Friday, August 30, 2013

Duluth's Common Nighthawk Migration

By Cory Ritter

Let's get real, Common Nighthawks are pretty awesome. They have striking plumage, make sweet peent calls, eat insects that may otherwise annoy us, fly erratically, and their apparently small bills open up to reveal a mouth resembling that of a muppet. Plus, they're the ABA 2013 Bird of the Year. What's not to like?

Duluth is a great place to watch Common Nighthawks during migration, and this year didn't disappoint. Last Wednesday, the 21st, Karl Bardon counted over thirty thousand Common Nighthawks—with the help of Dave Carman and others. However, that was just the peak, and the nighthawk migration continues.
Common Nighthawk in Flight
Common Nighthawk; Hawk Ridge Bird Observatory; St. Louis County, MN; 22 August 2013
Common Nighthawk Underside
Common Nighthawk; Hawk Ridge Bird Observatory; St. Louis County, MN; 22 August 2013
Common Nighthawk
Common Nighthawk; Hawk Ridge Bird Observatory; St. Louis County, MN; 27 August 2013
Common Nighthawk
Common Nighthawk; Hawk Ridge Bird Observatory; St. Louis County, MN; 27 August 2013

Wednesday, August 28, 2013

Jaegers at Wisconsin Point

By Cory Ritter

I'm back in Duluth for the fall hawk count season at Hawk Ridge, and I arrived a bit early so I could get some general birding in before my season starts. Some Parasitic Jaegers had been sighted a number of times from Wisconsin Point this month, and, since Jaegers are pretty sweet, I figured that would be a good place to check out. Karl Bardon and I headed over there last Friday, and the trip was a success. We had two light Parasitic Jaegers. This was of course in addition to the other regulars. We had some Ring-billed, Herring, and Bonaparte's Gulls, one Franklin's Gull, Bald Eagle, Green-winged Teal......anyway, the jaegers:
Wisconsin Point Jaeger From Below
Parasitic Jaeger; Wisconsin Point; Douglas County, WI; 23 August 2013
Parasitic Jaeger Underside
Parasitic Jaeger; Wisconsin Point; Douglas County, WI; 23 August 2013
Parasitic Jaeger in Superior Wisconsin
Parasitic Jaeger; Wisconsin Point; Douglas County, WI; 23 August 2013
Light Adult Parasitic Jaeger Upperwing
Parasitic Jaeger; Wisconsin Point; Douglas County, WI; 23 August 2013
Parasitic Jaeger
Parasitic Jaeger; Wisconsin Point; Douglas County, WI; 23 August 2013
Parasitic Jaeger in Flight
Parasitic Jaeger; Wisconsin Point; Douglas County, WI; 23 August 2013
Parasitic Jaeger Flight Feathers
Parasitic Jaeger; Wisconsin Point; Douglas County, WI; 23 August 2013

Sunday, August 25, 2013

Subalpine Hiking

By Cory DeStein

Currently there are nearly 11,000 acres of forest burning in the hills above Lolo, where I live in Montana. Before the blazes started up I was able to get some subalpine hiking in throughout the Bitterroots in Idaho.

I climbed nearly 1,000 feet on foot before reaching roughly 7,000 feet. The hike along the forestery roads was littered with Red Crossbills. Recordings obtained of the birds verified a majority as type 2 with a lone recording as type 5. White-crowned Sparrows were numerous along the hike along with Cassin's Finch, Brewer's Sparrow, Ruby-crowned Kinglets, American Three-toed Woodpecker, Williamson's Sapsucker and Gray Jays, with many of the sparrows scolding a pair of Townsend's Solitaire that swooped down the mountain.
Townsend's Solitaire
Cassin's Finch
At the top of the hike I birded a subalpine meadow where a family of Steller Jay's began scolding me as I ate lunch. My first and only warbler of the trip, a male Townsend's Warbler was drinking from a nearby creek before the loud scolding of the jays scared him off. I could hear multiple Clark's Nutcrackers calling from further up the mountain, but everything but the Steller's Jay went silent with a flyover Northern Goshawk.

Inbetween the scolding calls of the jays I began to pick up a new call, I was certain it wasn't a bird note, but it was brand new to me. Based off the habitat I was in, with some nearby boulders I climbed over to investigate. The calls continued to ring out from the rocks, and within 5 minutes I was rewarded with a lifer mammal, Pika! The small rodents whom do not hibernate gather grass through out the summer to feed on the hay during the winter. It was hard to get an idea of how many there were, but I had at least 3 with many calling from further along the ridge. Easily the cutest animal I have ever seen. Very cooperative subjects, except for the occasional Clark's Nutcracker spooking them.

Clark's Nutcracker

Ruby-crowned Kinglet

Elk cow with twins on the drive up the mountain.

