Another Life: A head start to save our threatened birds?

Michael Viney: Captive breeding of eggs taken from the wild can contribute to our conservation programmes

By this time in autumn, most of Europe’s portly corncrakes have made it back to Africa, to grassland savannahs in the east and south. Among them this year, given any luck, are birds raised from eggs saved from the path of an Irish silage mower.

A farmer on Donegal’s Fanad Peninsula spotted the nest just in time to avoid its 11 eggs. These were rescued by the EU-backed Corncrake Life project, working with farmers in the northwest, and taken to the Fota Wildlife Park in Cork, now practised in captive breeding of rare and endangered species.

Nine of the eggs were hatched and the reared (and ringed) fledglings released at the Donegal farm. Their return migration will be eagerly watched for next spring.

It will help decide if captive breeding of eggs taken from the wild — termed “headstarting” — is to play a part in Irish conservation programmes. Fota has already bred corncrakes from the eggs of captive birds and the Irish Grey Partridge Trust has been practising at incubating eggs and rearing the chicks (to be fed every hour).


In Britain, curlew eggs are now being rescued from airfields and hatched in captivity

Releasing captive-bred chicks would, however, amount to reintroduction of the species, a desperate last resort in conservation. For the National Parks and Wildlife Service (NPWS) this “is not seen as a preferred option at this time”. Corncrakes lay two or even three clutches of eggs in a season, many of which are often lost to predators, so that “rescuing” some for protected, hand-raised breeding is at least a practical idea.

Ireland’s other critically threatened bird is the curlew. It lays only a single clutch of about four speckled eggs and has even more threats to their survival.

In Britain, curlew eggs are now being rescued from airfields and hatched in captivity. The fear that flying curlews could damage aircraft had hitherto prompted their destruction. Dozens of eggs were rescued this year by Natural England and the Wildfowl and Wetlands Trust and the reared fledglings released in safe habitats in Norfolk.

Some of those released there in 2021 were marked and satellite-tagged and one, having flown off to loop the Celtic Sea for 12 hours, landed as a migrant in Co Waterford.

Headstarting has been trialled in Northern Ireland and was used to save three eggs from a predated nest at a traditional curlew site in Co Donegal. They yielded the first chick to be reared in a large pen and released to the wild. The NPWS Birds Unit “continues to consider the feasibility of a curlew headstarting programme”.

In both islands, the ground-nesting curlew is threatened by dismal difficulties in raising young. In Britain, each pair produces, on average, just one fledgling every five years.

In Ireland, breeding curlews are down from some 5,000 pairs in the Republic in the late 1980s to no more than 150 pairs in 2019 — a drop of 96 per cent. Breeding productivity is so low that the curlew could go extinct as a breeding species in Ireland before 2030.

Until last year, breeding populations in the nine breeding areas of the NPWS conservation programme had been relatively stable. But only four of them fledged chicks in 2021. Co Kerry had not seen curlew fledglings in the past four years. Sites from Mayo to Monaghan had similar pictures of nests robbed or abandoned, even when fenced against foxes by a NPWS protection team.

The number of foxes, mink, magpies and hooded crows and buzzards is increasing, notably in landscapes fragmented by conifer forestry, and their predatory lifestyle is still the main cause of the curlews’ breeding failure. Human activity can play a part too, as in spring wildfires that blacken the bogs of Kerry’s Stack’s Mountains.

This remorseless, now urgent, threat can be obscured by the sight of migrant curlews arriving from Europe

The work of the NPWS action teams is now intensive, fencing nesting curlews, controlling avian predators and enlisting the help of farmers. If the birds are not helped to raise enough young, their species must lead to extinction in Ireland.

This remorseless, now urgent, threat can be obscured by the sight of migrant curlews arriving from Europe. One thinks of these as late autumn birds but here on the Mayo coast dozens of early, non-breeding immigrants start arriving at the shore by June or July.

An ornithologist neighbour across the lake, Dr David Cabot, keeps an eye on them through a powerful telescope. In July this year there were 35 standing in a row at high tide “like lead toy soldiers” and by early September 42 were probing the machair, left soft and wet by a spring tide.

There was a time when I could have thought them all our own handsome, home-grown birds, freshly down from the hills. It has been no joy to learn better.