Return of the kernel-crusher
As the species becomes more apparent in autumn, David Callahan investigates the life and times of one of our most ostentatious woodland birds – Hawfinch.
Astarling-sized bird suddenly appears in a deciduous woodland, flying overhead with deep bounds and fast wingbeats, flashing big white bars in the wings – is it a Great Spotted Woodpecker? There’s a lack of black in the plumage and it has a massive head that makes it look as if it’s about to plummet beak-first out of the sky: this is a Hawfinch, Coccothraustes coccothraustes, the largest of Britain’s breeding finch species, weighing twice as much as a Chaffinch at around 50 g. It’s a noteworthy sight.
A scarce and declining resident, Hawfinch’s British numbers are sometimes boosted in autumn by irruptive members of the northern European population. Even so, sightings in Britain are usually few and far between. The species’ current relict home range is restricted to pockets of forest, the largest of which are in the Forest of Dean, Gloucestershire, Coed y Brenin Forest Park, North Wales, Grizedale in the Lake District, the New Forest, Hampshire, and the woods of north Kent.
Far ranging
Hawfinch is found across the Palearctic region, with a range extending from Britain down to Morocco in the west and across Europe and Asia to Japan. It shares its genus with Evening
Grosbeak of North America and Central America’s Hooded Grosbeak (and is closely related to other American grosbeak genera).
The genus is known from fossils to have evolved by late Pliocene times (2.5–3 million years ago) in the Balkans, at least. Fossils of definite Hawfinches are known from about one million years ago from Poland, with one found in 1910 containing perfectly preserved cherry kernels in its stomach.
There are six accepted Hawfinch subspecies: the nominate form, found across most of the range from Europe to northern Mongolia, plus the more isolated forms buvryi in north-west Africa, nigricans from the Near East north to Ukraine, humei in the more arid environments of Central Asia, shulpini in China and Korea and japonicus in Japan. Plumage variation is nuanced among these forms, but the species in general has a huge slate-grey beak, almost half the size of its skull, a brownish-orange head, grey neck, reddish-brown mantle and scapulars, black wings with a broad white bar, and pinkish underparts with a white vent and undertail coverts. The rump and tail are pinkish brown, the latter tipped with white and having sides edged with black.
Males have glossy blue-black flight feathers, but the female can be distinguished by a cigarette-ash grey panel in the duller black secondaries and an overall slightly duller tone to the plumage (though immature males can be very similar). Juveniles resemble a sepia-toned version of the adults, with various shades of orange-brown on the upperparts, blackish flight feathers and off-white underparts daubed with darker brown brush marks.
Bill of might
The most immediately striking aspect of Hawfinch physiology is that bonecrusher of a bill. This huge bolt-cutter is controlled by 1,545 mg of muscle mass, five times that of a Common Rosefinch and almost 10 times that of a Eurasian Siskin. The beak can exert pressure of 57 pounds per square inch – approaching 1,000 times the bird’s own weight – making its generic name, ancient Greek for ‘kernel breaker’, well earned, as the blood-smeared fingers of a number of ringers can also attest! In human terms, imagine having a 60-tonne bite …
The bill is structured like a larger version of a normal finch bill, where the lower pointed mandible can pierce seeds manipulated by the larger upper
mandible, but also has four horny pads on the top and bottom palates which grip and distribute the pressure to crack a nut. This top-heaviness means the species presents larger and heavier than it really is, and its body is only slightly longer than a Greenfinch when laid on its back.
The most desirable habitat for a Hawfinch is mature, ungrazed, lowland and sub-montane oak and hornbeam forest, though it will use Wych Elms, beech, Alder, Yew, hollies and limes and more general mixed deciduous woodland, as long as at least the first two types of tree are present. Usage of secondary, young-growth woodland and open ground for foraging seems to be a recent development, enabling survival in ever-shrinking forest habitats.
Hawfinch rarely eats hawthorn berries, but does visit cherry orchards (and also raids pea and bean crops in gardens, and olive groves on the Continent), making it somewhat unpopular with fruit farmers, as its huge beak enables it to crack open the kernels of this remunerative produce. One or two cherry pits are mortally poisonous to humans – fans of the Netflix series Ozark will have seen the character Darlene Snell kill her husband by adding ground cherry pits to his coffee – but Hawfinches will happily eat them. Cedar Waxwing is able to digest berries with a cyanide content 5.5 times that which would be fatal for a rat, and it is likely that Hawfinch is just as resistant to this lethal toxin.
Cherry picked
However, despite the fruit being a small part of the finch’s diet, its history in Britain is indelibly linked to cherries. Two of its traditional names are ‘Cherry Finch’ and ‘Gean Finch’ – a ‘Gean’ being a Wild Cherry – and its first mention of being present in Britain, according to Guy Mountfort, was by Thomas Browne in the 17th century, who stated it was: “Chiefly seen in summer time around cherrietime.” Cherries begin to ripen in July and August, and in the 19th century farmers in Kent would shoot parties of Hawfinches and leave the remains suspended from gibbets to deter further raids by the species.
It seems the finch may have relied on the much larger cherry crop to sustain its greater numbers a century or more ago. Even so, the bird may have also been doing the fruit growers a service at the same time, as the chicks are fed plenty of caterpillars, grasshoppers and snails in the nest in summer. The bird is now so scarce here that these depredations are marginal at best.
It supplements its diet with buds, shoots and fruit, including mistletoe and honeysuckle. It generally forages in the crowns of trees during late summer, on the ground in winter – where it can be surprisingly unobtrusive – and at all levels at other times, this behaviour being mostly dictated by food availability. Hawfinch can range up to 16 km while foraging, according to GPS tracking data, using hedgerows and gardens near its forest territories. The species roosts communally in winter – with recorded Continental gatherings of between 300 and 1,200 and historical British flocks of up to 260 – and sometimes nests communally among larger populations.
