Monday, October 11, 2021

WINGS Tour of Peru: Rainforest Lodges of the Madre de Dios

I’ve been home just two days from my two wonderful tours to southeastern Peru, and I while I was excited to see how my garden has progressed (or aged, as the case may be) as fall approaches, I was also not quite ready to leave Peru. I wish I had had just a few more days to explore more trails and squeeze out a few more species. The rainy season was just barely starting, and plants were beginning bloom, birds were nesting, and more insects were emerging.

My second tour visits two rainforest lodges of the department Madre de Dios. It was an abrupt but delightful change of pace from the first Peru tour, where we had been mostly in mountains of the neighboring department of Cusco. For one, it was warm and humid, though on two days we were under the influence of a late cold front, when the overcast skies and cooler temperatures were quite welcome.

The tour ended with an impressive total of about 375 species of birds. And though no one took part in both tours, my 20-day total came to about 650 species. This second tour was supposed to have six participants, just like the first one, but for various reasons, four of the participants canceled, leaving just two – my friends Dana Gardner and Michael Chinn from Berkeley, California. So this was much more like a private tour with friends than a regular WINGS tour, and I think we all benefitted from the flexibility that entailed.

Unlike the first tour, which involved a fair amount of driving, we walked every day, piling on the miles, but one of the most enjoyable aspects of this tour is being able to bird right outside our rooms. A surprise for me here was that two of the cabins had been completely dismantled. A few feet of the overlook had sloughed off in June, and it was deemed that these two cabins were too close to edge in the event that an even larger chunk of earth might collapse.

We were walking by our cabins one morning when we heard a ruckus from inside a dead, hollowed-out palm trunk, and we looked up to see this Tawny-bellied Screech-Owl indignantly poking its head out of the top.

Another treat was walking the same trails on multiple days – and discovering how different they can be from one day to the next. On our first pass by a large tree dropping red fruits to the ground, a group of Pale-winged Trumpeters approached and put on quite a show. The next time we passed there, a stunning Plum-throated Cotinga sat just under the canopy for extended views. This is the fruit of Pseudolmedia laevis in Moraceae that attracted so many birds.

And on a third visit we flushed a Ruddy Quail-Dove off its nest with two eggs, right next to a stunning cannonball tree (Couroupita guianensis) that was dropping its flowers all around the tree.


And yet on another pass on the same trail, this female Cream-colored Woodpecker perched at eye-level very close to the trail and sat there for an extended time, seemingly unafraid of our presence.

We birded one of the closer trails to the lodge several times in search of its bamboo specialties, and we were surprised on one morning by a pair of very quiet Rufous-capped Nunlets low in the vegetation right off the trail.

Then again there were some reliable birds, such as the lek of Band-tailed Manakins which showed well when we stood still near their favorite display area, and on our second stop they were even more cooperative. Or the pair of Great Jacamars that we found along the same stretch of one trail on several days. We suspected they might have had a nest nearby.

One surprise at Los Amigos was a rare Brown-banded Puffbird that flew in quietly while we were scanning the canopy for a singing Western Striolated-Puffbird (which we ended up seeing on another day). This was my first for Peru.

Another was the scarce and very unpredictable Amazonian Parrotlet, which if found is usually just a quick-flying flock through the canopy. This year we saw pairs and multiple small flocks on five days, perched in trees and feeding right over the trails, offering great views of this bird that Don Stap wrote about in his popular book A Parrot Without a Name. Here are two in a fruting Guazuma crinita tree, apparently one of their preferred foods.

The last days of birding at Tambo Blanquillo Lodge were a nice change of pace, starting with a long boat ride to get there on the Madre de Dios river. We spent most of a morning at their famous clay lick. It was a thrill to see a flock of about a hundred Red-and-green Macaws take off in a deafening flight. They never did come down to feed on the dirt, but many other species did, including this collection of Blue-headed, Orange-cheeked, and Mealy parrots.

We had a delightful paddle around one of the oxbow lakes, where a Pale-eyed Blackbird finally appeared.

