Sunday, August 28, 2011

Summer Nostalgia

Around this time of year each year I start developing an intense nostalgic longing for my lazy summer days spent wandering the deciduous landscape of southern Jackson County, usually well before they've even ended.  As the first flocks of Canada Geese penetrate the monotonous chorus of crickets through the soft, humid nights of August, followed by the blooming of Cardinal Flower and the sweet autumn scent of the southern forest, I begin wishing I had just a little more time in the field.


Cardinal Flower

Given that autumn is increasingly becoming my favorite time of year, I think my "summer nostalgia" is more appropriately defined as "not wanting to move my crap back to East Lansing where my days are spent in laboratory basements and not outside watching fall warblers" or "wishing I had a car so that I might actually get to bird in central Michigan".  At any rate, I've been soaking up as much birding time as possible these past few days, and have run across a few good finds along the way.

Sandhill Cranes

I took this photo out on the prairie at Dahlem while on my way to try for a Yellow-bellied Flycatcher that I had found the day before (Sunday) in the marsh/bog type habitat in the northwest corner of the prairie.  While I was unsuccessful in this pursuit, seeing a few decent-sized flocks of Sandhill Cranes flying over was a nice treat.  The cranes also got me looking forward to Friday evenings and Saturday mornings at Haehnle Sanctuary in the Waterloo Recreation Area -- an unrivaled highlight of last year's autumn that saw record-breaking crane numbers and the locally famous Whooping Crane on several occasions.


Tennessee Warbler
Not the buckthorn! 

I always associate fall warbler migration with more Tennessee Warblers than in the spring.  Additionally, most autumn individuals seem to have a lot more yellow in their plumage compared to spring birds.  Sibley depicts first year birds as having more yellow/greenish coloration compared to adult birds, which is also mentioned in this species' Birds of North America account.  According to this account, there is some evidence for an elliptical migration in Tennessee Warblers, meaning some individuals follow a different route north in the spring than in the fall while headed south (Blackpoll Warblers, also more common in fall, do this as well).  However, nothing is mentioned regarding divergent routes between adults and immatures in this species, as is the case in the eastern population of Nashville Warblers.


Magnolia Warbler

Amongst the six or so Tennessee Warblers were a couple of Magnolia Warblers, another species I seem to find more of in the fall.  Arguably one of the most spectacular warblers in breeding plumage, these birds also retain quite a bit of color in the fall.

American Robin

A large hatch of insects clouded the evening sky with a thick blanket of food for all the birds present.  As such, virtually every species had a go at flycatching or "hawking", some more successful than others.  A large flock of predominately immature robins were among the more awkward-looking participants, essentially tumbling downward from high perches only to catch themselves at the last second with heavy, overexerted wing beats.  This first year Baltimore Oriole was only slightly better.


Baltimore Oriole

Yesterday was the Jackson Audubon Society's fall shorebird trip to Pt. Mouillee led by Don and Robyn Henise.  Spare for the weekend trip to Sault St. Marie in February, I look forward to this trip the most each year, as shorebird habitat (and thus shorebirds) are all but absent from Jackson County. 


Wilson's Phalaropes

Among the highlights of the trip, I think these phalaropes really topped the list for me.  From our initial, distant view of them, many of us were thinking Red-necked Phalaropes.  As we approached, however, it became clear that these were actually two juvenile Wilson's molting out of their juvenile plumage.  Closer looks also afforded great views of their feeding habits (no phalroping, however), consisting of horizontal "sweeping" with their bills through the heavy metals of Detroit River sludge.  Several Lesser Yellowlegs also employed this feeding strategy, which I don't know that I've ever seen before.


Convergent evolution?  Imitation?

This next picture reminds me of Sibley's illustrations that demonstrate how microspatial variation in habitat use can be used to help identify shorebirds in migration.  Semipalmated Sandpipers seem to forage from the bare mudflats to very shallow water, Stilt Sandpipers are almost always seen wading a little further out still, and Wilson's Phalaropes can be found in deeper water still, especially when phalaroping, though among phalaropes they seem to prefer shallower waters.

