Over the past few years, RSPB, with funding from NatureScot, has been successfully controlling the invasive Spartina cord-grass from the Dingwall Bay area, helping to improve the condition of the sensitive coastal habitats, and in turn improve opportunities for the wintering waterbirds of the Cromarty Firth.

First thought to have been introduced to Dingwall Bay in 1932, Spartina anglica is an invasive species found in coastal habitats and is classified as a ‘high risk’ species on the UK TAG Alien Species Group list. Its presence has contributed to the unfavourable condition of the Cromarty Firth Site of Special Scientific Interest (SSSI), designated for its wintering birds and coastal habitats, and its spread is thought to have had a detrimental impact on the ability of the intertidal areas to support the bird interests of the Cromarty Firth Special Protection Area (SPA). The Cromarty Firth is internationally important for wintering waterbirds, with an average of 30,000 birds present over the winter months.

Large and small scale maps of the treatment area.

Spartina causes problems for the coastal features of Dingwall Bay, saltmarshes and mudflats, in two ways; it occupies ecological space that would otherwise be available to native saltmarsh and mudflat plants, and the tall nature of the grass means that wintering waterbirds are unable to use the areas occupied by the Spartina for roosting or feeding. Waterbirds cannot stand on it and it also reduces visibility, meaning that birds cannot be vigilant for predators.

Spartina can be controlled through spraying with herbicide, which takes place in July or August while the plant is actively growing but before seed heads are formed. Ideally, the herbicide is applied three separate times during this period and then over a number of consecutive years in order to fully kill the plant.

Mature Spartina stand (L) and Spartina amongst sea plantain (R) – (C)David Tompkins RSPB

NatureScot has been funding RSPB to carry out control of Spartina at two problem locations in Dingwall Bay, with support from Network Rail and under licence by SEPA, for five years. RSPB already carries out control of Spartina at their own reserves at Udale Bay and Nigg Bay in the Cromarty Firth, but the existence of another Spartina seed source at Dingwall Bay will always present a potential threat to the good work being carried out elsewhere should it not also be controlled.

During 2019, RSPB was successful in being awarded funding from the EU LIFE programme for the ‘100% for Nature’ project, which includes various actions to achieve favourable condition across a range of sites. One of these actions is to continue to the Spartina spraying programme at Dingwall Bay, in addition to continued control at RSPB Nigg and Udale Bay reserves, all within the wider Cromarty Firth SPA for the term of the project. As part of this, RSPB have employed a project officer based with the Central Highland Reserves team, who will lead on this work for the next few years.

Spartina seedling (L) and seedhead (R), (C)David Tompkins RSPB.

The project officer started their post in March 2020 and progress has already been made in producing a leaflet and poster to highlight the threat of Spartina. Although spraying in 2020 was delayed and restricted by Covid-19, the site team have successfully sprayed all of the treatment areas three times this summer. The aim is to annually treat approximately 100ha of habitat with Spartina until 2024, or sooner if eradication is achieved earlier. Repeat interventions will be carried out to keep any treated areas under control, and ensure that they stay Spartina free.