We also saw dozens of Hoatzins, Greater Anis, and a Sungrebe, and many other species presented themselves. A favorite bird of the tour and a very lucky find was this lone Green-and-rufous Kingfisher, perched typically in the deep shade of the overhanging vegetation.


We also saw a fantastic variety of butterflies and other insects, frogs, and mammals, including nine species of monkey, many in abundance. Along one trail we looked up into a tree cavity only to see this sac-winged bat scramble out and perch in plain sight on the trunk.

The station science coordinator at Los Amigos was very generous with his time, and he showed us this White-lined Leaf Frog that had been roosting on the same leaf for a few days right by the office; here it is in the evening setting off to forage.

Of the many insects I photographed, this long-horned beetle Discopus spectabilis (identified for me by iNaturalist user chickenparmesan24) was one of my favorites.




Monday, October 4, 2021

Back in the Saddle Again: Birding and Natural History of SE Peru 1

I’m leading my first international tours since the start of the pandemic, and everything is going exceedingly well. The first tour just finished a week ago, where we visited the Machu Picchu and the Manu-Kosñipata road, all in the department of Cusco. Some of the lodges and hotels were running with a much-reduced staff, still rebuilding since opening back up to international tourists in July, but you wouldn’t have known it. Clean rooms, excellent meals, and well-maintained trails greeted us at every stop.

We hit the ground running with a full day in the high wetlands near Cusco and superb birding in the Sacred Valley, where a hummingbird feeding station with Giant Hummingbird, Shining Sunbeam, Black-tailed Trainbearer, and Tyrian and Scaled Metaltails was a highlight. We ended the day with this Peruvian Pygmy-Owl, which came in cooperatively for a tour first.


The ruins of Machu Picchu were as fabulous as they promise to be, and while there we had a very close encounter with a pair of the lovely Inca Wren as we climbed through the bamboo to the upper platforms and their magnificent views.


We then birded the forests along the Urubamba River and had wonderful views of this gorgeous Masked Fruiteater.


After birding the dry, rain-shadow side of the mountains north of Cusco, where we saw Mourning Sierra-Finch, White-winged Cinclodes, and Streak-backed Canastero, we dropped down through the moist cloud forests to Wayqecha Biological Station with its enchanting view of hillsides in all directions covered by pristine montane forests. We saw most of the specialties here, including a pair of Urubamba Antpittas at close range in the dark mossy understory. This Yungas Pygmy-Owl and this ridiculously fearless Puna Thistletail just down the road were among many other wonderful birds we saw here.



One of the most exciting sightings of the tour was a mammal in the higher cloud forests at 2000 m elevation. We were in touch with a couple of regular WINGS clients who happened to be on a totally separate tour just a week ahead of us, and they spotted what turns out to be Brown’s Toró clambering into its mossy nest, a caviomorph rodent (that is, related to the guinea pig, capybara, agouti, spiny-rats, and not closely related to rats). What was most amazing is that this species was discovered only in 1999 (described in 2006), and the only evidence of its existence until this week was the lone type specimen in the Lima museum. We hope that some more details of its natural history can be learned from this amazing find.


Among the highlights at our mid-elevation stop were the Andean Cock-of-the-rock lek, Peruvian Piedtail at garden flowers, a pair of Squirrel Cuckoos on the roadside (one carrying a praying mantis back to their nest), a kettle of 87 Swallow-tailed Kites taking off from their night roost and heading south to winter in Bolivia and Brazil, and this male Versicolored Barbet accompanied by a female Silver-beaked Tanager at the lodge’s feeders.


Our last birding lodge was Villa Carmen, where an explosion of tropical diversity greeted us, and the soundscape of so many birds singing was almost overwhelming. We saw over 100 species before lunch each day, with a glowing male Band-tailed Manakin getting the most votes for most memorable bird of the tour. Chestnut-capped Puffbird, Rufous-capped Nunlet, Tawny-bellied Screech-Owl (nesting down in the top of a small, dead palm stem behind cabin 3), multiple Bluish-fronted Jacamars, Blue-throated Piping-Guan (with it’s amazing rattling wing display), Gray-cowled Wood-Rail in the trail almost at arm’s length, and this ear-piercing Red-throated Caracara putting on a show were just a few of the favorite sightings.