Populations in arid zones favour thorn scrub and open steppe woodland, although it avoids coniferous monocultures. Like Common Nightingale or Golden Oriole, Hawfinch’s habitat specialisation in Britain may be an edge-of-range facet; in fact, it may have been a recent colonist in the early 19th century, when the first nesting was confirmed – prior to that, it was seen as a scarce winter visitor (though don’t underestimate the elusiveness of this pimpernel of a bird). Even so, the global population is estimated at up to 20 million, half of which is found in Europe; it is among the most common bird species in Poland’s Białowieza Forest, with 1.5 pairs per hectare.
It’s an early breeder, starting in March and finishing in August, forming a relationship with a long-term partner that can last two or more seasons.
Two broods are possible within this limited time and females are known to move several miles from the first nest to start a second brood. Somewhat contradictorily, Hawfinch prefers to nest near open glades and tracks, but in the densest parts of a forest.
The male’s display involves stiffly holding its wings out, ruffling its feathers, puffing out its breast and nodding its head downwards, which almost gives the impression of trying to keep its balance on the branch. If this attracts a female, they will face each other, ‘kiss’ by touching bills, followed by the female adopting a ‘submissive’ posture while being ritually fed. The male sometimes performs a slow, fluttering airborne display resembling a giant moth.
Both sexes collaborate on a substantial shallow nest of smaller twigs, bark, dry grass and moss, on a foundation of large twigs fixed close to the trunk of a fruit or seed tree with denser foliage, often hidden in ivy or honeysuckle high up in the canopy. This is usually placed on the southern side of the tree for warmth and shelter from the elements – there are more south-facing nests during colder springs.
Nests are placed up to 30 m above the ground, although the average is about 18 m, making it one of the highestnesting European passerines. This is high enough that researchers from the RSPB’s Centre for Conservation Science are trained to climb trees when installing cameras to observe nests. Such a preference for the canopy means that birds are as likely to breed at a forest edge or within its depths, perhaps a recent adaptation to suboptimal habitat and ancient forests destruction.
About four beige-toned eggs are laid, lightly action-painted with brown blobs and incubated for about a fortnight. Both parents look after the chicks, which are altricial (undeveloped) at first but fledge within 30 days. Though the adults are tough, the eggs and chicks remain at the mercy of martens and squirrels, corvids, European Sparrowhawk, Northern Goshawk and even Red-backed Shrike before they leave the nest.
A Hawfinch’s call is similar to European Robin’s: a cold, metallic tzik, classically uttered while flying above the canopy. Its less frequently heard song adds to this call with seemingly random tones resembling the squeaks of an unoiled hinge, though birds can be very quiet when displaying.
Where to see
British birders can see both migrating and resident birds, particularly away from the species’ few core centres of distribution. While it is largely sedentary in Europe, more northerly birds move south in local dispersals, altitudinal movements or minor irruptions and can turn up in numbers, initially in Shetland or Orkney – even at garden feeding stations.
Many northern Hawfinches winter in Spain and Portugal, the Balearic Islands, Corsica and Sardinia, and even North Africa, and it regularly passes through Gibraltar in autumn; vagrants have reached Saudi Arabia. Asian birds migrate more extensively to the north, east or west, with one ringed bird being recovered in Siberia 3,900 km west of its Korean wintering site.
Wintering flocks seem to be nomadic like crossbills, largely controlled by the beech mast or Hornbeam key crop. Poor yields in Sweden will lead to greater
numbers in Denmark and Germany, as well as presumably passing through Britain, and such transient sightings are relatively frequent during an irruption year. The last two notable ‘Hawfinch years’ were over the winters of 2005-06 and 2017-18.
On the Continent, Hawfinch is a fairly common woodland finch, but the species’ population has nosedived in Britain, from up to 6,500 pairs in 1980 to no more than 900 pairs in the first decade of this century, along with a range contraction of more than 75%. This acceleration in decline can be vividly illustrated by comparing the breeding ranges and figures in the three BTO Bird Atlases; in 2017 it was estimated that there was a maximum of 121 pairs left. Similar declines have occurred in parts of northern and central Europe – though global numbers have shown a slight increase between 1980 and 2013.
Research into the reasons for this is ongoing, but suspected contributory factors include an interlinked ‘perfect storm’ of reduction in ancient forest, fewer orchards and greater predation. Hawfinches have more wide-ranging territories than most finches, which makes radio-tracking studies difficult but underlines the extent of woodland needed to sustain colonies.
Species action plans have been created by conservationists, but directing resources towards Hawfinch’s recovery is hampered by a lack of long-term empirical knowledge.
This is exacerbated by monitoring being hindered by lack of manpower, under-funding and the species’ secretive nature.
Despite this, many useful records are accounted for in county bird reports, the BTO’s BirdTrack and Cornell’s eBird app, and summarising this data has helped confirm the rapid fall in numbers. It can only be hoped that enough is learnt in enough time to keep this charismatic finch as a robust member of the British breeding avifauna. Certainly, the value of ancient woodland is apparent, and allowing large tranches to mature and become interconnected again, instead of being flattened by projects such as HS2, is the best way to provide further habitat for this most striking finch, along with other ancient woodland species such as Lesser Spotted Woodpecker and Willow Tit. The sedentary habits of our resident Hawfinches mean that a persistent birder can track one down without disturbance, while the occasional irruption provides the chance of an exciting sighting for the ardent patch-watcher. Otherwise, small, temporarily resident winter flocks are often announced on BirdGuides and you can visit one of the regular roosts such as Bedgebury National Pinetum, Kent, or Lynford Arboretum, Norfolk – but watch from a healthy distance!