Sunday, October 4, 2015

Fall migration August-September 2015

Fall migration began on 1 August this year and we split our time between both our banding sites in the Punkhorn and on Wing Island, (our primary site) during the month. As I may have mentioned before, Punkhorn was our MAPS site from 2002-2009, a breeding bird survey so we only banded there once in every 10 day period from 31 May- 8 Aug.

 Our first week was spent at Punkhorn and we captured our first ever Blue-winged Warbler for this site, a  HY (hatch year) female. The females have more dusky lores and the crown color blends into the back.

Another Blue-winged Warbler was banded in Punk later in the month, a HY male this time- here is a picture for comparison. His lores are darker and his crown is bright yellow contrasting with the greener back.

We were able to age them as HY's because of the presence of a molt limit at the alula covert which they both replaced during their first prebasic molt. The color is a darker gray than the retained other alula feathers. We see this molt limit pattern in many different species of warblers in fall.

Ovenbirds, a species of warbler, thrive in the Punkhorn, due to the large acreage. They don't breed in areas under 50 acres, preferring contiguous forests and we hear them calling from all over our net sites. We have banded 67 so far this year so their populations are doing well. 

Northern Waterthrushes are an early migrant and we captured a very early one on 1 Aug. We usually band more towards the mid-end of August. Our totals for this year are 8 birds, normally we band 2 or 3.

We banded our first Eastern Phoebe of the fall on 6 Aug, a HY bird in full juvenal plumage with a yellow gape still evident. Surprisingly we have never banded one in Punkhorn even though they breed around the house near our nets on a regular basis. This year we were amazed at the tenacity of a mother phoebe who built her nest in the generator house right above it on the light and remained on her nest even when the generator was turned on!
It seems phoebes disperse early after fledging and move to more productive stopover sites like Wing Island where we band many in the fall.

On 19 Aug we banded another young bird, a Pine Warbler, so different looking from the parent in coloration.

The drab brown on the back and buff breast differs dramatically from the adult she will come to resemble by next spring (if she is a she!!).

We caught a very old Black-and-White Warbler, at least in his 10th year since we know he was born on or before 2006. You may notice some black flecking on his throat.

Here is a HY male banded on 29 September for comparison. The young male has lighter lores, white throat, and grayer auricular area.

House Wrens are easy to age before their first prebasic molt because the barring on their feathers line up in a row.

I am so fortunate this year to have a lovely person, Donna Kucia, to enter all my data into our excel spreadsheet. Normally I am frantically putting it all in during November and December to get my data in before the end of the year. She rarely misses a day and enters data while the rest of us are banding. I banded a hummingbird on the 25th and allowed her to release it- she was thrilled!

Due to the difficulty of separating the plumage of Alder Flycatchers (ALFL) from Willow Flycatchers (WIFL) even in the hand, they are often referred to as Traill's Flycatchers (TRFL), unless you hear them vocalize. However, there are banders who band these birds on their breeding grounds and have offered some different tips on distinguishing one from another.  

On 8 August a young Alder Flycatcher (ALFL)was banded in the same net area where I had previously banded both a male and female with a brood patch. Before capturing I could hear ALFL "pips" and whistles. I have learned from another bander who bands many ALFL's that they will whine in the hand and this bird was no exception. He also said that WIFL's are mostly silent in the hand. The same is true for Purple/House Finches. What was really odd about this bird was it still had the head of a large ant stuck by the pincers in his mouth! I relieved him of his burden before flying off. It reminded me of the time when my oldest son at the age of about 10 developed a fondness for eating bugs (just a phase when he was practicing survival skills) and ate an ant that promptly hung on for dear life on his uvula! We thought maybe the fizziness of Coke would cause the ant to let go, but no, I had to resort to taking it off with tweezers piece by piece, very gross! 

The crown of an ALFL tends to be more angled than WIFL. Below is a probable WIFL captured on Wing Island on 16 Sep (this bird was silent in the hand).

and possible ALFL from the 13th.  While ALFL's tend to have more distinct eye rings and lores, there is so much variation in plumage that with the exception of the birds in Punkhorn I heard vocalizing, these birds will be reported as TRFL's to the Bird Banding Laboratory.

The head of the ALFL is a bit darker than the back showing more of a contrast.

The head and back of the WIFL blend together.