Sunday, August 11, 2013

Photo Study: Red Crossbills of Clearwater National Forest

By Cory DeStein

With my first month in northwest Montana coming to a close, I am getting a pretty good feel for the local breeding birds in the area. I have been focusing quite a bit of time exploring a subalpine lake, Lily Lake at over 6,000 feet in the Clearwater National Forest, just over the border in Idaho. The forests surrounding the lake are dominated by subalpine fir along with, lodgepole pine, Englemann spruce, and Douglas fir. Clark's Nutcracker, Olive-sided Flycatcher, American Three-toed Woodpecker, Pine Grosbeak, Mountain Chickadee, Lincoln and Fox Sparrow. Greater and Lesser Yellowlegs, Solitary Sandpiper and Spotted Sandpiper have been observed feeding along the shore. And as with any lake in this region, moose are a frequent evening sight.
Cow moose and her calf at Lily Lake
Pine Grosbeak
Lincoln's Sparrow
Cassin's Finch
Lesser Yellowlegs
Perhaps the most numerous and cooperative bird at the lake is the Red Crossbill. My daily trips there are filled with birds feeding in the larches and gathering grit from the old campfire sites along the trail. I am working on gathering recording on what I suspect may be at least two types of RECR in the area. According to "Introduction to Differences in Crossbill Types" by Matt Young on eBird, there are as many as 9 "vocal types" of Red Crossbills in North America. I downloaded "Recorder the app" for iPhone, allowing me to export AIFF or MP3. An external microphone for the iPhone may be my next investment. I am working with a few people now to better understand using these recordings in call identification, but will keep you all updated on the progress! 

"Introduction to Difference in Crossbill Vocalization" by Matt Young

Friday, August 2, 2013

Yeah, yeah, it’s molting. So what…right?

Right guys?  Right?...Guys?... 

As the title implies a molting bird, in and of itself is not of much interest to a birder let alone anyone with any sense of natural history or levelheadedness.  The regular occurrence of the growing of new feathers is a simple fact of nature; a necessity for the physical laws of flight.  As feathers age, they become worn and brittle.  They no longer provide the bird with streamlining or the perfect airfoil wing-shape needed for dynamic flight, and instead produce extra turbulence and leave an otherwise healthy bird aeronautically indisposed.  So yes, the fact that feather molt evolved is interesting.  The physics of flight is interesting.  But a molting bird is just, well, a consequence of breaking though an amniotic eggshell with a horny, toothless beak.
A Mangrove Swallow visibly molting primaries.  The difference between the outer juvenile primaries (9 and 10) and the fresh basic plumage flight feathers is blatant.  Given that this bird is replacing very worn juvenile flight feathers, what age is this bird?  Try to use some of the information in this post to tell this bird's story.

So why is calling out or talking about a bird’s molt de rigueur amongst "good" birders?  What’s the freaking point? Yeah it’s inner primaries are shorter.  They’re growing.  It's outer primaries are browner.  They're old.  That’s what feathers inevitably do.  But can we learn something from a molting bird relative to, say, identifying or aging it?  Well, I am by no means an expert on molt, but I can tell you this: you can learn a lot about a bird from the timing and extent of its molt, from identifying its age, to distinguishing similar species in the field.  In these contexts, molt is both relevant to the average birder seeking to identify birds in the field, and to biologists (e.g. studying survivorship or reproductive success) looking at birds in the hand.  In some cases, being certain of a bird's age, sex, or species may be contingent on the timing and extent of its current molt.

We have touched on molt and especially with regards to molt limits (an outcome of molt) in the past, and bringing it up again merely stresses its importance.  I will not give you a detailed description of all molt cycles, stages, types, etc, nor the patterns or timing associated with specific families or groups of birds.  However, to start your own investigation of molt, it is helpful to get a little of the basics.  Molt, by definition, is the periodic growing of new feathers not the replacement of feathers.  Therefore anytime I refer to molting feathers, I do not mean feathers that are falling off, I refer to feathers that are growing.  
Here is an extreme example of a bird that critically needs to molt.  This Pigeon Guillemot's  remiges are worn to a point in which the feather shafts are all that remain.  This bird cannot fly, and chances are it cannot maneuver well underwater either since alcids use their wings to help them "fly" subsurface and catch food.  In fact we watched this bird for most of fall 2012 as it swam in the waters just off of Southeast Farallon Island.  The bird began molting quite late, but unfortunately never was able to finish.  The bird was eventually found dead on the island mid-molt.  Thus I imagine birds may often face the dilemma, molt or die.  Reason's why a bird might forgo molt include malnutrition, parasites, or disease among others.  I imagine this bird was struggling with at least one of these issues.
General Sequence for birds showing Complex Basic Strategy for molt (I suggest you read Howell's 2003 essays from Birding and his book, Molt in North American Birds, to really begin to understand the complexities in detail):

Pre-juvenal Molt (now referred to as first pre-basic, and includes all body and flight feathers, and is generally grown in the nest) --> Juvenal plumage (more often than not, much browner, streakier, and of poorer quality) --> Pre-formative Molt (generally within a few months of leaving the nest replacing most or all body feathers and no or some flight feathers) --> formative plumage (birds in this plumage are generally referred to as immature or "first year" rather than juvenal) --> pre-basic molt (the term definitive PB molt refers to the molt that results in the adult plumage: generally the following calendar year replacing all  feathers) --> basic plumage --> pre-basic molt (generally the following calender year all feathers)...