Two new hummingbird feeding stations just up the road from Villa Carmen really filled out our birding list, one of them hosting 18 species at the feeder, including this amazing male Rufous-crested Coquette. A bonus there was Buff-tailed Sicklebill that came to its favorite heliconia that was growing off to the side of the garden.

Finally, among the exciting non-bird highlights were the amazing butterflies we saw everywhere. This minute metalmark Syrmatia lamia on our first morning at Villa Carmen was special, as this rarely seen species represents the first sighting in the entire Manu region, the most diverse area in the world for butterflies and also one of the most thoroughly sampled regions anywhere.


I’m now heading onward for our Jungle Lodges of the Madre de Dios tour, where more fabulous birding and natural history experiences await us.


Tuesday, July 27, 2021

A Gambel's White-crowned Sparrow Irruption


This blog isn’t dead yet – I’m still here and do have lots to share. I have much that I could have been blogging about these past three months – so much that the idea of catching up seems too overwhelming a task to even start on. But here I am, and I can’t let the amazing White-crowned Sparrow migration I witnessed in the yard this past spring go undocumented.

I’ll briefly review the subspecies of White-crowned Sparrows we have in Oregon and then share some photos from the phenomenal migration of Gambel’s White-crowned Sparrows that birders experienced in western Oregon in mid-April this year. It would be nice to at least to have a written record of what transpired on my blog, since it seems to have been a rather rare event, with essentially nothing published of this phenomenon, at least in the literature covering Oregon ornithology and in the available species accounts of White-crowned Sparrow.

In Oregon we have three distinct subspecies of White-crowned Sparrow.

1. Zonotrichia leucophrys pugetensis is the population that breeds in western Oregon, from just east of the Cascade crest to the coast, and much of the population is either sedentary or short-distance migrants. Presumably those that breed at the highest elevations migrate the farthest, and our resident birds are augmented by some wintering here from farther north. Apart from the voice, a pale yellow bill and dull blackish back stripes separated by buffy stripes are characteristic of this subspecies.
This pugetensis White-crowned Sparrow was at Cape Meares on the Oregon coast where a common breeder.

2. Zonotrichia leucophrys oriantha breeds in scattered brushy mountain meadows east of the Cascades. This entire population is migratory and winters mostly in northwestern Mexico, with occasional individuals in southeastern Arizona. The black lores and reddish bill are more like the nominate subspecies of eastern North America.
This oriantha White-crowned Sparrow was at Yellowstone National Park, where they breed.

3. Zonotrichia leucophrys gambelii is the widespread breeder in the high arctic regions of NW North America and is essentially entirely migratory, mostly wintering in eastern Washington and Oregon south to NW Mexico. It’s the abundant wintering subspecies in the SW United States. Its bill is an orangey yellow, and the dark back stripes have a reddish hue, with the pale stripes being grayish white.
A migrant gambelii White-crowned Sparrow where it is an expected migrant near Lakeview, Oregon.


Very much like the winter of 2019-2020, this past winter I had two or three White-crowned Sparrows of the locally and regionally breeding subspecies Z. l. pugetensis in the yard as part of the winter flock of passerines. They used the brush pile for cover and took advantage of my practice of scattering bird seed on the ground all around the yard. This species is not common nor unexpected in suburban Eugene, though if you go just outside town to slightly more rural areas, winter flocks will have dozens of them. These are essentially all Z. l. pugetensis, which also breeds throughout most of western Oregon (especially in brushy areas on the coast and in clearcuts in mountains), and there is some regional migratory movement that is little understood. If you go back just a couple blogs, you’ll see where I documented that a Canadian bird was passing through here at the end of March, presumably wintering somewhere not far south of here and heading back to breed in southwesternmost Canada.

These are photos of a first winter and an adult pugetensis that wintered in the yard.

Note the pale yellow bill and blackish back stripes.

