A model of population wasn't realised until early 2010 when photographers suddenly began seeing lots of boar, especially mothers with piglets. It seemed that now everyone was getting photos, whereas pre-2010 it was very definitely a difficult task. Sightings dropped again by the summer, then late in 2010 and early 2011, something very strange started occurring. Roadside were being grubbed up like never before and piglets were everywhere. How had we gone from low numbers of sightings in 2009, with just a modicum of roadside grubbing, to what we were witnessing in early 2011?
The Forestry Commission pounced on this and became ever more insistent that numbers were rising. They began to cite the roadsides as evidence, as well as begin to publicise cull figures:
April 2008 - April 2009 = 38 animals,
April 2009 - April 2010 = 62 animals,
April 2010 - April 2011 = 122 animals
These were published in the proposed 2011 Management plan along with definitive and unquestionable population numbers. What was interesting was that the numbers culled each year became harder and harder to achieve, until in 2011 the FC announced that they had not achieved their target (150 animals).
Targets were simply calculated by subtracting 90 (a number that the Council wanted to survive) from the FC's total population figure.
On first glance it may appear that increasing numbers of culled boar meant an increasing population. This also tallied with the ease at which photographers were tracking down the boar from 2010, especially at certain times of year. But this didn't make sense when the FC could not achieve their cull targets despite the ever rising estimates of total boar - now put at 350 and probably more. By April 2011 they had killed 122 boars leaving 228 and probably more still roaming. But 228 boar was about the population size estimated for the previous year (2010) when the FC managed to cull 1 in 4 boar (62/250).
It all became clear when Friends of the Boar were given, via freedom of Information requests, the cull data from the Castlemain depot - the only larder to take culled boar in the Forest of Dean.
|Wild Boar cull data 2008 - mid 2011. Click to enlarge.|
This was the linear trend. The best fit regression line (shown in red), which tracks some seasonality, predicted even worse to come with a dramatic fall off at the end of the line.
This data was seen by hunting organisations and journalists, with the Guardian in particular very interested. They contacted scientists and boar experts for their input, with the opinion being that the management of the boar was dangerously flawed and culling is being based upon a poor guess at population. Many hunters were also outraged at what was occuring.
Our hypothesis was that the FC were now in their second year (at least) of over-culling. Not by a little bit but decimated by a large margin, which accounted for seasonal difficulties in seeing any boar.
One problem inherent with over-culling, and the more rapid the worse it is, is the population rebound theory put forward by many mammal ecologists. It states that sudden increases in nutrition favour stronger mothers and healthier young - youngsters more likely to survive any hardship early in life (cold weather and starvation produce high mortality in natural systems). What is more, some mammals seem to react to stressful depopulation by actually producing more young in a drastic effort to compensate, and often overcompensate, for the sudden loss of friends and family. Also, when their young are killed, mothers can come straight back into season to produce yet more young! Hunting can create a vicious cycle, and promotes the problem that hunting often proposes to solve - over-population. It is a hunters dream!
The above graph was worrying and we awaited further data to see if the hypothesis remained true.
|Wild Boar cull data 2008 - Sept 2011. Click to enlarge.|
Another conclusion is that the sudden increase in sightings of boar from early 2010 onwards was not a product of more boar, but increasing numbers of sows and their pigets becoming less inclined to run away. These sows were probably young orphans left to fend alone after their mother was shot. From 2004 to mid 2009, sighting of little piglets was very rare indeed. Young mothers were slowly, but surely, created via the compensatory rebound mechanism (earlier fertility) and couldn't pass on any experience to their piglets to run from people (and/or become nocturnal) because there had not been enough time for their own mother to drill this survival strategy home. This is a trend that has continued to this day. Why? Because the FC continue to slaughter mothers and young piglets (evidenced in graph, especially for 2011), leaving any surviving piglets to die, or if lucky and fit (which they are in the rebound model), the piglets grow up with little experience of how some humans love to inflict fear and suffering upon wildlife. This is something that Defra does not give guidance on.