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!

Birds using salt blocks

In the past, I have put out salt blocks for the deer to use in winter, but then I learned that other animals will use them as well. I have seen squirrels and rabbits licking at the blocks and chipmunks in their vicinity, but I was most surprised when I first saw purple finches (Haemorhous purpureus) pecking away at them.

squirrel at salt block IMG_5209 ©Maria de Bruynsigned resrabbit at salt block IMG_6254©Maria de Bruynsigned

At first, I thought this was abnormal or unusual but a specialist with the Audubon Society/North Carolina wildlife department told me that finches and other bird species will do this regularly to obtain salt when it is lacking from their diet. They also use the salt to help clean out their gizzards (an organ behind the stomach that helps break down seeds and food so that the bird can digest it more easily).

male and female purple finch at salt block IMG_7614©Maria de Bruynsignedresmale and female purple finch at salt block IMG_2733© Maria de Bruynsigned res

Apparently, mourning doves, sparrows, grosbeaks, pine siskins, goldfinches, house finches (Haemorhous mexicanus) and purple finches (like those in the photos) will all peck at salt blocks. So far, I have only seen the purple and house finches doing it.

Sometimes, they have had mini-gatherings there, making the salt block a place for socializing!

purple finches at salt block IMG_7605©Maria de Bruynsignedrespurple finches gathering at salt block IMG_4244©Maria de Bruynsignedres

Balancing on the block can also involve some acrobatics.

house finch IMG_9840©Maria de Bruynreshouse finch IMG_9841©Maria de Bruynres

It’s nice to have something to offer them besides suet, bird seed and bird baths.

Next week’s blog: acrobatic squirrels