Semipalmated, Stilt, and Wilson's

For whatever reason, I failed to photograph several of the very cooperative and notable birds, including three Buff-breasted Sandpipers, a Hudsonian Godwit, Red Knot, and Merlin that kept shorebirds moving in and out, which, depending on what you happened to be looking at, could either be a blessing or a curse.  One particular air raid scared in a flock of ten or so Baird's Sandpipers, which I managed only a few crappy shots of.



Baird's Sandpiper

After scanning through hundreds of gulls and terns for a juvenile Black-legged Kittiwake that was seen earlier in the day, the group left cell 3 to try for Solitary Sandpiper at the Lautenschager Unit.  We dipped on Solitary, but several Stilt Sandpipers and both Yellowlegs were present.

Stilt Sandpiper

A return to cell 3 for a previously reported American Golden-Plover ended up being very successful, as two individuals were found in the company of a single Black-bellied Plover, offering a great opportunity for studying the structural differences between these two potentially confusing species.  I really wanted photos of this mixed group for further study, but they were simply too far away.  Instead, between extensive study through scopes, I snapped a few shots of this nearby Short-billed Dowitcher.


Short-billed Dowitcher

And finally, in other news, a curlew from Allen Creek was spotted Friday in Oahu!

Tuesday, August 16, 2011

Summer Summary

With fall migration rapidly approaching, I've been a bit eager to finish up with the retrospective posting (which has taken me way too long) and get on with posts that don't require often futile attempts at scouring through pages of chicken scratch field notes.  In light of that, and the completion of my Alaska series, here's a collage of audio and visual highlights of everything I haven't been posting about since being home:


Monarchs!

Northern Water Snake

Spiderwort




Purple Coneflower


Baby Broad-winged Hawks




White-tailed Deer

Henslow's Sparrow

Summit of the Porcupine Mountains


Yellow-bellied Sapsucker


Pictured Rocks


Bad picture of Jackson County's first documented breeding Golden-crowned Kinglet

The (unanticipated) End (6/11/11 - 6/16/11)

Apparently, around mid to late June each year, Allen Creek and the surrounding area is consistently hit with a few weeks of heavy precipitation -- heavy relative to the ubiquitous fleeting afternoon showers that emerge and disappear faster than the flyby Eastern Yellow Wagtails headed for the coast (a calamity of paramount frustration).  Though we weren't receiving quite as much rainfall as is typical for this brief wet period, we began receiving it a bit earlier than anticipated.  In addition to rendering invertebrate collections a freaking nightmare and producing an abundance of spectacular rainbows, these showers also stimulated the early emergence of my biggest fear from the Alaskan tundra -- not a hungry Grizzly Bear poking through my tent late at night or the prospect of pissing off a defensive cow Moose as I bushwacked through willow stands -- mosquitoes.

Yay for refraction!

Kristine and I first noticed the little buggers late one Saturday evening when, in light of crappy daytime weather, we planned to get some behavioral observations after dinner of the incubating male curlew near camp.  With no seven a.m. wake-up call the next day, and the prospect of watching curlews with my beloved evening coffee, I was truly looking forward to a pleasant night.  Within the first five minutes of setting up the scope and pulling out my notebook, however, I had easily squashed over 30 mammoth mosquitoes. While we were all bracing ourselves mentally for the onslaught of these blood-thirsty thieves, we weren't expecting to see significant numbers for at least another week.  If the first five weeks of lugging through waist-deep snow during 13-mile point counts were hell, humankind has yet to conjure up an imaginary scare-tactic miserable enough to parallel what these last five were shaping out to be.

Unpleasant as the arrival of the new denizens of our toilet tent was, the rains also brought with them a tremendous array of life to the tundra.  Napaea Fritillary, Arctic White, and Old World Swallowtails appeared just in time to soothe the woes of dull bird activity, complemented by springing blankets of Shooting Star, Nguyen Berry, Labrador Tea, and Cloud Berry.

Old World Swallowtail

Labrador Tea

And did I mention the Harlequin Ducks?

I'd be jealous, too

It's just come to my attention that I've managed to completely fail to mention these stately sea ducks which, by the way, we saw just about every single day from the comfort of our tents.  Actually, the above picture was taken literally moments after waking up to Jake and Kevork pounding on my tent as they raced to the creek to photograph these birds in the morning light.  Half-blind and half-naked in my outdated glasses and boxer briefs (in 30 degree weather, I might add), shaking from inner excitement and extrinsic temperatures, I somehow managed to make these my best shots of these very skittish birds.

