Nature 2017 August

Look out for the return of two top predators

There was a compulsion shared by the gentleman amateur naturalists of the 19th century to collect more species of butterfly, bird’s eggs, fossils, and so on, than their rivals. Large amounts of money often exchanged hands to secure a particularly rare specimen and gentlemen often employed others to search out much sought after examples.

Charles Darwin was an obsessive hunter of beetles and hired men to collect particular specimens that he could add to his collection or trade with his beetle-collecting peers. Lionel Walter Rothschild’s obsession extended to creating a zoo in his back garden and also a purpose-built private museum to house the stuffed birds and animals he purchased from collector/ hunters. A visit to Tring Natural History Museum (NHM) brings us into conflict on the one hand with our fascination with the natural world and our anxiety of enjoying the sight of so many dead animals slaughtered almost for the sole purpose of providing entertainment for the Victorian aristocracy.

I suspect that having seen all the animals and birds on display, relatively few visitors pause by many of the mahogany cabinets to inspect the hundreds of drawers containing insects of every hue and kind. Next time you visit do dally for a moment to look at some of the trays. Not only is the breadth of the insect kingdom represented surprising but also the evidence of how this Victorian obsession took hold of collectors like Darwin and Rothschild as displayed by the examples of the minute variations within a particular species that were also deemed essential to outcompete other collectors.

There are some cabinets tucked away in Tring NHM reserved by the top insect predators, the dragonflies, from the UK and around the world. By the early part of the 20th century all the thirty or so then known resident species of dragon and damselflies had been identfied, named and recorded. Much as is the case today with twitchers descending on a quiet backwater to catch a glimpse of a rarely seen bird blown off-course, so the dragonfly collectors sought out examples of the scarce varieties.

One such was given the name ‘scarce aeshna’. It was described in 1937 as a ‘sometime visitor restricted to the south coast’. Since then it progressively became a more frequent visitor. By the second half of the 20th century, reflecting that it now regularly frequented the southern counties, it was renamed the Migrant Hawker. Soon it had become a resident species and has subsequently spread to most of England, parts of Ireland and, since the year 2000, it has been recorded in Scotland. The Migrant Hawker is just the first example of a trend in UK colonisation by up to fifteen European species that can now survive the increasingly warmer climate in the UK. However, it is not all rosy as a further thirteen UK dragonflies have seen their breeding range recede, partly due to climate and loss of habitat, but also due to competition from other more successful dragonflies.

Look out for larger fat-bodied dragonflies and smaller damselflies on the wing over the summer. The dragonflies which spend most of their time on the wing, protecting a 20 metre territory to hunt for prey, are known as hawkers whilst those that lurk atop stems and dart out to catch their food are the darters. Both rely on their large all-round vision compound eyes comprising up to 28,000 facets per eye which detect small movements and enable depth-sensitive vision.

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In a recent BBC online news article an arresting image of a Eurasian Lynx staring straight back at me certainly was an attention grabber. This was not the expected story about these medium-sized wild cats living in the extensive forests that cover much of Siberia, the boreal forests of the Balkans or amongst the steep slopes in the Carpathian Mountains. Nor was it the illegal trade in skins acquired by hunting parties in Russia, Finland and even Sardinia. This was a story centred on a project much closer to home, in the north-east of England.

At first sight the initial phase of the project sounds like a fairly modest affair involving the introduction of four to six lynx fitted with radio-controlled collars to a monitored reserve within the Kielder Forest in Northumberland. The forest has been selected for its remoteness from human habitation and absence of roads. Unsurprisingly, the main concerns expressed locally about the project are the impact on sheep farming and shooting businesses. Meanwhile one of the arguments for the pilot reintroduction is that lynx control the fox and deer populations but rarely take sheep and shun human contact.

Unlike the wildcat, the only current member of the cat family which has maintained a UK presence in restricted areas of north Wales and the Scottish Highlands, the lynx is not exactly domestic cat sized. Lynx are large (1.3m long) heavy (30 kg) powerful carnivores with intimidating claws and sabre-like incisors. Ten thousand years ago, at the end of the most recent Ice Age, the area that would later become the British Isles emerged from beneath the receding ice sheet. Before the melt water had the opportunity to overwhelm the land bridge with the continent many foraging mammals like voles, shrews, red squirrels, dormice, boar, deer (roe and red) migrated westwards.

Alongside these familiar animals several large predators, such as the lynx followed. At this time much of their territory would have been densely wooded and in a Chiltern landscape with its secret wooded valleys rich in wildlife, but largely empty of humans, the lynx would have thrived. However, although a top predator, the lynx would have needed to compete for its prey with other top predators such as the wolf. The type of territory the average big cat, like a lynx or the mythical panther spotted from time to time locally, needs is a very remote wooded area in excess of 100 square miles. It has been some time since the last lynx died out in these parts, coinciding with the clearance of many forested areas due to the expansion of farming. It was probably around 700 AD when it was finally hunted to extinction over most of England.