Species monitoring on the reserve

 Species monitoring on the reserve

The winter months see our volunteer team working hard to maintain the different habitats across the reserve, whether it's removing diseased trees, planting new saplings or rejuvenating tern islands. From the middle of March habitat work has to cease as the breeding and nesting season starts in full swing with many of the woodland species building and using nests within a metre of the ground. Any habitat work would cause too much disturbance to our breeding species.

The focus therefore shifts to monitoring the variety of species that use the range of habitats that we manage. This is essential work as these surveys provide us with the information that is needed to decide which areas of the reserve need attention in terms of habitat management in the following or successive winters, it is the reason that we work hard all winter!

The staff, supported greatly by the volunteer team carry out a range of monitoring projects, the first of which starts in mid March. This is the breeding bird survey. The site is spilt into eight compartments and each volunteer is assigned one section which is then visited four times, once per month up to the end of June. Following guidelines set up by the British Trust for Ornithology (BTO)  and with a few localised adjustments, each surveyor notes down every species of bird and their behaviour in approximately a two hour window around 6am, often using their expert knowledge of bird song and call to identify the species. These surveys are then mapped at the end of the breeding season to highlight the number and diversity of breeding birds across the site. Last year 62 species were confirmed to be holding breeding territories, 7 of which are red listed on the list of conservation concern and 25 species that are amber listed, as well as three species that are Schedule 1 species. This work took over 60 hours of volunteer and staff time. The 2024 survey showed an increase in breeding territories being held by 51 out of the 62 species when compared with the previous year.

Breeding bird survey takes place shortly after dawn

Another volunteer team helps the site to monitor the 144 nestboxes that are situated around the reserve. Of these there are 7 Tawny owl and 3 Barn owl boxes. Again, following BTO guidelines and contributing to the BTO nestbox recording scheme, the team regularly check and monitor the use of the boxes. An endoscope is often used to check inside the boxes as this causes less disturbance particularly if an adult bird is sitting on eggs. At the time of writing 58% of all the woodland nestboxes have showed signs of being used. The team monitor each box every fortnight, checking the contents for nesting material, presence of adult birds, presence of eggs and then nestlings. Great tits and Blue tits are the species that use the nestboxes with the occasional wren making use of a box. When owl boxes are checked the team collect any owl pellets that are present and have been sending them off to the British Mammal Society as part of their "Searching for Shrews" project which is using the contents of owl pellets to determine the presence and impact of the Great white toothed shrew in different parts of the UK.

Blue tit nestlings

Monitoring nestboxes using an endoscope

Alongside the breeding bird survey and the nestbox scheme, yet another volunteer team are involved in a Constant Effort Site (CES) ringing programme. This is a scheme that began at the reserve in 2009 and is the only CES site in the Tophill Low area. The scheme comprises a layout of mist nets that catch birds in the area around south scrub. This project, again one set up by the BTO means that the nets are in place every 10 days from late April through to August, hopefully recording breeding birds that return to the same breeding sites every year. The CES scheme is part of a national project to monitor productivity and survival rates of breeding birds in different habitats. Just this week a Willow Warbler was retrapped, it had hatched at Tophill Low in 2021, returning to the site after making an incredible ten trips across the Sahara in that time, an amazing achievement for a bird that weighs just over 9g!

Garden warbler caught during the CES ringing scheme

Birds aside, there are other species that require monitoring so that the site team can make decisions in terms of habitat management. At the beginning of April our butterfly monitoring team started to walk their transects recording the butterflies that they encountered along the way. The UK Butterfly Monitoring Scheme didates that each transect should be walked once a week in the correct weather conditions, which are in temperatures above 13 degrees and with no rain, making the window of opportunity to carry out this survey quite restricting in our British climate. Each butterfly is identified and recorded and the sightings are sent to the county recorder for their annual report. A workshop was held this year to help volunteers get to grips with the identification of certain species that can be quite hard to distinguish especially when they fly past and don't land.

Marbled white on thistles in north scrub

As well as the butterflies, the grass snakes are also monitored, a survey that was carried out by John Pemberton this morning. He lays out a number of metal sheets (20) in various places around the reserve hoping to entice grass snakes to use them to warm themselves up before they head out onto the reserve to feed. The sheets are checked monthly between March to June and then twice between September to November. This new reptile survey was established as part of the National Reptile Monitoring scheme which is co-ordinated by the Amphibian and Reptile Conservation Trust.

Grass snake by Roy Lyon

All our monitoring and survey work depends on the dedication and support of the volunteers that give up their time to carry out these surveys. The site team owe a massive thanks to all their hard work during the monitoring season as this information plays such a pivotal part in the planning and maintaining of the reserve.