Suddenly on April 13, there was a huge increase in White-crowned Sparrows at my brush pile, rising to 24 total birds on April 15 and 16, and continuing for a couple of weeks in decreasing numbers before the last ones departed by April 30. It turns out all these new birds were the high-arctic breeding subspecies Z. l. gambelii. I got many photos of them and recorded their distinctive songs several times. It’s worth noting here that a year ago, while I was paying very close attention to bird movements in the yard and neighborhood, there was no such influx of migrant White-crowned Sparrows. In any event, it was that song, instantly transporting me back to my back yard in Tucson, that clued me in.
The first five notes of George Lloyd's Symphony No. 5
https://www.youtube.com/watch?v=XqBsMfn8fy8

The actual status of Z. l. gambelii in western Oregon is poorly known, though the references I checked  (albeit dizzyingly circular) simply state that it’s the common migrant east of the Cascades and less common west of the Cascades. It seems the only published evidence of their presence in western Oregon  is a mention of a late April specimen (“and at other dates”) from a collector Portland in the late 1920’s. Since then, it seems little has been done to document this subspecies. Recent eBird submissions do show that that they occur from time to time, but when exactly, how many, how often, and under what circumstances? Unfortunately, the lack of awareness and apathy from birders who can’t count it as a species on their lifelists has resulted in few attempts to document the status of what actually may be a perfectly legitimate species.
This gambelii White-crowned Sparrow in my yard shows the orangey bill, and the often brighter and broader white head stripes are apparent.

One of the 24 or so gambelii White-crowned Sparrows in my yard. In this light the reddish brown streaks on the back are very obvious.

I’m an ear birder with a notoriously poor visual memory, so my mental map of the various White-crowned Sparrow subspecies (and their dialects — maybe the subject of a later blog but perhaps too complicated…) is based on their songs. I grew up in western Oregon becoming very familiar with the classis pugetensis song of “Teeew, titit-ti-tieew, titititi,” with some variation on the ending. Then I spent some years (decades) living in Arizona where gambelii dominates as a migrant and winter bird, joined by birds of the interior breeding oriantha in migration and occasionally in winter. Birding Colorado, Utah, and SE Oregon in summers familiarized me with the visually distinctive oriantha birds, but it was always their distinctive song that struck me.

In Arizona, the abundant wintering White-crowned Sparrows, numbering into the 1000’s on a good day, were 99% gambelii. In the growing daylengths of the early year, the males would practice their song, and there was little variation. I’ve always likened it to the first five notes of George Lloyd’s Symphony No. 5. (It might be a relatively obscure piece of music, but it’s apparently his most famous work and worth knowing. I think of it as a mix of Gershwin’s Rhapsody in Blue with Holst’s The Planets, maybe with a bit of Bernstein’s West Side Story thrown in.) It was a common sound in my Tucson back yard.

I moved back to Oregon finally in September 2019, back into the land of our reliable resident, year-round pugetensis, and their song familiar from my youth. That’s all I saw here until I led my Oregon in Late Summer tour for WINGS in early September 2020, and we saw an abundance of southbound migrant gambelii as soon as we reached the central Oregon lava lands and Great Basin sagebrush steppe. I didn’t try to discern them using any possible field marks, going on the common knowledge that migrant White-crowned Sparrows east of the Cascade crest are all gambelii. And that’s still the apparent truth.

On October 24, 2020, while I was birding the Philomath Sewage Ponds about an hour north of where I live, I was watching the sparrows coming to a known seed drop, and I heard the obvious five notes of Lloyd’s Symphony No. 5, saw the bird, and took some photos, thinking maybe these will prove to be distinctive, should I ever try to find the time to tell the subspecies apart visually. In any event, that was the first time I had knowingly heard Gambel’s White-crowned Sparrow in western Oregon. This is my best photo of that bird. I can now see in the photos that the more orangey bill and reddish stripes to the back are quite noticeable. From looking at eBird submissions, it appears that this bird actually spent the winter here.