One thing I've noticed about banding in both places is that Punkhorn is a great spring site as it is shielded from the winds and being in a swamp, there are typically more insects around. Wing Island is more exposed to the elements being right on Cape Cod Bay. Punk is also a great place to raise young, with plenty of summer berries and a huge tract of land. But come August most of the birds disperse from there to places like Wing Island with fall berry crops to fill up before heading south. Since we were getting so few birds I decided to spend most of our time on Wing Island unless the winds were too strong. I also kept my fingers crossed that the foxes moved on and thankfully we haven't had an issue this fall. It is so nice to be back on Wing where we can watch the sun rise!

Wing Island is an important stopover site for many migrants and it is always thrilling to see what species we will catch with Yellow-breasted Chats being one of my favorites! Below is a HY male with very dark lores, 

compared to a female banded on 25 Sep with gray lores.

They are easy to age with a molt limit usually seen between the darker replaced primary feathers (white arrow) and browner retained juvenal feathers. 

The 5th brought in our first of two Warbling Vireos with their indistinct facial pattern 

and we banded 6 Philadelphia Vireos (a record for us in one day) on the 18th.

The 10th primary feather (white arrow) is longer than the primary coverts of Warbling Vireos

 but reduced in Philadelphia Vireos

We lost a whole week of banding the 2nd week of September due to the very hot and extremely humid weather. With temps in the 80's and humidity reaching 100%, those nets in the sun can be extremely dangerous for any bird caught. So I err on the side of caution and waited until the weather turned. On the 13th we returned and were rewarded with some nice species including a beautiful Canada Warbler,

Nashville Warbler,

Prairie Warbler,

and an interesting HY male Yellow-shafted Flicker, showing both red and yellow shafts in the wing. 

While many birders in our area would consider this an intergrade between a Red-shafted and Yellow-shafted Flicker, the more plausible explanation is the bird feasted on berries containing a substance with more carotenoid pigments (causing red hues)  during the time those feathers were growing in. HY woodpeckers will replace their primaries during their first prebasic molt but not their corresponding primary coverts.

Additional birds banded this week include an Indigo Bunting, HY female, with brown-edged feathers,

Wilson's Warblers (HY male,note yellow-edged black feathers on black cap indicating HY)

 and female WIWA with barely any cap.

We banded a female HY American Redstart on the 15th. She has a very pale yellow area on the side of her breast

compared with the male with more orange-yellow coloration, whom we banded on the 24th. Also notice the black flecking in the face and breast.

His rump feathers are very black; in the female the uppertail coverts are more gray blending in with the back.

Also on the 15th was our first Blackpoll Warbler of the fall this year

and a very young catbird (sorry the pic is so dark), so you can see how late these birds produce young. This one was still growing in the juvenal feathers and was brought right back to where we captured it after banding.

Banders often encounter the strangest things on birds. On the 18th we captured a very interesting catbird,a HY that had already finished his molt.

But when I went to put a band on the leg I saw there was an extra claw! 

Also on this day was a Black-throated Green Warbler,

a Magnolia Warbler, 

and my favorite bird of the day, a Mourning Warbler. No, this species doesn't have spiked feathers on the back of the head, I just forgot to take the picture before skulling!  

What is skulling you ask? When baby birds are born they have just one layer of skull and as they age they put a second layer down below the first connected by columns. We can wet the head and actually see this process by noticing the pink first layer and the outline of the second layer by tiny white dots. This is a gradual process that happens through fall and is one of the ways we age birds along with molt limits or a lack of one. Most complete this process by October/November.

We had our earliest ever for fall Ruby-crowned Kinglet, a HY female, on 20 Sep,

and a Veery on the 22nd. 

A young man who has helped me with banding in the past, Keenan Yakola, processed many hummingbirds during his time spent in Peru but never banded any, so I helped him with banding his first hummingbird, a HY male.


This is what he looked like with just a couple of red gorget feathers (not the same bird).

The last week of September brought in more nice birds such as this later migrating warbler, a Western Palm Warbler,

a female White-breasted Nuthatch (a local resident), 

three beautiful Blue-headed Vireos,all on the 29th,

and our first ever for fall, Worm-eating Warbler on the 25th!
This bird was aged as a HY due to the presence of rusty tipping on the tertials (white arrow) similar to what we see in waterthrushes.

Many thanks to all who helped out during the first half of our fall season. Our volunteers donated over 600 hours and are so necessary to the function of this station. Plus I just love teaching new people the fine art of ageing birds! In order of hours donated: Donna Kucia, Gretchen Putonen, Claire Revekant, Col Lazeau, Robert Finer, Bradford Bower, Judith Bruce, Ronald Kielb, Christina Baal, Carrie Hisaoka, Maddie Nobili, and numerous others who came for a morning.