Tag Archives: migration

A third look at our 2020-21 “superflight” irruption – red crossbills

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As mentioned in my last couple blogs, finches that usually reside in Canada and the northern USA have come south this year because of a dearth of food in their usual habitats. One of the factors contributing to the shortage is the varying cycles in which cones, seeds and fruit ripen among different tree species.

Not every tree produces an equal amount of seeds or berries every year; for example, this year my red cedars didn’t have very many juniper berries and by the time the cedar waxwings arrived, the American robins (Turdus migratorius) had already cleaned out the crop. Periodically, many of the different tree species up North have low seed production at the same time, so that birds who eat different kinds of crops all need to go elsewhere for sustenance in the winter.

An interesting speculation from scientists in the Finch Research Network is that this synchronized low seed production evolved as a means of limiting food supplies for seed-eating (red) squirrels who could reproduce greatly and then wipe out all the seeds so that no new trees would grow. Jamie Cornelius, a researcher at Oregon State University, explained that “birds are mobile, and can find cone crops somewhere else,” while the sedentary squirrels then need to curtail their reproduction. In addition, some birds have evolved biological processes that make it easier for them to cope with food scarcity.

Red crossbills (Loxia curvirostra, called common crossbills in Europe) molt quite slowly, losing only a few feathers at one time, which makes it possible for them to fly elsewhere at any time in search of sustenance. They are normally not migratory but will travel for food, so in December 2020, local birders were quite excited when red crossbills were spotted at a state game lands in a neighboring county.

I was not enthusiastic about going to a hunting zone but had heard that the duck hunters were usually only busy early in the morning. So I donned my bright orange vest and ventured out on the two-mile walk to the spot where the crossbills had been seen. I waited around for a couple hours but they didn’t show, although I was looking for the reddish males and yellow females to make an appearance.

I didn’t give up. On my fourth visit to the game lands, I finally saw the crossbills (although I didn’t realize it immediately as they were so far away and my cataracts make seeing anything distinctly at a distance quite difficult. It was only after I enlarged one photo on the camera that I saw what they were! Remember, you can see a photo larger if you click on it and then back arrow to the blog).

I first thought perhaps some grosbeaks had flown in, so I focused as well as I could on the distant trees and took photos. I was thrilled to see that I had finally photographed those elusive birds – giving me a “lifer” for 2021. 😊

Sometimes it’s not easy to understand why a certain bird species has a particular common name. For example, many people would call a red-bellied woodpecker a red-headed woodpecker because the red on the head is much more noticeable than the hue on its belly. But the crossbills exemplify their common name quite accurately with their upper bills that curve down over their lower bills. A good view of their beak can be seen at the All About Birds website.

At first sight, one might think that this beak arrangement would make it difficult for them to eat, but this morphological adaptation means that they can extract seeds from conifer cones that are still closed, which other finches cannot do. Their bill structure makes it possible for them to hold onto a cone, pry it open with their beak and then take out the tightly-packed conifer seeds with their tongue.

This specialized anatomical feature does restrict the crossbills’ diet somewhat. They do eat some other seeds, berries and insects from time to time and they also ingest grit and sand from time to time as having these substances in their crop helps them to digest the conifer seeds.

What also makes these finches very unusual is that there are at least six – and perhaps as many as 11 – sub-species in North America who differ in the size and shape of their beaks and the type of calls they make. Their unique vocalizations has led to each sub-group being designated as a “call type” and each type feeds on a different conifer species. They move about in groups and call to each other while flying from tree to tree. Some scientists think they may be communicating about the feeding possibilities in each cone-laden tree they pass!

Another behavior that is distinctive for the red crossbills is that they breed at any time of the year, whenever sufficient food supplies are available. When a female and male form a breeding pair, they imitate one another’s flight calls so as to keep track of one another.

 

Unfortunately, unlike other irruption species such as evening grosbeaks and pine siskins, the red crossbills are rare visitors to bird feeders.

When I heard that crossbills had been seen at a game lands area much closer to my home, I made a couple more treks in hopes of spotting them. The first day I was incredibly lucky as I was the only person visiting the reserve and could walk at a leisurely pace in quiet fields except for the chittering of multiple bird species, including a hermit thrush.