We had some very unusual weather here this spring (though there aren’t many on planet who couldn’t say the same thing these days). In early April just before these stray Gambel’s White-crowneds showed up, we had several days of persistent north and northeast winds and clear skies. Throughout the month we had drier weather (the driest April on record, in fact), colder nights, and warmer days than usual. It seems that these sparrows normally migrate only east of the mountains, and that makes sense considering that they’re coming from winter grounds in inland areas south and east of here and are returning to inland Arctic areas to breed. A route west of the Cascades would direct any northbound migrants along the coast and to Pacific forests of SW Canada and SE Alaska, not the interior Arctic. This is the route taken by our abundant migrant Russet-backed Swainson’s Thrushes and chryseola Wilson’s Warblers, for example.

So my guess is that this spring the unusual weather patterns, specifically the strong winds from the NE at the crucial altitude, led these sparrows to stray west of the Cascades. But if that is indeed the answer it only brings up more questions. If we were to have the exact same weather pattern next year, would we also see Gambel’s White-crowned on the west side? Or does it only happen in years with a bigger than normal winter population moving back north? How often does this happen? I’d love to keep track next year, but I’ll be leading my Jamaica tour in the middle of that same time frame. And I hope that a greater awareness will also result in more birders paying attention, documenting their sightings, and submitting their sightings to eBird.

This Cooper’s Hawk, one of our resident neighborhood pair, took note of the sudden influx of sparrows and spent several days in the yard, though it wasn’t very successful at catching any of them.




Monday, April 12, 2021

Answer to Sound Quiz

The Sound Quiz I posted the day before yesterday is a Purple Finch.

This was given by an adult male Purple Finch, which had been perched next to the female, and both were giving call notes. The female flew to a tree about 20 meters away, and the male then began a series of soft call notes and subsongs. The subsong is often just a softened version of the long song, incorporating just a bit of mimicry, so I thought this one was unusual in being rather loud and having no Purple Finch sounds at all.

Twelve species were mentioned in the answers I received from my post to Oregon Birders On Line, and the top guess was Ruby-crowned Kinglet, which I found interesting. That species has a ridiculously complex song of very similar length and pitch, but it has only limited variety based on a set of three elements. Once you know those elements well, this song doesn’t sound like a Ruby-crown any more.

Observers who realized that mimicry was involved immediately thought of Lesser Goldfinch, which makes sense, as it is our most notorious mimic. Lesser Goldfinch incorporates many other species’ calls and song bits in its normal long song, and it does so many, so fast, your brain can’t quite keep up. Once you’ve recognized Violet-green Swallow and American Robin call notes and thought “wow”, it’s already gone on and mimicked five other species. But when it does this, the song is several seconds long and also incorporates many stereotypical Lesser Goldfinch sounds.

This quiz bird’s song is 100% mimicry though. This song differs from a mimicry-packed Lesser Goldfinch song in being only 2.5 seconds long and is not interspersed any goldfinch calls. It’s also a bit lower pitched than a typical Lesser Goldfinch song, and though it might be indistinguishable from the same song type given by a Cassin’s Finch, this was recorded in my Eugene backyard, where Cassin’s Finch doesn’t occur. Mimicry in House Finches seems to be rare or even undocumented.

The full recording starting with call notes, and unfiltered traffic noise can be heard here:

The one song phrase I used in the quiz is the last one at 2:30. Here’s a screen shot of the sonogram that I marked up using Preview.


I interpret there to be eight mimicked elements smashed together. The first is Northern Flicker, and the next two are both different call types of American Robin. The fourth I figured is the rattle call of Hairy Woodpecker. I had originally thought it was a close match for the fast rattle of White-headed Woodpecker, but I’ve since determined that that recording in my library is a mislabeled Hairy.

The next element is a rapid buzz, which I think might be Dark-eyed Junco or maybe Pine Siskin. Then there is one slurred note that is too fragmentary for me to place; and it might actually be a continuation of the previous element.

The next-to-last element is two notes that only when hearing them in complete isolation can you realize that they are Barn Swallow. Finally, the last element is a perfect Hutton’s Vireo.

To illustrate the last two, I created phony recordings by copying and pasting these same elements into a rhythm that might be heard in nature. When done this way, the mimicked species becomes more obvious. 

Saturday, April 10, 2021

A Song Quiz

I posted this song quiz to Oregon Birders Online, and it's been fun to see how different people hear it. I'll add the ID and my analysis tomorrow.

