Part 5: Interglacial birds

 

Golden Oriole

The avifauna of the British Isles during the Eemian would have been similar to that of today, with the addition of species now more often found further south in Europe as the climate was slightly warmer. We can imagine as well as the current birds of Britain such species as Golden Oriole, Hoopoe, Serin and Melodious Warbler in the woodlands. Some birds such as House Martins, Swallows and Common Swifts that are strongly associated with human houses as nest sites would have been restricted to their original habitat of cliffs and rocky outcrops, but might have been joined by Red-Rumped Swallow.

Red-Rumped Swallow

Birds today that are associated with farmland, such as most of the finches, Skylark, Grey Partridges and Great Bustard would have been using their original habitat of elephant and large ungulate grazed grasslands, and would probably have been less numerous than in modern times (at least before intensive farming after WWII reduced their numbers)

Black Stork

White storks formerly bred in the UK in historic times and are currently the subject of a reintroduction project. As well as these Black Stork must be a strong possibility as a British breeding species. Unlike the sociable and farmland loving White Stork the Black Stork loves woodland and wetland and has a vast range from Spain across to China, migrating south to Africa and India for the winter. Glossy Ibis is another likely resident, as well as many of the various southern herons that have recently begun colonising Britain in response to climate change. The exception to that would be Cattle Egret – it has finally started breeding in the UK but its current worldwide spread is a result of its adaptation to livestock farming, and without that it would have probably stayed further south.

Western Swamphen

Other specialist marshland and reedbed birds would have included Western Swamphen, Zitting Cisticola, Black-necked Stilt, and Penduline Tit. European Cranes are also known, but they might have been joined by a now extinct, even larger species Grus primigenia. This species has been variously placed as just a large form of the extant Eurasian Crane, but might also have been a second crane species – in many parts of the world multiple cranes species live in similar habitats and in east Asia can be found several large species even today, for example, the Siberian Crane. If it was a real species it might have survived as late as the early Roman period, and remains from Malta suggest it might have been a rare migrant to southern Europe.

Mandarin Ducks

Among ducks Ruddy Shelduck is known to have been present – it now occurs only as a vagrant or escape. The Garganey is a small migratory duck that is a very scarce breeder in Britain and Ireland. It prefers to breed on shallow lakes surrounded by grassland, a habitat that elephants and hippos would have helped create. One remote possibility is Mandarin Duck. Although today they are only native to the Far East, either Mandarin or a closely related species is known from a previous interglacial and presumably became extinct as a result of elimination of habitat by ice advances at some point. Today Mandarin is well established as a feral breeding bird in Oak woodland in England and the Eemian interglacial would have provided a very similar habitat.

Dalmatian Pelican

Dalmatian Pelican sounds like an unlikely species for Britain – it is the largest living pelican and today has a distinctly east European/central Asian distribution, but they had a much wider range even in historic times and are known to have bred at several sites in England up to at least the Bronze Age, so it is quite possible they were at least briefly a British breeding resident during the warmest parts of the Eemian, at least until the climate cooled towards the start of the next glaciation.

Capercaillie

Most of Britain’s grouse species are today associated with the north of the island, especially moorland and pine forest. There would probably have been similar extensive forests of pine and birch in many areas holding the world’s largest grouse, the Western Capercaillie, which in the males is turkey sized. Today these amazing birds are only found in the Highlands, and even there they are a rare and declining reintroduced species, having already gone extinct in the UK once, but we have records from the Mesolithic of Capercaillie as far south as Wales. Also present would have been the ancestors of the modern Red Grouse, an endemic subspecies of the circumpolar Willow Grouse which is confined to the British Isles. When the British and Irish Red Grouse developed its distinctive features is hard to determine, but they can live quite happily in Arctic climates, so they probably survived the heights of the last glaciation in southern England while their current Scottish homes were a mile deep in ice.

Corys Shearwater

Two seabirds in addition to those found today would also have been present. The Great Auk is sadly no longer with us, having become finally extinct less than 200 years ago, but it is known to have bred in at least one island off the coast of Scotland in historic times and would have fed in the offshore and inshore waters around Britain. The other species is happily still with us. Corys Shearwater is only a visitor to the waters around Britain today, but remains found in Welsh caves show that it once also bred here.

Lammergeier

Among raptors Kestrel and Red Kite are known to have been present, but it would be very surprising if the other birds of prey found in Britain today were not also present. What is not certain is if any of Europe’s vultures visited or bred in this country. In 2020 a vagrant young Lammergeier from the ongoing reintroduction project in the Alps spent several months in the north of England before returning south. It was well able to look after itself by feeding on carrion and roadkill even in 21^st century England, and both Lammergeier and European Gryphon and Cinereous Vultures are quite capable of surviving European winters where plenty of carrion is available, so it is quite possible that they lived in Britain and fed on the kills of Lions and Hyaenas just as their relatives do in Africa today.

Grey Junglefowl

However, one bird in Britain’s woods would have been very surprising – a wild chicken! Today there are four species of Junglefowl, of which the Red Junglefowl is the ancestor of the domesticated bird. However, the genus seems to have possibly originated in Europe and various species are known throughout the Pleistocene, with the form in western Europe identified as Gallus europeaus. Junglefowl all have very distinctive male plumages, but the life appearance of the British species is of course unknown. Today the nearest ecological equivalent would be Common Pheasant, but this is an introduced species originally native no nearer than the Balkans and without the vast number released each year by the hunting fraternity might not even survive long term as a British breeding species.

Bird fossils are always fragile and many species go unrecorded. Amphibians and reptiles have the same problem only more so, and it is to those I will turn next.