Unfortunately, I didn’t manage to see any crossbills flying overhead. Another visit to this nearby game land was shortened considerably when I discovered it was quite noisy with two hunters accompanied by a pack of baying hounds who were yowling very loudly and frequently. I high-tailed it out of the reserve and resolved to be happy with my one and only crossbill sighting (so far). Hopefully, one day I’ll be able to see them more closely – something to which I can look forward with great anticipation!

A “superflight” irruption for North Carolina – the pine siskins

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As mentioned in my previous blog, North Carolina’s Piedmont region is experiencing a spectacular winter irruption of multiple finch species. So many birds have migrated south from the northern USA and Canada that scientists are calling this a “superflight” year. The first to arrive in my yard during this irruption were the pine siskins (Spinus pinus).

Scientists don’t yet know as much about siskin migration as they would like to know. From 1960 to 2011, almost 675,000 siskins were banded but only 2000 of them were ever spotted again.

However, it is known that the siskins enjoy eating many types of seeds. The finches’ usual diets up North center around the fruit and seeds of spruce, pine, hemlocks, maples, and beech trees, among others. Some species favor certain trees, while others enjoy eating a large variety of seeds.

In “mast years,” the forests provide large amounts of seeds that both feed animals (e.g., birds, squirrels) and provide the germination material for new vegetation. In other years, the forests produce very few crops because of fires, drought, and outbreaks of spruce budworms that eat the needles of spruce and balsam firs, which can kill the trees. In 2020, it was noteworthy that authorities in Quebec were unable to completely treat the forest trees for budworms because of the COVID epidemic.

 

Some trees also have slow biological cycles. For example, the Eastern white pine (Pinus strobus), known to the Iroquois as the “tree of peace,” has cone production that peaks every 3 to 5 years.

When mast years have taken place and there are large budworm infestations, the finches have plenty to eat and their numbers increase substantially. When the following seed- and cone-poor years occur, the large populations then need to travel further away to find sufficient food supplies and that is what has now brought them to our area.

The pine siskins arrived in my yard in late autumn. They came in a large crowd, with some 30 birds flocking to the feeders at a time. Most of these little brown and beige birds have a trace of yellow on their wings.

About 1% of the siskins – all males – have more yellow or yellow-green coloring on their backs, heads and under-tail coverts. These so-called “green morphs” also have less streaking on their chests. The siskins above may be in this group. Interestingly, whereas female birds of many species prefer brightly colored males as their mates, female siskins appear to choose males with less yellow to distinguish them.

 

What really distinguishes the siskins for me – in addition to their penchant for visiting in large groups – is their feistiness. They seem to be very troubled by the idea that there may not be enough seeds to satisfy their appetites if many other birds are around.

Below you see them challenging a house finch, a downy woodpecker and cardinals.

 

And this includes not only birds of other species but also their species mates with whom they arrive! They first will open their seed-filled mouths to “yell” at the incoming diners.

Next, they may open their wings in a challenging display.

 

Sometimes they seem to be taking food from another’s mouths! (But perhaps this is not aggressive but a sign of care between family members?)

Finally, they will fly at their food rivals in an effort to drive them off.

Unlike other members of the finch family, the siskins not only eat a very large variety of seeds from conifers, deciduous trees, grasses, weeds and flowers. They also forage for insects and have been seen to drink from sapsucker sapwells in trees.

A group of siskins can clean out a feeder with mixed seeds in my yard in very short order indeed. They have developed body mechanisms to help them survive cold nights: increasing their metabolic rates and gaining body fat for the winter.

 

This is accomplished by eating more seeds than they can process right away; they can store seeds weighing up to 10% of their body mass in their crop (part of the esophagus) for a short period so that they have access to more energy during the night!

 

Some local birders who were delighted to see them at the beginning of the season are now occasionally voicing “regrets” since large groups continue to visit their feeders. They could refrain from putting out seed and hope the flocks move away so they don’t spend so much on bird seed, but many birders would then miss seeing the other species and don’t want to forego that pleasure.

 

 

Fortunately, the siskins have been eating seeds from crepe myrtles and other trees in my yard so their visits to my feeders have been somewhat sporadic when the weather is mild. When it rains or gets very cold, they return in feisty groups!