I recorded it in my Eugene back yard on the morning of March 30 and saw the bird, so I know what it is.



A Visitor from Canada in the Brush Pile


On the bright and frosty morning of March 30, I spotted what is quite likely the most unusual bird I have seen in my yard so far (having lived here in north Eugene for a year and seven months). The only real rarities I’ve had so far have been Lark Sparrow (a common bird only in eastern and far SW Oregon), and a Yellow-bellied Sapsucker (a state-wide vagrant that was a one-day wonder). No, this bird wasn’t a vagrant, though it was much rarer than either of those two: it was the White-crowned Sparrow pictured above, and while this species doesn’t usually strike one as being out of the ordinary, I draw your attention to its right leg.

I nearly shrieked out loud when I saw it. I’m not really well-connected to the bird banding community, though I enjoy banding and have personally banded several hundred birds (including over 500 in one single, insane morning on an islet in Germany’s Baltic Sea 24 years ago). But I am fairly confident that no one is banding in my immediate neighborhood. And I’m quite aware of how rare and exciting the random sighting is of a banded bird in the wild, especially a passerine. This bird was present all this day and the next, and I snapped over 700 photos in the first few minutes. Fortunately, this bird was unafraid of my presence as I sat comfortably on my deck chair while it scratched around my brush pile, foraging on seed that I frequently scatter on the ground. The band was loose enough that it moved around, and the sun was bright enough that I was able to get a fast shutter speed, and I also knew to underexpose the shot by at least two full stops in order to not “burn” the image of the reflective band.

Out of all of those images, I needed no more than three in just the right poses to be able read the entire nine-digit number. I entered the data on the USGS website https://www.pwrc.usgs.gov/bbl/bblretrv/, and instantaneously I had an automated response:

INFORMATION FROM OUR FILES:
Species: Puget Sound White-crowned Sparrow
Date banded: 04/20/2018
Banding Location: NEAR RICHMOND, BRITISH COLUMBIA, CANADA
Age: HATCHED IN 2016 OR EARLIER
Sex: UNKNOWN

Richmond is a southern suburb of Vancouver, and the age of the bird at the time of banding shows that it will be at least five years old this summer. I’ve been watching the brush pile assiduously all winter, and especially in the past week inspecting the leg of every bird, and it’s definitely a new bird as of March 30 and was here just two days. I’ve been hoping to receive an email directly from the bander, as surely they’re at least as excited as I am to have such an amazing band recovery. They must have received the same automatic email that I did, and they would probably be the only one who might have answers to the many questions that this sighting leads to. The only question that this sighting answers is “do any of the White-crowned Sparrows we see here in March come from Canada?” But I wonder where this bird spent the winter. I wonder where it was going to. Does it return to the area where it was banded every year? Are there other sightings of this same bird? Have other banded White-crowned Sparrows from this part of BC been spotted elsewhere? Unfortunately, the USGS reply doesn’t tell me who banded it, and eleven days later, I’ve heard nothing. I'll post here should I receive any news.

Spring has sprung, and birds are on the move, and seeing the changes is fun. I’ve had just two immature White-crowned Sparrows all winter, and one had started molting in the black into the brown head stripes well before the other. Starting a few weeks ago, they were joined by an adult every few days. Finally, as of today I have three adults and one immature; one of the adult-plumaged birds is probably the more advanced immature that I slowly watched molt in, while the same lagging immature was here until about two days ago.


And also suddenly as of April 8, there is a new adult in the yard, a very loudly and persistently singing bird that has the classic NW Oregon pugetensis dialect.

I’ve had one Lincoln’s Sparrow call the brush pile home all winter. Suddenly on March 4 it was joined by a second bird, though they don’t tolerate each other’s presence in the same brush pile for long. As of this morning, at least one is still here.

I had a single Fox Sparrow all winter too. A second bird popped in briefly and wasn’t tolerated on March 12, then March 28 was the last I saw of my winter bird. A single Song Sparrow has been here as well every day, last on April 3. It did not like the Lincoln’s Sparrow, and it also regularly chased only one of the White-crowned Sparrows.

