Breeding Newts Delay £90m Project

The Monks Cross development in York was planned to open next Christmas but has been delayed until Easter in 2014, due to a "huge" rise in newts on the site.

The population of great crested newts has grown by more than 3,000 per cent, from nine to 300, in December.


I've seen this same story repeated by a number of news outlets recently and it demonstrates the problem that ecologists frequently face when explaining results to clients and the media. 

Problems associated with detectability of a species mean that the number of newts observed during a survey rarely correlates with the population present within a site. The number of animals observed during a survey can depend on a multitude of factors (e.g. water clarity, vegetation, water levels etc). It's much easier to count newts in a pond with clear water than a murky pond full of pond weed. 

The number of newts captured during mitigation work frequently exceeds survey predictions. For example, a mitigation project undertaken by Calumma Ecological Services on behalf of Gallagher in 2012 recorded a maximum count of just 6 adult great crested newts in pre-capture survey work. Yet, detectability issues were clearly present in the overgrown target pond and the EPS Licence application stressed that significantly more animals were likely to be captured. In fact Calumma proposed that as many as 750 newts may be captured. Calumma originally wanted to ring fence the pond and capture animals as they migrated back to the pond. Unfortunately, delays in obtaining the licence meant that works could not begin until after animals had returned to the pond to breed. Capture totals were therefore significantly inflated by high numbers of larvae and metamorphs. In fact more than 2100 newts have been captured at this location and work will need to continue in Spring 2013. The actual number of captured adults (484) and juveniles (24) are currently well within the original prediction of 750. 

If great crested newts (that can take three years to reach sexual maturity) really could increase their populations by 3000% in one year, I think that not only would the laws of physics need re-examining, but conservation work would be a little easier to achieve.