“My” yard siskins have also refrained from pecking at the cement of my brick house. Other birders have seen them chipping away at chimney and brick cement – they do this get at minerals contained in the cement.

 

While the siskins migrate in very large groups (e.g., flocks numbering up to a few thousand individuals!), they are still considered to be a common bird that is showing a steep decline in numbers. They are vulnerable to predators as well as contagious diseases spread at feeders such as salmonella.

Although we are still in the throes of winter in North Carolina, spring is fast approaching and it’s uncertain how long these irruption birds will stay. I’ll miss these lively little visitors when travel back up North!

A gathering of gorgeous grosbeaks

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If you know birders, you’ve undoubtedly heard that this 2020-21 winter season marks an “irruption” year – a period when large numbers of certain bird species migrate to places where they’re usually not seen. This year is especially notable because it is one of the largest mass migrations that has taken place in about 25 years.

The scientists who study irruptions are calling this season a “superflight,” because all the species in the finch family that breed in the boreal forests of the northern USA and Canada have been moving south. Here in the Piedmont, we’ve been lucky to see several of these species.

The finches that have drawn the most attention from local birders are the evening grosbeaks (Coccothraustes vespertinus) with their eye-catching colors and plumage. They tend to move about in flocks and when they land at feeders, they appear more than willing to share with other birds, like a red-bellied woodpecker (above) or pine siskins (below).

When they land on a feeder, however, they may crowd out others due to their size.

While the evening grosbeaks don’t seem quarrelsome like some other birds, they may still have territorial defense encounters when they are vying for food. Perhaps that is what happened to this female with what appears to be a slight injury below her eye. It is unlikely that it would have come from escaping another type of assault as it has been reported that they have no known predators!

The females are subtly colored in shades of gray-beige with touches of green and yellow on their flanks, neck and near their throat. Their wings are marked with black and white patches.

 

Their coloring may look a bit different depending on the quality of the light and how overcast the day is.

The males are eye-catching due to their vibrant yellow and black plumage, featuring a notable dark yellow stripe over the eyes and a bright white patch on black wings.

Both females and males have the very thick, conical bills characteristic of their species.

Watching them at breeding time would be interesting as it does not involve song but instead features the males dancing for their prospective mates.

In the summer, the evening grosbeaks eat insects, including the spruce budworm, which is a tiny caterpillar. Their winter diet includes large seeds, berries and tree buds; maple samaras (papery winged seeds) and sunflower seeds are favorites (especially the gray-striped kind).

In 2018, a few individual evening grosbeaks were spotted in the Triangle but not many people had the chance to see them. I was fortunate to have three visit my feeders for an afternoon when it was snowy.

This year, none have visited me, but they have been very present in our area, especially at the feeders of bird enthusiasts Bert Fisher and Leto Copeley. This lovely couple welcomed birders to visit their yard by appointment (with limited numbers of visitors wearing masks in the large area).

 

Bert kindly updated everyone on the birds’ comings and goings. Their number increased over time to a high count of over 60 birds seen at one time. They often sit high in the trees of the wooded property and then suddenly descend to sit in groups on platform feeders and to pick up fallen seed on the ground.

Over time, the evening grosbeaks have expanded their “territory” over the Northeastern USA, partly in response to increased planting of boxelders (Acer negundo, a type of maple) as shade trees. The seeds of the box elder are available throughout the winter and are a preferred food for these large finches.

Like numerous other bird species, evening grosbeak populations have declined steeply over time. Between 1966 and 2015, their numbers on the East Coast declined by 97%. Continued logging of forests in northern North America, avian diseases, aerial spraying of insects and climate change may all contribute to further reductions of this group of birds.

Researchers are now collaborating in an Evening Grosbeak Project that aims to compare flight calls, genetics and breeding behaviors of five distinctive sub-groups in this species. They are distinguished by the types of calls that they make and birders are asked to help out by submitting recordings to the eBird website.

It appears that Type 3 (Coccothraustes vespertinus vespertinus, the most irruptive of all five sub-groups) is the call type which has traveled to our area. It has a call that is similar to that of a house sparrow.

