Richard Cranmer Dening - a life combining a passion for natural history with colonial life in Africa and travels to exotix places.

To Collect or Not to Collect?
Dr Barbara Corker F.R.E.S.

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The Importance of Habitats

The blame for the extinction of species is often laid at the door of collectors (or hunters). I believe that in most cases this is just a convenient cop out. Given the right habitat conditions and enough food, most species are incredibly resilient. Nature works on massive overproduction of young. Far more than can ever survive (given that there are always limited supplies of food and other resources) are routinely produced. This means that when adult individuals of a species die, they leave a gap quickly filled by a juvenile which would otherwise have died in the competitive rat race of life.

G0442893.WMF (52988 bytes) To illustrate this point, a single female butterfly may lay up to 1,000 eggs in her short life span. Only 0.2% of those eggs needs to survive in order to maintain the butterfly population at its existing level.

If 99% of all those eggs which she lays (or the successive life cycle stages) succumb to the depredations of predators, parasites, collectors, inclement conditions, lack of food and disease, then the butterfly population would still quadruple. This also assumes that a male butterfly is only fertilising one female. In reality, he probably fertilises several, which means that the population’s rate of increase based on these figures is even higher.

However, there is an important caveat here - quick replacement is only possible if the habitat conditions remain suitable and its area does not diminish. Even such apparently insignificant changes as the height of the grass, the amount of shading or a slight rise or fall in the average temperature may make all the difference to the survival or extinction of a population.

A population is a collection of individuals belonging to one species, living in a particular area. A single species is therefore usually made up of a number of populations of individuals living in different locations.

Local populations of a species may become extinct in a particular area without affecting the viability of the whole species. Those species which are very localised (endemic to a particular area) or where there are very few populations left, are most at risk of extinction through habitat loss or environmental change.

 

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Human Population Pressure

The extinction of species is far more attributable to the loss of their natural habitats than to the activities of collectors. As our human populations continue to increase at an exponential rate, more and more natural areas are converted to urban sprawls, industrial complexes and agricultural uses in order to feed, clothe and house us all in the style we like to be accustomed to. As a result, the area of natural habitats is shrinking at an alarming rate. It is this loss of natural habitat which is the real culprit in the extinction equation, with pesticides and pollution adding to the toll.
forager.jpg (41588 bytes) While we have very laudable targets for restoring natural habitats for wildlife in the UK, this restoration comes at the expense of losing areas once given over to intensive agriculture and forestry.

Now, our population is not declining. It is increasing at the rate of a small city a year. All those people need feeding and they need resources such as paper and timber.

I am afraid that while all our restoration efforts may be great for wildlife in the UK, the end result will merely be the decimation of pristine natural areas and wildlife somewhere else in the world. Loss of agricultural production in this country simply means that we export our needs overseas and end up turning natural areas in places like Zambia and Kenya over to intensive agriculture instead. (Take a look at the places of origin on the packets of vegetables in your supermarket next time you are there.)

Collectors as Species Exterminators?

I start this section by stressing that I am limiting my comments to insect collecting, which is the only area where I feel I have enough experience to venture an opinion. I would also make the point that we have been doing our level best to exterminate various pest species for centuries (and perhaps millennia) without having any appreciable effect and in some cases almost losing the battle altogether (witness the success of rats). There also seems to be something of a double standard operating here in that we would quite cheerfully exterminate the pestilential clothes moth, but get upset at the loss of a beautiful butterfly!

In Victorian times, woods were still regularly coppiced for much needed timber products, while intensive agriculture, pesticides and large-scale hedge removal were not yet common practice in the countryside. The extent and quality of available habitats was such that butterfly numbers were high and the populations could sustain really extensive collecting efforts. One collector in the 1820’s, recorded that in the space of half an hour, he had captured over 200 specimens of White-letter Hairstreak butterflies without moving from the spot (1). It is hard to imagine the dancing parade of butterflies which must have existed at that time, to make the collecting of so many individuals possible without any appreciable searching or long drawn out effort.

There have been no collectors in this league for a considerable period of time now (in insect generations at least) but there are still comparatively few butterflies. If collecting had been solely to blame, in its (relative) absence, the numbers would have bounced back long ago.

Approximately a dozen species of butterflies and moths have become extinct in Britain over the last 150 years, with habitat loss as the primary cause. The Large Copper butterfly and several species of moths became extinct because the advent of steam pumps meant that the Fens could be drained, thereby changing the habitat beyond all recognition. Collecting may have been the last straw for one or two already stressed, isolated populations of the Large Blue butterfly, possibly causing local extinctions. However, the Large Blue also became extinct in areas where there was no collecting. The real culprit in this extinction was changes in grazing practice. This meant that the grass became too long for the survival of the ant species on which the caterpillars’ survival in turn depended

I am not advocating a return to the days of indiscriminate collecting. I am merely pointing out that the individuals of a species taken by collectors are in most cases readily (and quickly) replaced. In addition, most adult insects have a relatively short life span anyway. In the case of butterflies and moths, this may be as little as a few days. Within a seasonal time frame, there is also a staggered turn over of adults, as new ones emerge from their pupal or nymphal stages over an extended period. A collector is therefore only ever likely to see a fraction of the total population at any one time.

We can in many cases learn much about the natural history of species by observation alone. However, in the areas of taxonomy, geographical distribution, genetics and evolutionary processes, specimen collecting is often the only way of obtaining valuable and verifiable scientific data. Greater understanding of the life and living processes going on around us, may in the end enable us to ameliorate some of the damage caused by ever increasing demand and competition for space and resources from human populations

Personally, I think the real danger lies not in collecting, but in the current ideology which preaches that the environment is so fragile that we need to put it on a pedestal and say ‘look, but don’t touch’. We are already alienated from the realities of life to an alarming degree. The natural world seems increasingly to be viewed as a kind of animated museum display, locked behind the glass walls of politically correct rules and regulations which address the wrong issues and ignore the real problems.

I owe my love of natural history to my father and the things that he consistently showed me first hand as I grew up. Most of all, he showed me that the natural world is real. It is robust and it changes constantly, with or without us!

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150 years ago the world population was around 1.2 billion. It is now over 6.5 billion (more than 5 times higher) despite massive mortality rates due to Stalin and Hitler's efforts, two world wars, various world wide epidemics, local wars and Third World starvation.                       World Population Figures
 

(1) The Aurelian Legacy: British Butterflies and their Collecters (2000) by The Hon Miriam Rothschild, Michael A. Salmon, Peter Marren, and Basil Harley.

This is a wonderful book with a wealth of interest, which I have used as a source for some of the information in this article. I highly recommend it.

 

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Barbara Corker is part of the team revolutionizing countryside interpretation with Q3 Rangers

 

 

 

Website: Copyright B.Corker 2008