Harlequin Corner

This photo was taken on a different day during one of my favorite Sunday evening activities -- fishing for Grayling.  This particular spot happened to be named Harlequin Corner after Jake discovered three individuals here last year.  The name certainly seemed justified, as virtually every catch of monster Grayling was supplemented with a wary male peeking his head around a corner in the creek, usually with a female close behind.

With curlew behavorial work now reduced to the rare event of happening upon a daytime foraging flock of several parents taking a break from their 12-hour incubating shifts, and three carefully-monitored nests located, the final stage of our work had begun -- capture.  In order to identify birds as individuals (a must for accurate population study and detailed behavioral study), banding as many birds as possible was a top priority for this field season.

Banding curlews is unlike banding any other species that I'm aware of.  It goes without saying that simply setting up a mist net and hoping for the best is an unreasonable strategy.  A strategy I've seen employed for other large shorebird species involves sneaking up on an incubating individual and laying a mist net over the bird (we actually were able to use this method for the few nests we found during incubation).  This is largely doomed for failure if applied to curlews, as finding a single nest is next to impossible given the adults' cryptic plumage and behavior.  Indeed, finding a curlew nest usually entails several hours of observing a suspected breeding pair on their territory from a far yet clear vantage point, as the birds will refuse to associate near a nest in the presence of humans and other potential predators.  The only way to band substantial numbers of curlews relies on finding a pair of adults that are foraging with their recently hatched young and attempting to locate the "brood center" from which one broadcasts a recording of curlew chicks in distress.  As the call is being broadcast, two people stand on either side of the call, mist net in hand, waiting for an adult curlew to fly in towards the recording when they will swing the net up towards the bird and catch it in mid-air.

Not 'capture' per se

However, the only method of "capture" that I was present for involved the much gentler approach of an incubating bird (pictured above).  After banding the female from the first nest we discovered, we headed towards camp to band the incubating female on 'my' nest.


A truly remarkable specimen

This would seem to be an opportune time to give a bit of background on the female of this nest -- the "blue-banded female" as she is known amongst our crew.  We first spotted her mingling around the established territory of a single male curlew some 6 miles from camp very early in the season.  Great looks revealed that she already had been banded on her right femur, just above the tibiotarsus.  We became reasonably confident that she must have been a bird banded during McCaffery's last field work at Allen Creek, given the color of the band and the later discovery of a silver band on her left tibiotarsus.  At this point, the prospect of having found a bird potentially older than myself was mystifying at some level, especially given the rigorous nature of curlew life compared to my own.  A couple of weeks later, we found her again, only this time acting as an apparent "back door woman" at a territory closer to camp that already had an established pair.  While her presence here continued to provoke endless speculation and curiosity amongst our crew, the resident female seemed much less enthused.  Finally, roughly a week later, she seemed to have settled in with the fellow whose nest I discovered, mere yards away from her last known fling.  Whether her bohemian ways represented an aging, unattractive gal unable to secure a mate or a spunky, promiscuous veteran of baby-making will forever remain a mystery -- what I would give to have been able to genotype her eggs against the DNA of her three potential mates.

As Kevork and Jake approached her with the net, Kristine close behind to retrieve her from the net, I stayed far to the side, camera in hand, ready to assist Kristine with the banding and measurements of the bird.  After laying the net down on top of her, the bird only began to flush as we approached her within a foot or so, illuminating just how reliant these birds are on their plumage to avoid predatory encounters.  Having completed standard measurements of her culmen, wing chord, weight, etc. Kristine requested that I hold the bird while she prepared the band!  Slightly nervous about the prospect of losing or injuring the bird due to my clumsy dexterity, I proceeded to grasp the bird closely for several minutes, consistently attempting to calm her with gentle strokes and soft whispers.  How marvelous that bird felt in hand!  Inexplicably light for its size, yet with a keel that upon touch alone, proved this bird's competence in achieving transoceanic flights, rivaled only by the Bar-tailed Godwits of this region.  In all of my countless tachycardic events, not once had I maintained a heart rate even close to this bird's pulse, which easily exceeded 200 beats per minute, further supporting this species' legacy as a long-distance champion of flight.