This molt pattern, in my opinion is the most important to get down.  Keep in mind that generally if you insert pre-alternate molts into the life cycle (complex alternate strategy) or remove the pre-formative (simple basic strategy) you have then pretty much addressed every species North American landbird.  Also keep in mind that, generally birds only have one complete molt (i.e. all feathers including flight feathers) per year.  So if we are looking at molting flight feathers, which is generally the case, we know it's probably a pre-basic molt or probably not a pre-formative molt (some exceptions to this rule).  This will almost never be pre-alternate molt (if ever?)
Knowledge of molt and their subsequent plumages can be helpful even in birds you've had no experience with.  This bird is bizarre in that during it's preformative molt, it replaced tertials, outer primaries, and the first secondary.  I had no experience with Garyish Saltators prior to this bird in my hand, but the contrast in colors resulting from two generations of feathers is glaringly obvious.  With no prior knowledge of how this species molts or looks as a juvenal, I can tell that the greener, worn feathers are juvenal (first basic).  Thus, the bird must be in formative plumage since during it's next basic molt (should happen soon) it should replace all flight feathers.  The eccentric molt seen here is further complicated by that middle replaced feather, but that may be a feather that was lost and replaced later (adventitious molt).  Keep in mind tropical birds may behave differently than their temperate counterparts. 
Here are some things to think about when looking at a bird showing flight-feather molt:

1) What time of year is it and where are you?  Birds typically molt their costly flight feathers after major life-cycle events like breeding or migration.  This is because many of these events require a lot of resources.  During the breeding season, birds put all their energy into creating and raising offspring. During migration birds put all their energy into...migrating.  So depending on when and where you are, molt can tell you something about a bird's age or even species.  For example, some species molt their feathers on the wintering grounds, some on the breeding grounds, and less commonly some during migration.  Knowing where species molt can sometimes help you rule out similar species.

I can think of two classic examples: 1) Jaegers molt on their wintering waters (I believe this to be universally true off the top of my head, but if anyone has a correction I would really like to know). During the fall in California, it may be possible to see all three jaegers in migration, but only Pomarine Jaeger winters along the CA coast. Therefore a molting jaeger in CA waters is almost certainly a Pomarine on its wintering grounds.  2) Similarly, most Empidonax flycatchers molt on the wintering grounds.  However, Hammond's Flycatcher molts on the breeding grounds.  Therefore any Empidonax with freshly molted plumage in fall in Western North America is likely Hammond's.  There are many other examples that I won't get into here (frankly I don't know a lot of it).  They include separating shorebirds in migration and winter, separating nighthawks in southern California (Common molts on the wintering grounds), and swallows in TX.

2) What feathers are molting? Tertials? Secondaries? Primaries? Coverts?  For example, it is very common for birds to molt tertials and secondary coverts, but no other wing and flight feathers during pre-formative molt. Thus you can generally age a bird in pre-formative molt as a hatching year.

3) What do other feathers in the wing look like compared to the feathers that are growing.  Are other feathers similar in color or much browner?  Browner, and often more tapered, feathers can often be attributed to juvenal plumage.  Feathers grown in the nest are grown rapidly and are of much poorer quality than adult feathers.  The difference is often quite clear, although not always.  The photo below shows very clearly three generations of feathers.)
Clay-colored Thrush with three generations of feathers in the wing.  The brown and very worn outer primaries and middle secondaries are retained juvenal feathers.  The olive green and moderately worn tertials (inner secondaries) were replaced during the pre-formative molt.  This bird was symmetrically molting the first few primaries and secondaries.  Notice how the juvenile feathers contrast in both color and wear with other feathers, but the formative feathers only contrast in wear (i.e. not color) to the brand new adult feathers.  Understanding the complex basic molt pattern (above) helped us to age this bird as a second year and understand the contrasts we were seeing in the wing.
4) What is the bird doing regarding it's life cycle?  Is the bird on it's breeding grounds? Is the bird on it's wintering grounds?  Is the bird migrating?  As I pointed out earlier, molting is energetically costly. As it turns out so is migration.  Interestingly, some species of birds have been identified as molt migrants, birds that molt at migration stopover sites.  Understanding where a bird molts has important implications for conservation.  Traditionally we like to think that looking at breeding and wintering grounds pretty much represents the whole picture.  If you protect those two areas, you are protecting the birds. Critically, however, molt stopover sites (e.g. Mono Lake for Wilson's Phalaropes and Eared Grebes) represent another consideration for successful conservation.

Practice looking at molt at your feeder in mid-late summer, and by taking or looking at photos.  Or by banding birds, but not everyone has that luxury.  While you're practicing, go back to that first photo of the Mangrove Swallow here.  Tell its story.  How old is it? Try to map out its life cycle thus far.