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Seabird Demography: Density dependence and age at first breeding

Seabird demography has been shown to be density dependent in many ways but a new paper by Professor Bob Furness has revealed a link between seabird population growth rate and the age of first breeding.


The paper - Density dependence in seabirds: Great Skuas Stercorarius skua start to breed at a younger age when conditions are better - is based on decades-long research carried out on Foula, west of Shetland. This included the cohort colour ringing of Great Skua chicks and the trapping of immatures and nesting adults, with the result that, overall, a significant proportion of the birds studied were of known age.


According to Professor Furness, principal ornithologist at MacArthur Green, the results revealed considerable individual variation in the age of first breeding, depending on the body condition of the birds in question, but several trends were evident:


·         In smaller colonies of Great Skuas, breeding began at an earlier age than on Foula;

·         A deterioration in conditions on Foula resulted in an increase in the age of first breeding.


“Modelling indicates that an increase in the age of first breeding of one year would decrease population growth rate by about 1% per annum,” says the paper.


It suggests that further study, on other seabird species, may be worthwhile. 


For more information, please read:



NERC CASE Studentship for a PhD study

MacArthur Green and Glasgow University have been successful in winning a NERC studentship to model the impacts of marine renewables on seabird populations. Britain has become the world leader in offshore renewables, and also holds internationally important populations of many seabird species. This project will address the urgent need for a tool assessing direct and indirect impacts of renewables on seabirds, assisting developers and regulators in resolving this important human-wildlife conflict. We are looking for an excellent student interested in a career at the interface between spatial and population ecology. The ideal applicant will have an aptitude for quantitative methods and experience in ecology, spatial statistics or mathematical modelling. Applications (via Glasgow University) are due by 6 February 2015.

Further details are at

The Judges Award goes to MacArthur Green!

MacArthur Green won The Judges Award last night at the prestigious Scottish Green Energy Awards 2014. This accolade is in recognition of the company’s contribution to the renewable energy industry.


Company director David MacArthur said he was delighted by the news of the award. “We have had a great few years, and I feel this is fantastic affirmation that our team of ecology and ornithology specialists are widely respected for their knowledge and professionalism.”

MacArthur Green has had a solid five years of growth, and has acted as a key adviser in some highly notable renewable energy projects. We have also been involved in the production of key guidance documents for the marine and offshore sectors and statutory.

As David said on the night, none of this would be possible without our terrific team and clients.

Our sincere thanks go to the judges.

Collision Risk to Birds Migrating through Offshore Wind Farms

There has been a spate of renewable energy reports published recently. Here’s another one that MacArthur Green had a hand in creating – a report on the ‘Strategic assessment of collision risk to birds migrating through Scottish offshore wind farms’.

The results of this report indicate that for most seabird species and all terrestrial species collision risk on migration is small and very unlikely to be significant. This result will be of great use to those involved in large-scale indicative strategic assessments of offshore wind farm developments.

Commissioned by Marine Scotland, the report is the result of a joint project by the Wildfowl & Wetlands Trust and MacArthur Green and, as the title suggests, was designed to “develop a series of strategic assessments of the collision risks to migrating bird species, and of the components of that risk arising from Scottish offshore wind farms.”

Particular aims of the study were to:

·         “Identify the contributions of Scottish offshore wind farms currently proposed or operational at the strategic level to assess the collision risk to migrating bird species; and

·         identify which populations of migratory birds could be at significant risk from potential collisions with turbines while on migration.”

The first task was to identify the species at risk. MacArthur Green undertook this for seabirds and summarised the populations and migration routes for each species identified.

Once data for both seabirds and terrestrial species (produced by WWT) was collated, MacArthur Green developed the strategic collision modelling, taking into account all of the Scottish offshore wind farms which each species was predicted to encounter on migration. In total 65 species were assessed – 27 seabird species and 38 terrestrial species.

A copy of the report is available here.