Eleven Golden-crowned Sparrows rounded out the brush pile flock all winter, but there’s changeover there too. I now have five, and since I didn’t notice much molting going on, it’s quite possible that the five stunning alpha-like adults now are totally new birds, while the immatures all moved on to molt farther north.

And it’s also a bit sad to see the Dark-eyed Juncos move on to breed in more forested habitats. I had over 40 all winter, though they don’t mind forging in the open and were much less bound to the brush pile. There are fewer than 10 left this morning, and while I’ll miss them, they’ll be back soon enough next fall, and I won’t miss the chore of scattering seed for them all over the yard. This "cassiar" junco has been here all winter. It's like a Slate-colored with a more contrasting dark hood.

I like to say I won’t miss the Pine Siskins. There are still over 40 in the yard this morning, and they are swine, shoveling food out of the feeders and edging out the shier American and Lesser Goldfinches. But their presence and sounds are cheerful, and I’ve enjoyed hearing all the species they mimic in their jumbled song. The other day I recorded one doing a very good Olive-sided Flycatcher.

March also saw a lot of movement of Red-tailed Hawks and Bald Eagles, but overhead, not in the brush pile. Only once did I see them in the same patch of sky, and the frisky hawk decided to harass an eagle.


Monday, March 22, 2021

Nocturnal Duck Commutes: Is a Flying Duck a Sitting Duck?

I think I’ve finally solved a huge mystery that has been bugging me for nearly a year. The very foundation of the scientific world is shaking, and the journal Nature is begging to publish my earthshattering discovery: Lesser Scaup, American Wigeon, and other ducks are commuting in the dark between the Willamette River and Fern Ridge Reservoir twice each day, and their route takes them directly over my house.

Ok, I was being facetious. I know full well that no one in the world cares, and that this is only barely worth blogging. And though my neighbors are nodding in a polite way of wanting to share in my excitement, I actually feel like I’ve cracked the DaVinci code here. Such are the simple pleasures during a year of quarantine.

The whole intrigue actually started well over a year ago, when my next-door neighbors’ son Thomas was visiting between seasonal birding and natural history jobs (yes, I’m envious). He texted me at dusk as he was jogging just a block away and saw a Barred Owl fly right towards our houses. I looked at the text maybe a minute too late but ran outside anyway, and of course I never saw the bird. That sighting, plus Thomas’s having seen a Barred Owl in their yard a few years ago when he was in high school, started my habit of having an evening glass of wine or herbal tea up on the carport roof, hoping to see or even hear an owl as it slowly got dark. I probably gave it up after a few days, but I sporadically continued my vigils over the next several weeks when it wasn’t raining, and in early April a year ago, I saw 11 ducks zip by right at dark, headed west-northwest. Over the next few days I noticed a pattern of this late evening fly-by, and at one point was confident enough only to call one bird an “Aythya sp.”, meaning it was either Lesser Scaup or Ring-necked Duck (both common here), but it was just too fast and and there wasn’t enough light to see details. A few days later I got good views of a pair of Hooded Mergansers making the same fly-by. But until now, “Aythya sp.” has been a dirty mark on my yard list. It has counted as a species, because I had not identified any other member of that genus to species.

Barred Owl from Tillamook County, Oregon. I'm still waiting to add this to my yard list.

This winter I’ve become a more regular fan of sitting out on the back or front deck as it gets dark, still hoping for a Barred Owl. And I noticed that every night, about 20 minutes after official sunset, a total of about 18-35 smallish, fast, diving ducks would fly over in 3-4 small groups. All were headed in exactly the same direction, and it was a nightly thing. The birds I was seeing each dusk were consistent with Lesser Scaup – not tiny like Bufflehead, and not long-billed like mergansers – but I couldn't be sure they weren't Ring-necked Ducks. Finally, one evening I got a longer and better view of the commuting ducks on one of their earlier arrivals, and I was convinced they were Lesser Scaup.

Dusk Vigil from my front deck

At about the same time in mid-January this year, I noticed that a similar number of Lesser Scaup were feeding along a ¼-mile stretch of the Willamette River just over a mile east of me. (It’s awesome to have bike paths along both sides of the river here, with a pedestrian and bike bridge due east of me – one of five such bridges in Eugene, as opposed to just four for cars.)

