gull asks only two question of any other living thing: First, “Am I hungry?” (Ans. “Yes”) Second, “Can I get away with it?” (Ans. “I’ll try).’ 

So wrote naturalist William Leon Dawson in The Birds of California in 1923, and a brilliant demonstration of that bottomless maw is found in the SEFI Gull JuJu Archive.  The Archive, cherished for posterity in a tin box in our data room, is a random collection of strange and interesting objects brought to Southeast Farallon Island by gulls.

 

The Archive.  Photos: Scarlett Hutchin

The gulls don’t often carry things around in their bills for long, preferring to swallow them first and ask questions later, so it’s reasonable to assume that everything in the Gull Juju Archive has probably been swallowed and regurgitated by a gull at least once.  Things like a six inch plastic toy hammer, a baby doll leg, a rubber tortoise, a golf ball, a set of vampire teeth, a collection of large fish hooks and four jelly beans still sealed in a bag inside a plastic Easter egg.  

There are fragments of driver’s licences and credit cards, a key, a few toy cars, a pacifier, Lego blocks, marbles, a balloon that reads ‘happy f***ing birthday’, a drinks stirrer from a restaurant in Newport Beach and another from Denver.

And if none of these were impressive enough evidence of the awesome power of the gull’s gullet, SEFI biologist Pete Warzybok tells me that not only has he seen a Westen Gull catch and swallow a flying Rufus Hummingbird, he has also seen one regurgitate a tennis ball.  Yes, seriously, a tennis ball.

Western Gull.  Photo: Scarlett Hutchin

Pinniped Necropsies on the Farallones

(Warning some photos may be a bit graphic)

PRBO Conservation Science, in collaboration with other agencies, performed pinniped (seal and sea lion) necropsies during the 2012-2013 winter season on SEFI. All carcasses were recovered in a safe manner and with minimal disturbance to live pinnipeds. Aborted California Sea Lion (CSL) fetuses were first noticed on the 24 Feb 2013 and by 15 Mar 2013 a minimum of 85 had been documented. Tissue samples of brain, liver, bile, stomach contents, feces/meconium and urine were collected and tests were run for traces of Domoic Acid (DA); a common cause for CSL strandings. One side effect of adult female CSLs affected with DA intoxication is to abort their fetuses. The placentas of pregnant females act as reservoirs for DA and even if the dams have cleared themselves of DA (through urine excretion), it continues to circulate within the placenta/fetus resulting in abortion. Below is a series of photos showing how one of the aborted fetuses was necropsied and photographed with labels in order to document potential causes of death.

Domoic Acid is introduced via the food web to marine mammals and birds through a variety of intermediaries, including both pelagic and benthic organisms that feed on toxin-producing Pseudonitzschia, an algae and the DA source. High numbers of Pseudonitzschia have often been associated with the end of upwelling events or weak upwelling events during warm years along with low concentrations of macronutrients. In both central and southern California, the occurrence of Pseudonitzschia blooms is also suggested to be tied to shorter term climate events such as ENSO and possibly also to phenomena on time scales of the Pacific decadal oscillation (more on DA and its bioaccumulation can be found here: http://channelislands.noaa.gov/focus/dom.html .)

Depiction of bio-accumulation of Domoic Acid up the food chain. Schematic taken from Channel Islands National Marine Sanctuary website.

Microscopic view of the diatom Pseudonitzschia taken from NOAA.gov

 With that said, all samples collected from the necropsied pinnipeds on SEFI resulted in below detectible levels for DA. In re-evaluating the circumstances and taking into account the recent increase in stranded yearling CSLs in Southern California we believe the cause of the aborted fetuses may be related to lack of prey items. In Southern California large numbers of dehydrated and emaciated sea lions are stranding themselves; causing rehabilitation centers to reach carrying capacity (a link to an online news article with more detail can be found here: http://www.nbclosangeles.com/news/local/Sea-Lion-Pup-Strandings-southern-California-investigated-201503511.html ). Agencies involved in monitoring this population believe that the sea lion’s major food item, schooling fish like anchovies and sardines, are currently absent from the ecological system (link to NOAA website with more details to numbers associated with strandings: http://www.nmfs.noaa.gov/pr/health/mmume/californiasealions2013.htm ). Similarly, if pregnant female CSLs are not able to find sufficient food they may abort their fetuses in response to not meeting the energy requirements needed to carry their pups to full term. We suspect this is the reason for the aborted pups seen on SEFI this past winter season.

