The question of whether the increasing abundance of predators in the British Isles has contributed to catastrophic declines in songbird populations is controversial and highly charged.
An article published in 2010 by Stuart Newson of the British Trust for Ornithology and co-authors appeared to settle the issue once and for all, concluding that “Analyses of large-scale and extensive national monitoring data provides little underlying evidence for large-scale impacts of widespread avian predators and grey squirrels on avian prey populations”.
In the same year I published an article demonstrating a striking correspondence between the spatio-temporal pattern in the late 20th-century recovery of the Sparrowhawk and that in the decline of the House Sparrow, and concluded that this was likely to be a causal relationship. This is contrary to the Newson article, which found no relationship between the two species.
The existence of a close correspondence between Sparrowhawk increase and House Sparrow decline has since been corroborated by an independent analysis of the same Common Birds Census data set. However BTO continues to dismiss such results (see ‘Further information on the causes of change’, accessed 16/7/16), claiming a superior level of sophistication for the Newson study.
My objective in establishing this site is to create a platform for critical discussion of Newson’s article, which is central to the controversy over whether the acknowledged increase in the number of predators in Britain over the past half century has contributed to the decline of songbirds over the same period. It remains the principal authority cited in support of the conclusion that this is not the case, and its significance can therefore be seen in its effect on public policy, which continues to implement conservation measures for songbirds that discount the significance of predators, but which have yet to reverse the decline in songbird populations.
It has also contributed to the rift between the experts and many sections of public opinion, which has seen the rise of groups such as You Forgot the Birds, comprised in large part of disillusioned current and former subscribers to the RSPB. Such popular opinion is easy to dismiss as either simple-minded or sentimental, or else as being in thrall to a sinister cabal of interests seeking a return to Victorian attitudes towards predators. However, there is also reason to distrust experts who, like the rest of us, are born of the crooked timber and therefore prone to seek their own interests. If songbirds have declined because of pollution or farming practices, bird boffins can claim a rent on the public purse while seeking solutions, but not if the decline is merely the downside of increased predator numbers.
Expert peer-review may therefore be lenient towards studies that sustain an approved narrative, and averse towards those that threaten it, and herein lies the answer to the reasonable question: why now? In other words, why did I not unleash my critique of Newson’s offering when it was published, rather than fully six years later? The answer is simply that I didn’t think there was the slightest possibility that the Journal of Applied Ecology would publish it, regardless of the veracity or otherwise of its arguments.
Regrettably, such comfortable resignation is no longer sustainable, since the conclusions of Newson’s study have ossified into a dogma. Evidence to the contrary is now considered flawed by definition, and any study that gainsays its findings is committed to the flames by default. The formalities of peer-review continue to be observed, but when editors and reviewers feel secure within an established orthodoxy their efforts may err towards the perfunctory. It comes as no surprise, therefore, when a journal seeks to parlay its duty of confidentiality towards authors into a similar obligation on the part of authors towards reviewers. Such reciprocity is unwarranted, however, and neither is it desirable, since the prospect of public scrutiny in the event that an author chooses to make his work freely available may be the best possible incentive towards rigour within peer review system.
Here, therefore, I present a critique of Newson’s paper in the form in which it was submitted to the Forum strand of the Journal of Applied Ecology in January 2016. The anonymous evaluations received are published in the accompanying web log, and each is commented with rebuttals to the negative remarks they contain. The critique will be submitted elsewhere with a covering note referring to this site, and notifying the editor that any reviews or other correspondence received will be published and responded to here.
When all the experts agree, the opposite opinion cannot be regarded as certain, and it is entirely possible that part or all of my review of Newson’s paper is misconceived. If this is shown to be the case I will be happy to amend the review accordingly, or indeed to withdraw it altogether should the demonstrated flaws be serious enough. No such demonstration has yet occurred, however, and in this context it is worth noting that in April 2016 I forwarded the review to the British Trust for Ornithology in response to an offer by them to provide comments. I’ve received no response either to this or to subsequent enquiry. I have, however, received a commentary on the review from one of the co-authors of Newson et al., Nicholas Aebischer, and have responded to this along with a request to publish the exchange here. Dr Aebischer has declined this request, and as this refers to personal correspondence I will respect his wishes. However, I invite all of the co-authors, and any other suitably credentialed parties to submit their responses on the web log.