Some northeastern grosbeaks are now being tracked by the Project. An avian ecologist with the Pennsylvania Natural Heritage Program recently was able to band 47 birds so that sightings of them elsewhere can be reported. He also put a new model of solar radio tracking tags on 29 of the birds, which can help monitor their movements throughout their lifetime.

Evening grosbeaks can live well into their teens; the oldest banded individual was found when he was 16 years and 3 months. Perhaps some of those visiting us this year have been here before during food-poor periods up North. It will be interesting to see when they next decide to visit our area in the future and hopefully a few will visit me.

 

I’ve added some of the trees that tend to attract them, such as winterberries, maples and crabapples, to complement the junipers, pines and elms in my yard, so the welcome mat will be out!

Serendipity in a stressful year

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2020 has turned out to be quite a stress-filled series of months on multiple fronts, so unexpected pleasures and delights are very welcome. For birders in North Carolina (NC), that scenario has luckily been playing itself out this fall and winter. Several unexpected and unusual birds have been spotted in our state, including a Kirtland’s warbler, vermilion flycatcher, MacGillivray’s warbler, and sandhill cranes.

Many bird lovers have traveled to catch sight of these surprising visitors. While I’ve mostly avoided groups the past nine months as part of my COVID-avoiding measures, last week I did join the human migration to an NC home about 20 miles away to see a bird that is normally only found in the northwestern United States – a varied thrush (Ixoreus naevius).

The opportunity to see this lovely bird was offered to the local community by homeowners Tony Hewitt and Marla Wolf. They generously allowed people to come to their suburban yard (by appointment) to watch over the backyard fence to catch sight of the thrush.

When I visited on a “slow” day, it was easy to socially distance oneself from other birders and photographers. Only a couple other people were there for a while (and I was alone some of the time) waiting for the thrush to make an appearance. Everyone wore masks, some having double masked as well.

The varied thrushes normally migrate back and forth in the area stretching from Alaska, through Canada, down to northern California, as shown by this map from the Cornell Lab of Ornithology. The website remarks that a few of these birds occasionally wander outside their normal range to the Midwest and Northeast. Seeing one in the southeastern USA is highly unusual.

Map credit: https://www.allaboutbirds.org/guide/Varied_Thrush/maps-range#

This robin-sized bird is a real stunner – his orange, grey, yellow and white feathers grow in a wonderful pattern. The colors seem to vary a bit, depending on the quality of the light falling on them and the background against which you see him. But he is handsome from any angle – front, side or back!

Something I found particularly interesting was a pattern of wavy lines in his tail feathers when the light hit them in a certain way. This was not something that I saw mentioned in descriptions of its physical characteristics. The observation made me want to photograph the thrush again to see if this would show up again.

 

It is interesting to note that one varied thrush crossed the Atlantic and turned up in Great Britain in 1982. It was a unique bird since it represented a rare variant of the species in which the orange feather coloration has become all white. Only five such representatives of this mutation have been recorded since 1921.

In its home range, the varied thrush prefers to stay in dense, coniferous forests near water. The NC visitor is taking advantage of a backyard nook that Marla designed with multiple shrubs and some open space.

The home is not far from a lake, but the thrush is taking advantage of a bird bath for drinks, which Marla kindly had moved so that it was better visible for visiting birders looking over the fence.

Varied thrushes usually feed on insects, foraging on the ground and often under dense cover.

The thrush’s insectivorous diet can be wide-ranging and include ants, beetles, caterpillars, crickets, earthworms, millipedes, snails and spiders.

  

They also eat berries, either in trees or on the ground, during the autumn and winter months. 

Our NC celebrity bird is obviously enjoying seeds furnished daily by Tony and Marla.

A notice placed by Tony near fence announced that the thrush seemed to come out in the open every 30 minutes or so. It turned out that this was indeed the case the first hour that I was there; then the bird came after a couple 15-minute intervals.

He certainly seemed to be a creature of habit because I noticed that after eating, he would go back into the dense undergrowth for several minutes and then re-emerge to take a couple drinks at the bird bath. Eating obviously was making him thirsty and noticing this habit meant it was possible to get “camera-ready” for another appearance.