Later on this same evening, I went out after dinner for what would be my last trek in the Nulato Hills.  Everything about the evening was spectacular, especially given the time of season.  A large flock of calling Glaucous Gulls kettled above camp, a pair of Red Foxes provoked attacks from Long-tailed Jaegars, Whimbrels, Pacific Golden Plovers, and Bristle-thighed Curlews, and passerines were exceptionally vocal in the soft evening light.



Pacific Golden Plover


Cavities being scarce, this Tree Swallow eagerly established residency in our weatherport nest box

My last great experience in the Nulato Hills is attributed to this extremely cooperative White-crowned Sparrow, who spent something on the order of ten straight minutes singing his head off, allowing for great photos and recordings!

What a beaut!


After a terrific evening of natural history, I layed down to the diminishing twilight sounds of Wilson's Snipe and Gray-cheeked Thrush for what was to be the last time.  In short, a night resembling the horror of my earlier jaunt in St. Mary's repeated itself, forcing me to evacuate the Allen Creek field site early.  Feeling very weak, ill, fatigued, and depressed by my early departure, I snapped this last photo of camp as the helicopter departed.

Life in a chosen country, indeed

In the midst of the sometimes grueling nature of field work, we all expressed our fantasies about our return to civilization, centered on how much we missed the conveniences of our homes -- I was often at the forefront of these conversations.  However, there is no describing the impenetrable sadness that overcame me as soon as I heard the distant blades of the refuge helicopter roaring towards me.  I had just spent the last 6 weeks in an area that exceedingly few people will ever even glance at from an airplane in their lifetime, intimately living with and delving into careful study and observation of all of this unique ecosystem's inhabitants.  It is very likely that I will never see the Nulato Hills, maybe even a Bristle-thighed Curlew, ever again.  These are all inescapable facts that I had anticipated at some level, but I suppose I'm most disappointed in my not taking time to sincerely consider these ideas each and every day that I spent in one of the last great wildernesses on this planet.



Monday, August 15, 2011

Have you seen me?

At the off chance that a trip to Oceania is in your future, please see the message below from the Yukon Delta National Wildlife Refuge...

WATCH FOR BANDED BRISTLE-THIGHED CURLEWS ON YOUR PACIFIC ISLAND VACATION

 
The Bristle-thighed Curlew is a rare shorebird that breeds only in western Alaskan and spends the non-breeding season on islands and atolls in the Central and South Pacific. In 2010 and 2011, Bristle-thighed Curlews were marked on their breeding grounds in the southern Nulato Hills of Alaska with coded leg flags as part of an effort to estimate current population size and track survival rates of adult curlews. Birds from this area are known to spend their non-breeding season in the Hawaiian Islands (Hawaii, Oahu, Kauai), Northwestern Hawaiian Islands (Midway Atoll, Laysan and Lisianksi Islands), Marshall Islands, Gilbert Islands, Nauru, and probably the Line Islands. Look for them from August to April.
Leg flags are bright green and have a two-digit code in white. The code consists of either two numbers or two letters. The leg flag is located on the upper leg (right or left), while a standard numbered metal band is on the other leg. We have marked 69 adult curlews with green leg flags. Two flagged birds were observed during the winter of 2010-11, one on Sand Island at Midway and one on Oahu.
PLEASE REPORT ANY OBSERVATIONS OF THESE MARKED BIRDS TO:
Kristine Sowl Phone: 907-543-1027
Yukon Delta National Wildlife Refuge Email: kristine_sowl@fws.gov
P.O. Box 346
Bethel, AK 99559 USA

Wednesday, August 10, 2011

Willows mess everything up (6/4/11 - 6/10/11)

With curlew activity dwindling, days in the field began to truncate, allowing more down-time for everyone.  After dinners of burritos or Alaskan sausage that capped-off our daily 4,000 calorie budgets, I spent most evenings observing Savannah Sparrows' territorial behaviors or trying to catch up on photography and recordings.  On one such evening, as I made a beeline for camp after photographing stands of Arctic Tundra Grass, I flushed a large bird from a tussock mound, its identity initially alluding me in the low evening sun pouring directly into my retinas.  I assumed a female ptarmigan, and braced for an aggressive attack to my face (these birds become extraordinarily fierce while incubating!).