Rehabilitation center full of yearling California sea lions that stranded from dehydration and malnutrition. Photo taken from wired.com

Figure comparing live California sea lion stranding over the last 5 years county. Purple bars represent 2013 numbers which are significantly higher than all other years. Figure taken from ecowatch.com.

 Mobile marine mammals are considered to be good coastal sentinels for signaling remote or offshore biotoxin events and by examining carcasses there is increased knowledge of mortality rates and causes which allows for a better understanding of population threats and pressures. Information gained includes complete pathology to investigate diseases and parasites, reproductive biology and life history data, pollution, human interactions and normal biology and physiology parameters. These types of sampling opportunities also help validate and increase understanding and interpretation of data collected from wild populations; especially individuals like marine mammals which are not readily accessible.  PRBO will continue to monitor the CSL population as the pupping season approaches in order to aid management decisions.

Pulmonary "pluck" of an adult California sea lion to examine the trachea, primary and secondary airways of the respiratory system, lungs and heart.

California sea lion heart removed from the thoracic cavity.

Contents of the abdominal cavity in an adult California sea lion. Notice yellow splotches on organs - results from tissue collected also confirmed cancer.

California sea lion spleen with discoloration and abscessed growth. Results indicated this animal had cancer.

Necropsy on a fresh dead northern elephant seal weaned pup. Cause of death was likely due to being crushed by an adult male.

Life in Boxes and Burrows

         

From March through August, Southeast Farallon is bustling with seabird activity, some more obvious than others.  The presence of the Western Gulls is undeniable, and it is pretty hard to miss the 250,000 or so Common Murres milling about as you approach the island.  But some species here on the island, being more reclusive and mysterious, don’t make their nesting presence as obvious. One such species is the Cassin’s Auklet.  They nest primarily in burrows and rocky crevices underground and come and go from the island only under the cover of darkness.  Luckily for us, they can also be found nesting in little wooden boxes with PVC pipe entrances and shaded roofs, which are scattered around the island, tucked in among the Farallon weed, lavatera and rocks. 

Cassin’s Auklet in a nest box, photo courtesy of Annie Schmidt.

         PRBO researchers began building and installing these artificial nest boxes in the early 70’s in order to provide additional nesting habitat and to make it easier to monitor the nesting phenology, breeding success, and chick growth rates of the auklets. Since then, the use of artificial nest boxes to monitor the breeding biology of burrow nesting seabirds has become a widely embraced technique.  But, for those of us researchers who depend on these nest boxes for our monitoring purposes; it is important for us to know that the boxes are, indeed, providing an adequate environment for the birds nesting within them.  I am here on SEFI to help PRBO and FNWR consider just that.

A Cassin’s Auklet nest box with shade cover.

Environmental temperatures on the Southeast Farallon Island were exceptionally warm during the 2008 and 2009 Cassin’s Auklet breeding seasons.  These anomalously warm temperatures meant that the artificial nest boxes turned into little hotboxes, which was distressing to some of the auklets nesting within.  In 2009, to help mediate this problem, PRBO researchers created shade structures for all occupied nest boxes and started a pilot study to better understand the differences in temperature experienced by the auklets in artificial and natural burrows.  Initial results showed that natural burrows were significantly cooler than nest boxes but putting shades on nest boxes decreased the nest box temperature notably.  Since 2009, all nest boxes with auklets nesting in them are covered in shades. 

The goal of my project is to take this study one step further.  I want to see if the adult auklets in nest boxes are able to control egg temperature when nest box temperatures are elevated, and how this may affect their hatching success.  

Reaching into an auklet home to switch out an egg.

For my project, I put devices that recorded temperature in hollow artificial Cassin’s Auklet eggs.  I then put the artificial egg in the auklets nest for a couple days to record egg incubation temperature.  The goal of the project was to compare the incubation temperature of auklets in different nest types- natural burrows, shaded nest boxes, and unshaded nest boxes.  Once I have chosen the nests where my artificial eggs were to be deployed, I diligently babysat the auklets real egg in a poultry incubator while the temperature loggers were deployed for seven days. 

