This winter there were a couple of absentees from my bird feeders. One species that I missed was the siskin.
Most winters they arrive in flocks, mixed with redpolls and goldfinches, and although they’re one of the smallest of our finches, they compete bravely for the choice positions on the seed feeder.
They are adapted to feeding on tree seeds in the woodland canopy, mostly confers in spring and summer and alder and birch in winter. This means they are extremely agile and just as happy feeding upside down.
The males are also very colourful, particularly in their spring breeding plumage, with olive, yellow and black upper-parts, a jet black skull cap and a deeply forked tail. The females are a bit dowdier in colour than the males but share their pugnacious personality.
So I was delighted when eventually, in early April, one pair turned up and are now regular visitors.
Although siskins are Irish breeding birds their numbers are augmented in winter by migrants from northern Europe, particularly Scandinavia and western Russia.
The size of these migrations and their route varies considerably from year to year, for reasons ornithologists argue about, and it’s possible that fewer birds than usual arrived in Ireland last winter.
But I’m not convinced by this explanation because friends of mine who feed wild birds seem to have had plenty of siskins. Another possibility is that there was plenty of birch and alder seed in the area and the winter flocks just didn’t feel the need to visit my feeders.
It was only when the flocks broke up at the end of March and the breeding pairs formed that one pair decided to stake a claim to a territory in my garden.
Winter migrant siskins have presumably been arriving in Ireland for thousands of years. But 100 years ago they were rare and very localised as an Irish breeding species. Today their numbers have increased so dramatically that they figure among the top 20 commonest birds in BirdWatch Ireland’s garden bird survey.
There are two reasons why they were once so rare. The main one was a lack of trees. A lot of coniferous forestry was planted in Ireland in the 20th century, and siskins, along with redpolls, are one of those species that thrive in coniferous forestry plantations.
It’s not just that the seeds in the young cones are an important source of food in spring and summer, they also have a strong preference for nest sites that are high above the ground in tall conifers.
The other factor is that siskins are colourful and have a pleasant song. This meant that large numbers of them were captured using traps, nets and bird lime, for the cage bird trade. This trade has been almost completely eliminated in recent years.
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