When it is breeding time, male varied thrushes begin to establish territories and confront other males with threat displays. These begin with the bird cocking his tail and turning it towards his rival, while he lowers his wings. If the rival bird does not go away, the thrush will lower his head, raise and fan his tail and then spread his wings out to the side.

Obviously, our NC bird had no rivals around but there were many other birds foraging in the ground underneath the feeders. They included Northern cardinals, white-throated sparrows, pine siskins and downy woodpeckers among others. And it seemed that “our” thrush was sometimes warning them off.

Or perhaps he was just flashing his wings to scare up insects hiding in the fallen leaves.

There are still large numbers of varied thrushes, with an estimate of some 20 million in the current global breeding population. However, the North American Breeding Bird Survey recorded a cumulative decline of the species of 73% between 1966 and 2015. Logging, wildfires and forest fragmentation are ongoing threats to their breeding habitat.

This is only the fifth time that a varied thrush has been seen in North Carolina. The first sighting was in 2005; three other birds were seen in 2010. No one has any idea what got this year’s bird so far off-course during its migration and no one knows how long it will stay around.

Tony and Marla have kept a visitors’ book (with hand sanitizer available for signers) and many people have been recording their visit. When I visited, more than 110 people had already come by, including some birders from Virginia and Tennessee. More people have since stopped by the Hewitt-Wolf residence to admire this vagrant bird. We are grateful to them for giving us this opportunity!

It’s apparent that the serendipitous sojourn of this gorgeous bird has been a welcome gift to many people – both those who saw it in person and those who’ve admired photos distributed through facebook groups. We hope the bird will survive the winter here and be able to return to its home grounds out West so that its journey has a happy ending!

 

‘Rassing – a surprise visitor – what a delight!

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(Warning – this is a bit of a long blog!) Several years ago, what was likely a rufous hummingbird took up residence in my yard during the winter months. That was really unexpected — while it’s not uncommon for migrating or some resident hummingbirds (especially ruby-throats, Archilochus colubris, above) to spend wintertime in North Carolina, particularly along the coast, it’s not so common in the central part of the state. That experience taught me that it’s a good idea to keep up a nectar feeder in the winter as you never know when a stray migrant might show up. In 2015 and 2016, I traveled with fellow birders to visit people who had a buff-breasted (Amazilia yucatanensis) and calliope hummingbird (Selasphorus calliope) wintering at their homes. In actuality, however, I didn’t really expect a rare passerby in my yard.

 

It was consequently with great surprise that I saw a hummer hovering at the nectar feeder last week. “Oh, wow!” I thought; “a ruby-throated hummer is passing through as a very late migrant.” I grabbed my camera to take a few shots and immediately felt perplexed.

 

The bird looked like he had a purple rather than ruby or red gorget (throat feathers). The white patch behind his eye also showed prominently because of his very dark head.

To me, it also looked as if this hummer had blue patches on his tail feathers. (Most say his flanks are green and a hummingbird expert said he has iridescent black tail feathers; the way the light reflects off them made me see blue, however.)

I got a few photos and cautiously asked birding experts on a facebook group if he could possibly be a black-chinned hummingbird (Archilochus alexandri), also sometimes known as the Alexander hummingbird. It seemed unlikely as their normal range is the Western part of the Northern hemisphere, reaching north into Canada (Alberta and British Columbia), east to Oklahoma, and as far south as Mexico, where most spend the winter.

A couple people thought I might be correct, but most thought it was a ruby-throated hummingbird. My spring-summer ruby-throated residents had left at least a month ago but I thought perhaps a late migrant might have arrived. The next day, I saw the bird again and became convinced that it was a black-chinned hummer; his purple gorget was very obvious to me. I posted new photos and now the experts agreed that I was correct. That was very cool – I got a lifer without even leaving my own yard!

 

A couple days later, North Carolina’s hummingbird researcher, Susan Campbell, came to my home to band the unusual visitor. I invited a friend who had been to bird bandings in my yard before to come for the happy event.

Susan arrived early and first set up a cage trap for ‘Rassing (short for the Dutch word verrassing, which means surprise; I wanted him to have a name during his stay 😊). She left the door open with a long string attached and hung the nectar feeder on the outside. It wasn’t long at all before the bird arrived for a drink. When he left, Susan moved the nectar feeder inside the cage.