No sooner had my cerebral cortex processed the distinctive wavelengths of light emitting from the bird's rump that it began belting out a series of shrills and cheuit calls -- a curlew!

He don't take kindly to my type 'round here

We were well aware there was likely a curlew nest in this area (no more than 200 yards from camp), as the birds insisted on displaying and vocalizing vigorously the minute we zipped-up our tents every single night (as distracting as this was to attempts at sleep, this behavior made for a truly pleasant wake-up call most mornings).  Even so, I found myself completely dumbfounded at my discovery, clumsily fumbling over my camera in attempt to photograph the bold behavior of this male bird, who was now performing convincing broken wing displays and audacious mob-flights directed towards me.  After realzing that my flustered mind had failed to change the macro setting on my camera from my botanical exploits, I decided I had disturbed this fellow enough, snapped a couple pictures of him and his nest, marked the location with a GPS, and eagerly fled for camp to tell the crew.

The genetic future of a remarkable pair

Having scoured the entirety of the core study area for nests, Kristine and I opted to continue our search at the western edge of the Nulato Hills -- a truly unforgettable experience that led to a repeat, more extensive trip the following day with the entire crew.  Just before abruptly transitioning to flat, pond-dappled tundra for some 60 miles to the Berring Sea, the westernmost hills of the area shoot up some 1,000 ft above sea level, offering spectacular views of the region, as well as a rare glimpse at a (near) sub-alpine ecosystem.

The Nulato Hills/Coastal Tundra divide

The steep ascent to the final ridge of the hils was an experience in itself.  The graminoid hummocks and sedges of the mid-slope landscape gave way to smooth carpets of light green and black lichens.  Anemone, Wooly Lousewort, Alpine Azalea, and Purple Oxytrope were sprinkled along the slope in vibrant clusters, or, in the case of the Anemone, loose stands that hugged the southern light.  Among these dwarfed meadows, an occasional Old World Swallowtail could be found, clinging for precious life in the face of indifferent summit winds.  Two small passerines (likely redpolls) bounced over the very summit, teasing me with the anticipated display of American Pipits that claim these hilltops.


Alpine Azalea and Purple Oxytrope

As we neared the summit, I caught my first glimpse at the flat expanse of tundra that one recalls from Discovery Channel documentaries highlighting the rich diversity of the Alaskan tundra's avifauna.  From an incredible distance, several ponds holding unidentified waterfowl (spare for two obvious Tundra Swans) were visible, leaving me lustfully speculating at breeding loons, wagtails, turnstones, and all the other species unable to colonize the Nulato Hills.


A view much closer to Russia than Sarah Palin's backyard

To my east lie a dark, unintelligible view of the great Andreafsky Wilderness, home of Arctic Warblers, Boreal Chickadees, and Grizzly Bears -- a wilderness I so long to visit.

Waaaay back there -- 'God's Country', as the locals know it

On the 'campside' of the slope, in a thicket of alders and willows that marks the start of the 'P' drainage -- a drainage containing a curlew territority -- Fox Sparrows and Orange-crowned Warblers contributed great notes towards my content, ridding me of woe over the absence of eiders and reassuring me of the richnesss of my home for these final weeks...the flock of ten Long-tailed Jaegers dancing about the hilltops and our first Grizzly Bear sighting certainly helped this matter as well...


The 'P' Drainage

With one important exception that I will address shortly, the above picture, specifically the right side, is a textbook example of prime curlew estate.  The two slopes meet at a snowmelt drainage that begins at the very top of the hill, visible in the foreground.  For whatever reason, these drainages are a must for curlew habitat, and the birds spent a great deal of time in early spring displaying over them, seemingly utilizing the natural boundaries created by the drainage and the willows on the slope to define their territories.  As you'll notice, the entire left slope is entirely covered in willows and alders, whereas the right slope has a few large lichen mat meadows that are divided up by willows lining the smaller drainages running perpendicular to the main drainage.  These open meadows are where the curlews breed, roughly from low to mid slope.  One of the concerns for future curlew conservation is the rapid expansion of willow and other woody shrub species across the Nulato Hills in recent years -- a phenomenom attributed to rising temperatures and subsequent reduction of permafrost, allowing larger shrubs to take root easier.  A good indicator of shrub expansion has been the recent appearance of moose in this area of the hills, as moose are completely dependent on these shrubs for food and shelter to rear their young.  Indeed, during the last curlew study at Allen Creek (1989 - 1991 -- roughly?), Brian McCaffery's crew saw something on the order of three moose throughout the entire season -- a much different scenario than our daily moose sightings in several distinct locations.

