Greenfinch (Carduelis chloris)

General characteristics

The Greenfinch, known by the Latinate name Carduelis chloris, is a relatively common finch, resident all year round in the vast majority of the UK except for the extreme north of Scotland. It is a bright, colourful and stocky garden bird with a highly distinctive forked tail. Males, as is common with many bird species, feature a brighter plumage, which tends to be of a striking olive-green hue; you’ll notice on the outer areas of the wing and tail feathers a clear yellow colour with some dark streaks along the tail. Both females and juveniles are of a somewhat duller colour than male Greenfinches. All Greenfinches have a surprisingly powerful and chunky bill, perfect for consuming seeds.

The total UK population is currently 1.7 million breeding pairs (RSPB source); they regularly visit gardens to take food, and their favourite places to stay include woods and hedges. Listen out for a “dzweeeee” or a “chichichichichit” (in flight), and you’ll most likely be near a Greenfinch.


Greenfinch

Greenfinch diet

Greenfinches are avid seed eaters, their strong and substantial beaks being well-adapted for the purpose; and, furthermore, their enthusiastic feeding behaviour means they have the potential to feed at length in your garden – if you’re lucky enough, you could observe mammoth feasting sessions of up to half an hour.

Their diet in the garden primarily consists of black sunflower seeds or hearts, peanuts, a variety of seed mixes, as well as insects. They are more than content to sit on hanging feeders and will happily feed in the company of other garden birds. Between early autumn and spring, it is not uncommon to find Greenfinches feeding gregariously in communal flocks.

Nesting behaviour

Greenfinches have the habit of sticking together in “loose colonies” of approximately four to six nests, and there’s a strong preference for nesting within evergreen shrubs. The nest itself is built from twigs, moss and grass, and the most common lining is hair.

You may hear male Greenfinches beginning to sing in late January, ready for partnering from around late February. Breeding starts in April and the usual clutch consists of between 3 – 8 eggs. Incubation lasts between 12 – 14 days. The eggs are a smooth, glossy white and have blackish markings.

Trichomonosis

There’s hardly a mention of the Greenfinch without reference to Trichomonosis (Trichomonas gallinae). But what is it?

Trichomonosis is a virulent parasitic infection that has been notable in the recent, sharp declines of, primarily, Greenfinches and Chaffinches, although the disease has affected other garden bird species such as pigeons, House sparrows, Dunnocks, Great tits and Siskins.

Affecting the back of the throat and the gullet, making it difficult for Greenfinches to feed, Trichomonosis can cause excessive salivation and vomiting, which means the disease can spread relatively easily while birds are feeding on feeders. The disease spreads dramatically throughout the breeding season when parent Greenfinches feed their young.

It is therefore essential to keep feeders and bird baths clean if your garden attracts Greenfinches to prevent, as much as possible, the disease from spreading. Once cleaned, allow your feeders to dry out thoroughly before using again, as the process of drying can kill the infection. Trichomonosis cannot survive for long outside the host.

Due to the different migratory routes taken by Greenfinches and Chaffinches: Greenfinches migrate directly to and from Northern Europe over both seasons, whereas in Spring the Chaffinch diverts via Germany, Denmark and Belgium, thus increasing the likelihood that Trichomonosis was spread in mainland Europe by the Chaffinch.

Can humans contract Trichomonosis?

Bird diseases, such as the likes of Trichomonosis, rarely ever affect humans. In fact, there has never been a report of a human infected with Trichomonosis. Despite this, it is better to be safe than sorry, so make sure you wear appropriate protective gloves when tending to any potentially infected feeder or bird bath; once cleaned, wash your hands and forearms thoroughly before eating or drinking, and keep any cleaning tools (brushes etc.) outside to dry.


“Trichomonosis is widely acknowledged to be a causal factor in the rapid decline of the British Greenfinch population that was first noted in 2006.”


Further resources

Should you observe any Greenfinches, or other species, showing signs of Trichomonosis infection, you can refer to the following resources for information and help.

Greenfinch vs Siskin

A pair of commonly confused garden birds: see the images below for a side-by-side comparison of the Greenfinch and Siskin

Male Greefinch (Carduelis chloris)

Male Greefinch (Carduelis chloris)

Siskin (Carduelis spinus)

Siskin (Carduelis spinus)