The conservation and heritage charity for the
Loch Lomond and The Trossachs National Park

Weekly Nature Watch

Weekly Nature Watch 09 Aug 2019

on .

Within a few weeks of taking their very first flights, many young birds are thrust into harsh reality, facing what can often be a very hostile world. Therefore, they must quickly learn to become entirely independent of the parents that have so dutifully nurtured them. Even now, a whole new generation of relatively newly fledged birds is already well on the way to staring the danger filled avian life full in the face. Having to become self-sufficient in a matter of days or at best weeks poses many challenges so as a result they naturally find that they are on a very steep learning curve. Finding their own way in the world and learning the real art of survival will challenge them to their limits. There is no escape from the fact that nature is indeed, red in tooth and claw. The freedom these new generations are now beginning to enjoy clearly comes at a price for there are also new generations of newly fledged raptors, which pose a real threat to the survival of many of those juvenile songbirds.

The lack of experience on the part of many young birds plays very much into the hands of young raptors, which, of course, are also facing serious survival challenges albeit, of a rather different nature. Although they have yet to fully assimilate the hunting skills that will guarantee their long-term survival, they must become dependent initially on the vulnerability of young songbirds as they make their way towards self -sufficiency. They are fortunate that so many young, inexperienced quarries are available, which luckily makes their task ostensibly easier. Thus, all new generations, whether the hunted or indeed the hunters, are on that steep learning curve. For one group to survive, some of the others will inevitably have to fall by the wayside.

Young raptors have to be phenomenally fast learners. Failure is not an option, for those unable to take on board the necessary skills of stalking prey, using their natural speed to run fleeing birds down or in some cases, laying ambushes to ensnare their victims, will literally starve. Mortality among young raptors can be surprisingly high, especially during the first winter of their lives. Even during the mildest of winters, many will fail to make it to the following spring. Sparrowhawks and goshawks rely upon all those skills together with a natural athleticism that enables them to navigate their way through woodland where the ability to turn sharply at speed as they pursue prey is so important. These are the vital skills young sparrowhawks and goshawks are currently in the process of honing.

However, this summer does seem to have been especially productive with a plethora of young birds very evident. This will ensure that young sparrowhawks and goshawks get off to a good start in life. However, for kestrels and especially for owls it is small rodents that form the basis of their diet and all the evidence points towards something of a dearth of this kind of prey. This has certainly been manifested in the reduction in numbers of these once extremely familiar raptors. For example, not so many years ago local skies more often than not yielded sightings of hovering kestrels. Now I so rarely see kestrels and how I miss them!

Kestrels and owls and perhaps to a lesser degree, buzzards and the new generation of red kites, generally rely upon good populations of small mammals such as mice and voles as their main sources of food. Whilst numbers of voles regularly fluctuate resulting in ‘good’ or ‘bad’ vole years, there does seem to have been an overall reduction in vole numbers in general over recent years. It may be that a wider use of rodenticides, commonly deployed to control mice and rats, has made an unusually significant impact on all rodents but it would also seems likely that other factors have combined to depress vole numbers in particular. Buzzards and kites of course, supplement their diets by feeding extensively on carrion.

Water voles were once familiar residents of many riverbanks. However, their numbers were decimated many years ago by the arrival of alien mink in the landscape - escapees from mink farms or worse, animals deliberately released by people who protested against the very notion of fur farming. I don’t much like the notion of fur farming either but setting hundreds if not thousands of mink free to decimate local wildlife was frankly an act of crass stupidity. Actions may sometimes speak louder than words but such actions can have a devastating effect on native wildlife. I remember only too well the consequences of one such protest. It was desperately injurious to a wide range of wildlife. Ground nesting birds were slaughtered wholesale and virtually no wildfowl on our local loch produced any young for a year or two. In recent years, much effort has been made to eradicate mink from local rivers and lochs and new populations of water voles have been re-introduced. Let’s hope they prosper!

Field and bank voles, fundamentally prey for the widest possible variety of avian, reptilian and mammal predators, also seem to be in quite serious decline. Hence, a parallel decline over recent years of kestrels. But they are not the only birds to suffer. Owls also rely upon small mammals for their survival. Barn owls have been in serious decline for many years and this is not just a British state of affairs. Right across Europe, Barn owl numbers have reduced alarmingly over many years. The conclusion made by experts suggests that barn owls and modern farming methods do not go well together! Furthermore the more widely distributed tawny owls and those more diurnal moorland predators, the short-eared owls, seem also to be in decline.

There was a time when short-eared owls were a very familiar sight on local moorlands. The spread of more forestry has undoubtedly legislated against them. They used to be a familiar sight, their long wings beating slowly as they coursed low over moorland habitats during daylight hours. New plantations, fenced in order to exclude grazing animals, were soon populated by field voles and so were quickly colonised by short-eared owls. Now I seldom see short-eared owls, even where there are apparently suitable new plantings. Again, this points to an absence of suitable prey, those disappearing voles!

Although nature is generally robust, these declines are worrying. They deplete the amazing diversity we used to enjoy. Instead of robustness, there is suddenly a detectable fragility in the fabric of nature, which seems likely to be connected to the increasingly pervading influence of mankind on the natural world. When you remove some of those vital building blocks, inevitably the whole structure is weakened!

Any natural place contains an infinite reservoir of information, and therefore the potential for inexhaustible new discoveries.

Richard Louv, Last Child in the Woods