While on the topic of willows, I must admit that I found myself extremely fascinated by them after, what I found to be, a very interesting observation.  The sharp-eyed soul will note that in the above photo of the hill/tundra boundary, there is still significant standing snow.  Such snow deposition areas were fairly sparse by mid June, but common at the bottom of a north-facing slope.  Allen Creek, which runs roughly east-west near our camp, is bordered by both south-facing and north-facing slopes, both of which contain willows bordering the creek.  I noticed that willows on the north-sloping side were well behind the willows on the south-sloping side in terms of budding and "leafing-out", sometimes by as much as two or three weeks.  These conditions initially struck me as having interesting potential for sympatric speciation between the willows on opposite sides of the creek.  Given that the life spans of tundra insects are very short, even a difference of a couple of weeks can see a noticeable shift in the species composition of potential pollinators flitting about.  Assuming that the mentioned phenological differences exist between the two groups of willows most years, it seemed reasonable to assume that there could be potential for adaptive divergence via differential "recruitment" of pollinators, not to mention different physiological demands on the plants based on the different lengths of time the two groups are buried in snow (though I'm less confident about that).  This idea came quickly to an abrupt hault when I realized that willows elsewhere in the area, based on their local environment, had intermediate "phenological clocks" between these two groups, serving as a sort of "bridge" to gene flow between them...and that willows hybridize like crazy.  Oh well.

A failed attempt at illustrating the above 

Sunday, August 7, 2011

Pancakes and Beavers (5/23/11 - 6/3/11)

Prior to May, and after learning that I had landed a position on the BTCU project, I spent considerable time digging through available literature on BTCU biology (and range maps, scouting prospective lifers).  One of the several interesting curlew quirks (tool use and flightless molts on wintering grounds, non-stop, pelagic migrations in excess of 4,000 km, and those mysterious bristle feathers -- to name a few) that really caught my attention was the sexual dimorphism in bill size.  On average, and with some overlap, female birds have much thicker bills that tend to curve much less than males.  Indeed, as it turns out, this was the most reliable means of identifying a bird's sex in the field.
Male BTCU profile -- very typical bill size/shape

Female BTCU profile -- actually, the mate of the fellow above (and possibly others!)

So, the question I had, and wanted to learn a bit more about, is why this dimorphism should exist.  Barring something like an epistatic effect of sex, it seems reasonable to assume that this trait represents some sort of adaptive significance.  And while it very well might be tied to some aspect of the bird's biology on the wintering grounds, where, for example, they use rocks and pieces of coral to crack open seabird eggs with their bills (the only known example of tool use by shorebirds!), I figured it was worth examining on the breeding grounds.

Every two days, after enduring exhaustive point counts that sometimes saw 13+ miles of hilly tundra by foot, Kevork and I would alternate roles and work on territory mapping and behavioral observations of curlews (way more interesting -- and easier).  During this time of the year, male curlews (and less often female curlews) stake claim to a slope of lichen-mat tundra via extraordinary aerial displays that entails the birds circling their territory while belting out their complex songs.  One of our primary duties was to construct a map of each bird's territory within the study area, as well as describe the various behaviors of birds in the context of apparent functionality, as so little is known about the life history of these dramatic creatures.

