Auchnerran: game and songbird counts in 2018

Scottish demonstration farm - Auchnerran

Auchnerran: game and songbird counts

Thrushes such as blackbirds are thriving at Auchnerran. © Marlies Nicolai/GWCT

BACKGROUND We have been monitoring game and wildlife at the Game & Wildlife Scottish Demonstration Farm, Auchnerran (GWSDF) since early 2015 when we took over the tenancy. 2015 and 2016 were our baseline years: changes to farm management were kept to a minimum to allow extensive monitoring to determine the variety and abundance of wildlife present before we began to make changes to the farm (see Review of 2016). This showed that the farm supported a wide diversity of wildlife, much of it at high densities. This almost certainly resulted from the historical low-intensity farming and high level of predator control conducted over the area. Core monitoring is now more focused on key species and groups to help illustrate how wildlife responds to management changes on the farm.

Lapwing breeding numbers are increasing despite the management of some grass fields. © GWCT

Conditions at GWSDF Auchnerran were challenging this year, with a late very cold spring (the ‘beast from the east’) followed swiftly by an unusually dry spring and summer. This created problems across the farm (see pages 24-25 for our farming summary), but also meant that our routine fieldwork monitoring the biodiversity on the farm was largely unimpeded this year.

One of the first tasks Marlies Nicolai and the team face in spring is counting our game species. At Auchnerran this means searching mainly for pheasants and brown hares, while keeping an eye open for partridges and black game (which lek just up the hill from the farm). Grey partridges are scarce in the Howe of Cromar (the area that Auchnerran sits within), while red-legged partridges are released nearby and drift onto the farm quite frequently in small numbers. This year’s counts suggest that our pheasant numbers have probably stabilised after a period of decline since our tenancy began (see Table 1). This follows the steady loss of the huge number of residual released birds we inherited and suggests that our modest population might now be self-sustaining – good news for Merlin Becker who runs the farm’s small shoot, as is the increase in brown hares this year.

Following hot on the heels of the game counts is our wader monitoring. From March/April, when the weather allows, we try to identify wader breeding territories, nesting attempts and how successful these are. This is a difficult task because with around 70 pairs of lapwing alone breeding on site (see Table 2), it is hard to keep up with them all, especially when first clutches fail and are replaced, and when chicks start to hatch and wander about. We are all very aware of how lucky we are to have this ‘problem’.

In 2018 lapwing continued to increase in abundance at Auchnerran, whereas we recorded the first declines for the other three species monitored (see Table 2). Not only are lapwing breeding numbers steadily increasing, despite changes to the management of some grass fields where the birds breed, but they have also begun wintering on site. The birds move away in response to bad weather (we do not yet

TABLE 1

Game densities (individuals/100 ha) at Auchnerran

Species 2015 2016 2017 2018

Spring Autumn Spring Autumn Spring Autumn Spring Autumn

Pheasant, male 24.3 42.0 22.7 9.4 19.0 18.8 18.4 11.8 Pheasant, female 14.4 25.2 5.8 0.4 4.6 9.4 1.5 10.8 Black grouse 0.4 0 0.4 0 0 0 0 0 Red-legged partridge 0 3.1 1.3 0 0.9 1.0 0 2.7 Grey partridge 0 0 0 0 0 0 0 0 Brown hare 3.7 1.0 1.7 0.2 1.4 0 2.5 4.8

TABLE 2

Wader pair density at Auchnerran per 100 hectares. Data for woodcock are numbers of roding males

2015 2016 2017 2018 Pairs % change Pairs % change Pairs % change Pairs % change

Lapwing* 12.9 - 19.4 51 25.9 34 33.3 29 Oystercatcher* 7.8 - 17.7 127 19.8 12 15 -25 Curlew 2.5 - 3.8 50 4.2 11 3.8 -10 Woodcock - - 4.3 - 6.2 44 5.5 -11 * Lapwing and oystercatcher densities indicate GWSDF is a key site for these species in Scotland (O’Brien & Bainbridge 2002). Note the different summary for woodcock.

know where they go at these times) but move quickly back – and more than 300 birds were counted on the farm in winter 2018. We are hoping to explore this in more detail in future by colour-ringing birds breeding on site and following their movements.

Despite the dry conditions, chick production by lapwing and curlew was still relatively high (see Table 3). The low productivity of oystercatchers reflects an apparent high proportion of birds that don’t appear to breed (so we have lots of pairs, but few nests and therefore chicks). This is another feature that we hope to explore in more detail next year.

Another group of birds that we put extra monitoring effort into is the thrushes. Blackbirds, song and mistle thrushes are present at relatively high abundance, and with support from SongBird Survival, we began investigating why this might be. With the help of Minna Ots, one of our placement students from Southampton University, we began following breeding attempts and the foraging behaviour of adults. Minna found that, rather like the waders, productivity at GWSDF is good with relatively low rates of predation, which averaged 63% at Auchnerran versus 83% on other farmland sites nearby. Our future work will include exploring what adult thrushes eat on the farm and in which fields.

KEY FINDINGS Despite challenging weather conditions, pheasant and brown hare numbers were up or stable in 2018 relative to 2017. Numbers of breeding lapwing were up 29% on 2017 and this species has begun partially wintering on site. Breeding numbers of curlew, oystercatcher and woodcock declined relative to 2017. Overall wader productivity was probably sufficiently high to at least maintain a stable population.

Dave Parish Marlies Nicolai

TABLE 3

Wader productivity (fledged chicks per pair) at GWSDF Auchnerran

2017 2018

Lapwing 1.3 0.9 Curlew 0.9 0.9 Oystercatcher 0.3 0.4

ACKNOWLEDGEMENTS Thank you to SongBird Survival who support our research on thrushes at GWSDF Auchnerran.

(Left) Curlew chick. (Below) Mistle thrush brood. © Marlies Nicolai/Minna Ots/GWCT