‘Rassing returned for another drink and flew right into the cage, which Susan shut promptly. She had already laid out her banding materials so she could remove him from the trap promptly.

He went into a small bag (the kind often used to hold birds for banding) which Lucretia held while Susan began filling out the paperwork.

Then the actual banding procedure began. Susan first checked his legs to ensure that he hadn’t been banded already – the hummers rarely show their legs so that was necessary.

Then she got ready to put a thin red metal band on his tiny leg with a silver band showing his numeric code for identification in case he is caught again some time (Band number 7100 (M)-41902).

She checked the length of his bill – 19.19 mm. She also advised that bird feeders with long slits are not preferred even if the birds like them. It turns out that the thin slots can rub against the bill and wear it down, damaging the bill and making it vulnerable to infection. (I afterwards enlarged the slots into ovals and circles and went back to a couple other feeders I had with larger holes.)

She blew on his stomach feathers to check his fat; he was not a hefty bird but certainly a healthy adult male. His weight turned out to be 3.09 g. She also recorded his body length.

She stopped for a moment so I could take a few photos trying to get a good shot of the purple gorget. It looked like ‘Rassing was trembling but this was the vibrations from his rapid breathing. (When resting at 91⁰ F, they take about 245 breaths per minute; at 55⁰ F, this rises to 420 breaths per minute!!) Susan thought he was acting fairly calm.

She measured his short tail (23.5 mm), as well as his wings (40.42 mm). The female black-chinned hummer would have more rounded wing feather tips than this male.

 

Susan took a few photos of ‘Rassing and he got a few long drinks from a feeder held by Lucretia. Then Susan gave me the honor of releasing him – and to my delight, he chose to sit in my hand for what seemed to be at least 90 seconds. I could feel him breathing and it was a real thrill to see him so close. With a little flutter of his wings he took off – and then stayed away from the feeder for quite some time.

 

I added a feeder in the backyard and ‘Rassing began preferentially feeding there – perhaps the front yard had acquired some unpleasant memories. However, at the end of the day, I would remove the backyard feeder so that visitors who wanted to see him had a better chance of seeing him dine at the front-yard feeders.

 

 

A fair number of birders were interested in being able to add him to their life, state and county bird lists, so I offered to schedule visits through a birding listserv for a few people at a time. ‘Rassing appeared more reticent to stay at the feeder when there were more than 2 or 3 people watching, which is understandable. Who wants an audience for each meal and snack you eat??

When it rained, the feathers atop his head clumped together, giving him a new “hair-do.”

 

 

It appears that this species of hummingbird has not been studied much. I found his behavior interesting and spent a good amount of time observing him (chores had to wait). When I watched him leave the feeder and go to a nearby tree, he would sometimes watch me (turnabout fair play, of course).

 

 

He seemed very comfortable with lots of other bird species at nearby feeders. Perhaps it gave him a safer feeling.

‘Rassing tended not to sit on feeders, as ruby-throated hummers often do. Instead, he mainly hovered and vigorously pumped his short tail quite a lot. I learned that this tiny bundle of energy was breathing at a flight rate of about 1260 beats per minute!

 

Occasionally, you could see the band on his leg but mostly he kept his legs tucked into his body.

In the evenings, he came around nearly the same time each day to have a longer drink and then he sometimes perched while feeding.

 

A Cornell University website says that black-chinned hummers rarely stay at a feeder longer than a day during migration, even when food is scarce. In my yard, he had access to lots of bugs (I have a small pond) and three types of sage/salvia were still blooming. Indeed, he sometimes came to the feeder with pollen covering the top of his bill.

Yesterday morning, ‘Rassing apparently had decided it was time to move on. After the warmest Halloween on record in our area, the temperature plunged during the night to the 30s. The next morning was the same and he may have decided it was time to go to warmer climes.

 

I did feel lucky that he graced my yard with his presence for a week; it gave me something to celebrate during a personally challenging time. The oldest known black-chinned hummer was more than 11 years old; if ‘Rassing likes going east during migration, perhaps he’ll stop by again next year – wouldn’t that be a tremendous surprise! 😊