This offered me substantial time to observe what I figured might be a critical phenological time to uncover potential behavioral discrepancies between the sexes that might account for the bill dimorphism.  It seemed intuitively plausible that female birds, after logging some 2,500 miles of non-stop flight, might need to feed more than males in order to accumulate adequate resources for egg-production.  To my amazement, as intuition has not always served me well in science, this is exactly what we observed.  During these first couple of weeks, male birds tended towards the center of their territory, where they would perch conspicuously on an elevated hummock and viciously ward off conspecific intruders, if not already in the air displaying.  Females, however, could consistently be found quietly slipping through the vegetation of the territory's edge, ravenously foraging away and paying little mind to anything else.  How exactly this translates into divergent selective pressures on bill shape, I have little idea, though it is worth noting that at this time of the year, the tundra was still largely covered in snow, and exposed areas were all but frozen solid.  Male birds were not observed foraging heavily until later in the season, after nesting had started.  During this time, it appeared that females tended to incubate during the day, while males tended to work nights.  Again, I'm left uncertain as to how natural selection might be operating divergently in this situation, not to mention if this is even a 'real' phenomenom (this last observation is based only on the few nests we could find).  Nonetheless, I was interested in divergent behavior related to the different roles of each parent in the nesting process, where bills played dominant roles, and I found them.  Whether they have any relevance in explaining this interesting trait is pure speculation, but it kept my mind busy on some of the slower field days!

Interestingly, while bird activity generally started to pick up around this time (though much slower relative to last season, according to Kristine and Jake -- likely due to extensive snow cover over the low-lying willows that many songbirds nest in), with Whimbrels, Long-tailed Jaegars, Pacific-Golden Plovers, and Bar-tailed Godwits having arrived and settled down, Bristle-thighed Curlew display behavior seemed to vanish overnight around mid-May.  This is in stark contrast to last year, when the birds displayed well into the first week of June.  While the dawn chorus of Lincoln's Sparrows, Gray-cheeked Thrush, and Wilson's Warblers was consistently less impressive than last year, curlew activity was very high initially, leading some to speculate that they may have started nesting early despite a late arrival.


Long-tailed Jaeger -- king of the Nulato Hills!

No sooner had the recent influx of breeding birds and gushing snowmelt began to suggest spring that, without warning, the tundra summer was upon us.  The might roar of Allen Creek and her supporting drainages (which, in late May, make for one hell of an adrenaline rush when attempting to cross either by foot or holey inflatable raft) had been reduced to a dull moan, and the only glimpse of a dawn chorus was obtainable at the absurd hour of four in the morning!  Luckily, a maladaptive habit of evening coffee roused my bladder at this exact time most nights, allowing for half-conscious, yet thrilling observations of the awakening tundra.

Yellow Warbler singing, as all Alaskan individuals do, like a Chestnut-sided Warbler

On Sundays, our single day off from the rigors of field work, we all indulged in bountiful, southern-style pancake breakfasts, complete with coffee, sunny-side-up eggs, greasy bacon, and Old Crow Medicine Show.  Jake, being from Tennessee, and I, a nut for southern food and string-bands, conducted these all-too scarce gems of relaxation, which is where the crew's varying geographical backgrounds really seemed to stand out to me.  As a midwestern boy, I found myself at an intermediate position between the southern, conservative tendencies of Jake and the liberal, west coast influence of Kevork with respect to several cultural dimensions.  Jake and I meshed in our love of artery-clogging food and down home bluegrass, while Kevork and I had several agreeable discussions on sustainability and bands like Animal Collective and Girls.  Conversations on politics were rare, for a bit of tension was definitely present, especially with the inclusion of topics like climate change.  While I'm not one for politics (I find the whole ordeal overwhelmingly frustrating), I've always tended to view myself as maintaining a position somewhere between the two extremes with a slight liberal bias -- a position that seems relatively common here at home, which is likely where I derive much of that influence.  Likewise, Jake and Kevork maintained that their opinions were also common amongst their hometown fellows.  For the first time in my life, I actually found myself proud to hail from the corn-laden midwest.

After food comas, a weekly shower, and boastful stories of respective hometown avifaunas (spring wood warbler migration won this category, hands-down), we spent most evenings birding at the legendary Beaver Pond.  Just about every drainage in the study area seemed to have a beaver dam at roughly mid-slope, some of which were the most recent works in a drainage that has hosted multiple dams over many centuries, evident by large mounds of sticks and mud now colonized entirely by various grasses and forbes.  The Beaver Pond was such a place.