West Bank Bike Path along the Willamette River in Eugene

I suspected these might be the birds that are flying over my house.

Lesser Scaup on the Willamette River

I used Google Earth to draw a line from where this loose congregation of feeding scaup were to my house, and then extended that line to the next body of water, and bingo – Fern Ridge Dam! For these ducks, this would be a commute of about nine miles.

The flight path commute of Lesser Scaup

On March 1, just before dark, I biked over to the area of the Willamette River where the ducks tend to feed most often, and just a few minutes after I got there, a group of some 20+ Lesser Scaup pattered across the river into flight, zipped downstream as they gained altitude, circled around, flew right over me, and headed in exactly the direction of my house. That’s when I knew I had basically confirmed the identity of the commuting ducks.

The westernmost bend of the Willamette River closest to Fern Ridge Reservoir

One thing I have not done is positioned myself at Fern Ridge Dam to see the ducks arriving. Given that it would probably take them at least seven minutes to get to the dam, it would be too dark to see by the time they got there, and then I’d have a 45-minute bike ride back in the winter dark along busy roads. No thank you. Still, I’d like to know whether they are roosting just above the dam on the reservoir or on Kirk Pond just below the dam.

I’ve also been having my early morning coffee on the back deck well before light, and I can hear the ducks flying back to the Willamette River each morning. But a just like every scientific inquiry that has been answered, more questions are raised.

Why these birds are making this commute only while it’s dark? My guess is that it’s safer. Peregrine Falcon is not a rare bird in this region, and they almost exclusively prey on birds in flight. Once a Peregrine has gained altitude above its target, there is little chance to escape its terrifyingly fast dive, and diving ducks, while built for horizontal speed and efficiency aren’t the most agile of birds in flight. As long as the ducks are on the water, they are safe from Peregrines, but in flight during the day, they are, well, sitting ducks.

Another bonus of my daily sunset vigils has been adding American Wigeon to my yard list. For several nights in a row, at least 10 minutes after the Lesser Scaup, when it’s much darker, I’ve been able to hear a flock of wigeon, and at least twice managed to spot the flock as they commuted in more or less the same direction. I presume these birds forage during the day at Delta Ponds and also move to roost on the reservoir. But this was a phenomenon that begun suddenly at the end of January and ended in early March. Why just then, and not earlier in the winter? Could these have been migrants and not locally wintering wigeon?

I’ve also started wondering how identifiable ducks are solely based on the whistle their wings make. There have been about five Common Goldeneye foraging on the Willamette River alongside the scaup, and I’m almost certain that I’ve heard them in flight when it’s been too dark to even see shapes; they have a very loud wing whistle, and I managed to get one pretty solid recording of them. I’ve determined that the scaup don’t have much of a wing whistle, but how distinctive is Common Goldeneye whistle? How does it differ from Hooded Merganser, or the obvious wing whistle in some dabblers, like Mallard and Wood Duck? Are the spectrograms of the wing whistles of each species diagnostic? My own sound library is lacking recordings of most of these, and while a Cornell compilation has an amazing recording of a Common Goldeneye whistle, it’s of a bird taking off, not one in mid-flight. The primary frequency and first harmonic of my recording match that one well, but it's not strong enough to show the higher harmonics nor the shape of each individual wing beat sound.

Incidentally, I’ve also noticed a pattern to the flight direction to many of the Double-crested Cormorants I see here. While a few seem to be clearly just commuting between the Willamette and Fern Ridge, a majority are off to the NE of my house by a few blocks, quite high, and headed in a NNW direction. I drew a line between the location on the Willamette where I frequently see numbers of them, just downstream from the Greenway Bridge, to the Junction City Fish Pond, which also is the only other place regionally where I see numbers of them. And bullseye – the line I draw between those two places on Google Earth falls exactly on the flight path where I see them. Curiously, this flight is almost exactly the same distance as what the ducks are doing.

Presumed Double-crested Cormorant commute