Red kite recovery in north Scotland put in jeopardy by illegal killing

Red kite numbers on Scotland's Black Isle have been severely hampered by illegal killing of kites. Photo copyright RSPB

Chilterns Vs Black Isle
It compares the performance of two red kite populations where equal numbers of young birds were released over the same period as part of the initial phase of reintroducing the species in Scotland and England. The sites were in the Chiltern Hills, in Buckinghamshire in southern England, and the Black Isle, in Ross-shire, in north Scotland.

Chilterns kites thriving
Whilst the population in the Chilterns has thrived, reaching approximately 320 breeding pairs since the beginning of the reintroduction in 1989 up until 2006, the Black Isle population has struggled, reaching just 41 pairs over the same period. This was much lower than expected, and the population in 2009 had still only reached 49 breeding pairs.

This graph shows the actual population trend (blue line) for north Scotland and the modelled trend for north Scotland in the absence of illegal killing (red line).  The Black Isle was the location of the first red kite reintroduction programme in Scotland starting in 1989, and yet the population growth and range expansion of red kites in this area, since initial releases, has been far lower in comparison to other release areas across Scotland and the other parts of the United Kingdom.

This large and growing disparity in population sizes has raised concerns, leading some to suspect that the same human persecution that first drove the species to extinction in Scotland in the 1870s is still occurring today.

Close monitoring of both of the study populations showed that production of successfully reared and fledged red kite chicks was very similar in north Scotland and the Chilterns, and indeed was amongst the highest in Europe. Thus, lack of food supply and poor breeding performance does not explain the poor growth rate of the Scottish Black Isle population.

Illegal killing the overriding reason
In fact, the study has shown that low survival rates of young birds in their first and second years of life is the main factor limiting the north Scotland red kite population growth up until 2006, and that illegal killing accounts almost entirely for these poor survival prospects. Red kites in Scotland and England normally breed for the first time in their second, or more normally their third, year of life, so illegal killing is severely reducing the number of new recruits of breeding birds into the north Scotland red kite population.

In the absence of illegal killing, scientific modelling has shown that annual survival rates of young kites would have been high enough to allow the north Scotland red kite population to grow at the same rate as seen in the Chilterns and, by 2006, north Scotland would have held over 300 breeding pairs - 250 pairs more than the actual population size today. More encouragingly, if illegal killing were to cease, then the population is likely to respond quickly, reaching 300 breeding pairs within the next 10 years.

Red Kite reintroduction
The red kite was previously driven to extinction in the late Nineteenth Century in Scotland by widespread human persecution, despite the fact that the species poses no threat to legitimate land use activities. Red kites have been reintroduced to the UK since the late 1980s, but between 1989 and 2009, 64 individuals have been found illegally poisoned in Scotland. The true number of birds killed in this way will be much higher given that this criminal activity largely takes place in remote areas and the perpetrators will seek to conceal their actions from the authorities.

Duncan Orr-Ewing, Head of Species and Land Management at RSPB Scotland, said: "We now have a significant body of evidence to show what a major impact illegal poisoning is having on the populations of iconic birds such as the red kite. More widely, the reputation of Scotland as a country that values its wildlife is at stake. It is time to look again at the range of sanctions and penalties that can be deployed to tackle this damaging activity and bring the perpetrators to justice.

The study, conducted by RSPB Scotland and funded by Scottish Natural Heritage, is published in the scientific journal Biological Conservation.