The Beaver Pond in all its water-pooling glory

As a birder, one of the most frustrating aspects of the Nulato Hills' undulating topography was the inability of this landscape to hold water.  An absence of large pond-dappled tundra meant an absence of breeding loons, wagtails, and many species of shorebirds.  Though not enough to alter these circumstances, these beaver dams did provide the only exception to this general feature of the landscape, and, in doing so, facilitated the formation of a truly unique habitat that has become essential to many species of this area.  Overtime, the industrious habits of these amphibious rodents have resulted in large, stagnant accumulations of snowmelt, flooding parts of the tundra for the entire summer.  This is just long enough for colonization of these areas by various species of marsh flowers, sedges, and shrubs, the last of which serves as the sole breeding habitat in this area for Lincoln's Sparrows.  The edges of these ponds also contain the only mudflats in the area, which provides critical feeding grounds for migrating shorebirds and resident species, most notably Bar-tailed Godwits.  Additionally, these ponds also allow several species of dabbling ducks, mostly American Wigeon, Green-winged Teal, and Northern Pintail, to breed in these hills.  Without beavers, none of these species, and probably hundreds of aquatic invertebrates that I'm missing, could possibly call the Nulato Hills home.

Marsh Marigold

American Wigeon

Definitively illustrating the pivotal role of beavers in this ecosystem was their absence this year.  For unknown reasons, possibly predation or trapping, not a single beaver was observed, and several of the dams confirmed the lack of sightings with unrepaired leaks.  As a result, water slowly flowed through these blemishes, leaving historical ponds reduced to small puddles -- so much so that few dabbling ducks were able to breed this year, a very different scenario compared to last year when beavers were common.


Untended dams result in...

...great access to to wildflowers!

With the arrival of summer, the focus of our work shifted from territory mapping and point counts to extensive behavioral observations and nest searching.  Nests of Bar-tailed Godwits, Pacific-golden Plovers, Whimbrels, Bristle-thighed Curlews, Savannah Sparrows, Lapland Longspurs, White-crowned Sparrows, Willow Ptarmigan, Short-eared Owl, and Long-tailed Jaeger were all found within the first week of June.  While nesting birds meant a void of courting behavior, it also meant the emergence of anti-predatory behavior.

Rough-legged Hawk, Northern Harrier, Short-eared Owl, Glaucous Gull, Parasitic Jaegar, and Red Fox are all potential nest predators of curlews and other large, ground-nesting shorebirds.  Luckily, however, most of these species were reasonably scarce (with the exception of harriers and fox).  Unfortunately, the sparse nature of these predators was over-compensated by increases in local populations of the most efficient nest predator of the land -- the Common Raven.  It is thought that recent increases in human populations in the surrounding villages and the subsequent expansion of landfills has facilitated the growth of raven populations, allowing them to venture into the tundra en masse


Common Raven in Bethel, AK

On a daily basis, the presence of a pair of ravens hunting low over the tundra was revealed by the cries of agitated Whimbrels, the fearless leaders of mixed shorebird squads devoted to preserving their genetic legacies.  Among these groups, Bristle-thighed Curlews, Bar-tailed Godwits, Hudsonian Godwits, and Long-tailed Jaegars were also present.  In fact, it has been suggested that these species intentionally nest near each other so as to reap the personal benefits of mob-attacks.  Indeed, previous research has suggested that curlews are particularly fond of nesting near Long-tailed Jaegars -- one of the most aggressive species in these flocks, yet not enough of a threat to curlew eggs or young.  As such, gathering data on species nesting near curlews was a top priority in the field, and all but one nest was within 100 meters of a jaeger nest (making curlew nest monitoring a very exhilarating event).

A well-observed trend that was noted was the different responses of Bristle-thighed Curlews and their closest relatives, Whimbrels, during these attacks.  While Whimbrels seemed to burst from the earth with an explosive energy, heading straight for the ravens with menacing clamor and dives, curlews tended to arrive on the scene last, where they generally trailed their squad mates at a considerable distance, rarely taking active dives at the adversaries.  However effective these efforts were at initially thwarting the advances of ravens, these cunning corvids almost always returned for multiple passes of the area, apparently testing the intensity of aggression from the angry parents, leading me to suspect that the illicited response to their presence was being used to find nests.  As testament to the genius of these birds, I must point out that we would later use the exact same method when searching for curlew nests.