 

Cassin’s Auklet eggs, safe and warm in the incubator.

I started my study a year ago and successfully made three deployments of egg temperature loggers during the 2012 auklet breeding season.  Based on my results so far, I have found that the eggs in artificial nest boxes are significantly warmer than those found in natural burrows that there is a significantly correlation between burrow habitat temperature and egg temperature.  However, these variations in egg temperature do not seem to significantly affect reproductive success of the auklets.  In other words, the nest habitat conditions in the artificial nest boxes may be warmer than in natural burrows but this doesn’t seem to be having negative effects on the overall breeding success of the birds.  My sample size is small enough thus far that it is difficult to say for sure though.
 

An artificial egg, ready to go inside a Cassin’s nest box.

The artificial eggs and wire pulling lubricant.

Beyond the science, this study has also given me the opportunity to learn about a lot more than just Cassin’s Auklet incubation temperature.  How do you make a fake Cassin’s Auklet egg?  You ask an art student (many thanks to Kat McKinnon and Philip Priolo of the San Jose State University art and industrial design departments!).  How do you incubate a Cassin’s Auklet egg?  You follow the directions for incubating quail eggs in the incubator package instruction manual.  How do you make a fake egg feel realistic enough so an auklet will want to incubate it without interfering with the temperature of the egg?  You fill it with wire pulling lubricant (don’t know what wire pulling lubricant is?  Don’t worry, I didn’t either until recently). 

This project has also given me the amazing opportunity to spend the season participating in all the other seabird studies that are carried out on this SEFI.  I have learned so much and made some wonderful memories out here.

I just arrived on SEFI for my second season deploying Cassin’s Auklet eggs, in which I hope to increase my sample size and get a better idea of the differences in incubation temperature between natural and artificial nest habitats and how the auklets may mitigate for this.  It is our hope that the results of this study could lead to the design and implementation of new and improved nest boxes of the Cassin’s Auklets on SEFI.  In the meantime, I am so happy to be back out here on this incredible island and I look forward to whatever the season has in store!

Emma Kelsey

PRBO research assistant and graduate student at San Jose State University

Drawing on the the Rock!

 Western Gull, Black Oystercatcher and a Farallon weed leaf

This is  third visit I, Sophie Webb, have made to the Rock or South East Farallon Island (SEFI) in the past 12 months ( in the 80's and 90's I worked as a PRBO intern in various programs out here). My last trip to the island was for two weeks in October when the island was drab brown and gray. After the the winter rains the island is returning to the yellow dotted lush green of its springtime Farallon weed cloak.

View of Saddle Rock from the lighthouse

Farallon weed

My stay out here is short in comparison to most of the interns, a mere two weeks. Although this time of year  is considered the “slow” season I have found plenty to do and to look at. My time is split between helping with some of the long term data collection, as all interns here do, and working on my own project, a children’s book about SEFI: the wildlife and the research that goes on here (for 5th grade and up). So I spend a  portion of my day  sketching  and photographing the wildlife.

Most of the focus of this time of year is on the breeding Northern Elephant Seals, so  they are of course the subject of many of my sketches and photos. Their bodies are somewhat amorphous and change shape little, beyond getting incredibly round, (pups), 

A weaned pup

Another fat weaned pup

or quite thin like the cow below.

A cow leaving the colony and her now weaned pup post breeding, notice how the area between her shoulders and pelvis is now concave

Their bodies may not change shape much but  elephant seals'  faces are endlessly enthralling. I suppose it is the large liquid brown eyes and the nose that the females and pups can wrinkle up to alter their expression  and  the huge wobbly inflatable proboscis of the male. 

First there are the cows:

 then there are the pups and immatures:

And a few of my sketches of them:

  cows and pups

 Mostly weaners

Cows and pups

Pups

 and a few bulls:

 Two young bulls fight on the Marine Terrace in front of the PRBO house

Bulls fighting, advertising and resting:
what a nose!

