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

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

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

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!

Some beauty to offset a distressing week

This past week in the USA has been rather distressing as far as health and politics are concerned. The COVID epidemic is wreaking havoc and then humans wrought havoc during a procedure intended to be part of a peaceful transition of governmental power. So we can all use a bit of distraction to remind us there is also still beauty in the world and I’ll end my last trio of posts with one more view of hummingbirds – this time featuring the one species that visits my home every year, the ruby-throated hummingbird (Archilochus colubris).

Fortunately, my yard now has several types of plants that offer the hummers natural nectars to complement their primarily insectivorous diet.

The rose of Sharon (Hibiscus syriacus) flowers are a popular feeding site.

They are also fond of the blue-black sage (Salvia guaranitica). My original plants were a gift from birding friend, Gail; now they are growing in four areas of the yard. Sometimes a hummer doesn’t want to hover but uses a nearby prop to offer some less strenuous feeding. And then the bird can close its eyes to thoroughly enjoy the sweet sap.

Hot lips sage shrubs (Salvia microphylla ‘Hot Lips‘), which I got at a garden center, have proved to be popular feeding sites. This is quite a hardy plant.

The hummers also like going to the lantanas (Lantana) and the yellow passionflower (Passiflora lutea), which kindly came to my yard on its own.

 

Another popular plant is the butterfly bush (Buddleia davidii).  Many recommend against planting this bloomer because it can be invasive. However, some garden centers have developed varieties that scarcely seed and that must be what I luckily got as it has never appeared anywhere else in the yard in more than a decade.

It also attracts butterflies, bees, syrphid flies and hummingbird moths, so I’m quite happy with my butterfly bush.

The ruby-throats also do like their nectar, however. After visiting various flowers, they often take a seat near or on the nectar feeder so they can sip at their leisure.

 

They will also do their best to keep other hummers away from the nectar feeder — even when I have as many as three or four feeders available.

They keep an eye out for intruders.

When a rival appears, it can lead to confrontations. Mostly these involve aggressive displays and chasing one another; only very rarely have I seen them actually physically engage.

This past summer, a few laid-back moments occurred when they tolerated one another.

It’s not only the males who are aggressive; female hummers can also be quite protective of feeding grounds. This past year, it seemed that I had mostly males visiting. While a female hummer can have one or two red spots under her chin, usually that is the beginning of a young male developing his ruby-throat.

It can be fun to watch as more spots appear with passing days.

 

Eventually, the males get their fully developed gorget, which can be quite stunning.

The red hue is very dependent on how the light hits their feathers. In some cases, the red feathers almost look black.

  

The hummers take care to groom their feathers.

They take advantage of the rain to have a shower.

There are times when they look a bit scruffy, however. That is when they molt. This process of replacing old feathers with new ones usually takes place on their wintering grounds. This past summer, the hummers seemed to have lingered longer than usual and began molting before their trips further south.

White feathers appear more and more as molting proceeds. And feathers come loose before falling away.

They can look a bit scruffy during this time.

Eventually, they get back to their pretty selves. It always stays fun to watch them flying — at least for me. That is when you can see their tiny feet better.

And you get an idea of how rapidly their small wings move as they hover and soar.

They can beat their wings up to 70 times per second!

It doesn’t seem to me that I’ll ever tire of watching these tiny fliers; they always are entertaining. I hope seeing some photos of them in action have provided you with a brief respite from the worries of the world, too.

Flying shades of bronze, brown and copper

While the hummingbirds “clothed” in vibrant green and blue hues in Costa Rica are really wonderful (previous blog), I found out that I’m really attracted to some hummers with more subdued hues as well. The photo above is probably my favorite hummingbird photo of my 2019 trip — that long-billed hermit (Phaethornis longirostris) was simply gorgeous!

Before showing you some other shots of this stunner, let’s look at some other hummers with hues of bronze and copper. The rufous-tailed hummingbird (Amazilia tzacatl) is a smaller bird but a pleasure to see as it flits from bloom to bloom.

These medium-sized hummers defend their nectaring territories vigorously, which may lead to some ruffled feathers. Scratching an itch can also lead to the same condition.

The bronzy hermit (Glaucis aeneus) has a long, curved bill which is useful for the types of flowers where it seeks nectar. It is known to be a fast flyer and is said to only stay a few seconds at each feeding site, so I feel lucky to have gotten a photo of it!

When I saw the black-bellied hummingbird (Eupherusa nigriventris), I immediately fell in love.To me, it looked like this male had had a crew cut and then covered himself with black velvet.

The females of the species do not have black bellies but are also pretty.

Another species that really caught my fancy was the brown violetear (Colibri delphinae). They are very muted in color, which is what makes the color patches really stand out.

The blue-green throat feathers shine. And the violet stripe behind the eye is certainly eye-catching!

It must be the real contrast between the overall subdued coloration and the vivid color patches that attracts me. As other birders moved on, I stayed behind to watch them for a while.

I would enjoy seeing this hummer in person again!

I will leave you with a couple more photos of the wonderful long-billed hermit. The lengthy curved beak and long tail feathers make for a very attractive presence.

And this elegant hummingbird also has a distinctive mating behavior. Up to 25 males will gather in a lek (a communal area where courtship displays are done) and begin wiggling their tail feathers. They then compete to sing a song that will induce a female to choose them as the sire for their young!

Seeing a courtship contest among the long-billed hermits must really be a wonderful experience. But I’m just glad I got to see this species at all and hope perhaps to do so in person one more time!

Next blog: one more view of hummers — this time in North Carolina.