A few more sketches:

-07 rests on the marine Terrace

 Bull advertising, a bawling pup and angry cows

Mating: the cows are dwarfed by the bulls

 At this time of year not only are there Elephant Seals on SEFI but several of the breeding seabirds begin to   return sporadically  to the island . Most nights since I have been here, the Cassins Auklets have come in to sing to each other (really a racket) and begin to dig their burrows. There is evidence of new excavations all over the island. 

 A Cassin's Auklet at night near the path to the Coast Guard house

On my last night on the island during our friday night camel cricket census:

A group of juvenile crickets

A beautifully patterned adult female  camel cricket, note the long ovipositor extending off the back of her abdomen . This species is endemic to the Farallones

we surprised a Rhinoceros Auklet with its striking facial plumes,

Rhinoceros Auklet in full breeding regalia by Spooky Cave at night

There are days, who knows what triggers them, when tens of thousands of Common Murres also return, filling up their nesting areas on Shubrick Point and Fertilizer Flat.

Murres flying off of Shubrick Point in the early morning

 Common Murres on Fertilizer Flat February 11th

  Common Murres

 Many of the Pelagic Cormorants' facial skin has flushed red and they have the white flank patches of  breeding plumage: a few have begun to fly around the North Landing cliffs with bunches of the Farallon weed they use to build their nests in their beaks.

Pelagic Cormorant

All around the edge of the island, in the intertidal, Harbor Seals  haul out or play in the water, perhaps the latter pre-copulatory interactions. They will begin pupping in March.

  A hauled out Harbor Seal enjoys the cooling spray at North Landing

Two young seals "playing" in Garbage Gulch

Harbor Seals have beautiful extravagant whiskers . 

Harbor Seals hauled out near East Landing

100's of California Sea Lions and Steller Sea Lions  loaf about on the rocks. The air is filled with the noise of their constant barking and growling:

California and Steller Sea Lions (the latter the large pale animal in the upper right) in Sea Lion Cove

California Sea Lions

California Sea Lions,: the head of a sub-adult male at the top shows the beginning of the exaggerated  forehead formed by their enlarged sagittal crest

Unlike the elephant seals it is the odd shape of the sea lions' bodies that I find interesting to draw, their faces are lovely but not nearly as plastic as those of the elephant seals. The same is true for the Northern Fur Seals that we saw on our visit to West End. I like in particular how their long floppy flippers fold and droop. Although I think the fur seals long whiskers and aggressive attitude make their faces somewhat more expressive than the California Sea Lions or perhaps it's simply that they  are more interesting by being less common.

Northern Fur Seals on West End

 Several species of shorebirds make the Farallones their winter quarters

A Willet,  several Whimbrels and Black Turnstones roost on Low Arch Terrace

Black Turnstones are stocky and somewhat plain looking until.....

they fly

 Whimbrels and Black Turnstones roosting

Black Oystercatchers both winter and breed on the Farallones

Birds do not solely find refuge on the island itself but 100's of Eared Grebes spend the winter on the surrounding ocean  as do Pacific Loons and a few ducks.

One of the dense flocks of Eared Grebes that feed throughout the winter around the island

A male Red-breasted Merganser posing at North Landing

At this time of year  there are still a few landbirds about, some Audubon's Warblers, a couple Fox sparrows, several Black Phoebes and Rock Wrens and at least four Peregrine Falcons. One odd bird  that I believe has been here since early November is a Rough Legged Hawk. It spends its time soaring around or perching on Tower Point. Now that most of the mice seem to be gone, I wonder what it is eating?

Rough-legged Hawk soaring over Tower Point, viewed from the lighthouse.

This blog entry brings my time on the Farallones to a close. It has been a wonderful  two weeks of fine weather,  wildlife and the good company of Ryan Berger, the PRBO Farallon biologist, and the two winter interns Erin Pickett and Nick Sisson.

The Northern  Elephant Seal seal cows are leaving, weaning their pups to begin their"winter" as the seabirds slowly begin to ramp up to their breeding season. The Farallones is a remarkable place, year round it teams with life and the unexpected. Plus where else could one see Northern Fulmar, Northern Fur Seal, Northern Elephant Seal and Northern Gannet all in a single day!

The Northern Gannet

A view of Saddle Rock from the steps of the PRBO house one sunny afternoon