After the 2020 Hope Farm summer monitoring season was postponed due to the Covid-19 pandemic, it has been great to get a full season of biological monitoring completed this summer. In this blog Derek Gruar, Senior Research Assistant, will present our findings from the core monitoring of breeding birds, butterflies and bumblebees on RSPB Hope Farm.
The first few surveys were conducted in unseasonably cold weather; overnight snow greeted early arriving migrants in mid-April. On Hope Farm, we use the Common Bird Census methods to monitor our breeding bird populations. This entailed me having 20 very early mornings (half the farm is surveyed each morning) to cover the whole farm for 10 survey visits between the end of March and early July.
A particularly cold morning © Derek Gruar
492 territories of 44 species were recorded this summer compared to 301 territories of 35 species in 2000. 14 of the 17 Hope Farm Breeding Bird Index species held territories (see table below).
Territory numbers of Hope Farm Breeding Bird Index species 2021.
No. Territories 2000
No. Territories 2021
Kestrel
0
2
Jackdaw
5
Grey Partridge
4
Starling
3
16
Lapwing
Greenfinch
18
6
Stock Dove
Goldfinch
14
Woodpigeon
33
55
Linnet
22
Turtle Dove
Yellowhammer
26
Skylark
10
32
Reed Bunting
8
Yellow Wagtail
Corn Bunting
Whitethroat
25
31
Lapwings nested again for the 5th consecutive year, utilising our agri-environment scheme Lapwing plot. Skylark, Linnet and Yellowhammer were all recorded at levels comparable to those recorded over the past 5 years. Two species held territory for the first time these being Greylag Goose and Red Kite, the latter a species that has gone from scarce visitor to almost daily sightings over the past decade. 61 species have now been recorded as territorial on Hope Farm.
The Hope Farm Breeding Bird Index 2001-2021 now stands as 2.43 (a 143% increase on baseline).
Butterflies at the farm
Three UK Butterfly Monitoring Scheme transects were surveyed for 20th year at Hope Farm, with data submitted to Butterfly Conservation. The first survey on 20th April was later than usual, due to the weather in the first few weeks of the survey season not being up to the minimum requirements to permit a valid survey. The final survey was on 24th September, with 22 of the 26 weekly surveys completed covering over 125km of transect. A total of over 4300 butterflies of 23 species were recorded.
Speckled Wood © Derek Gruar
Comma, Gatekeeper and Small Heath were all recorded at record levels on monitoring transects in 2021. The latter continuing its colonisation of the farm at a rapid rate.
Unsurprisingly with the poor early season weather, Orange-tip were recorded in low numbers. Blues were at their lowest level since 2014 and Skippers also had a very poor year.
At Hope Farm, with the provision of a mixture of grass and floristically enhanced field margins most species were resilient to the poor weather and the Hope Farm Butterfly Index is still well above baseline and now stands at 2.94 (194% increase) a drop from the record year in 2019. However, the trend for butterfly populations on Hope Farm is one of continued growth - see the graph below.
Hope Farm Butterfly Index 2001-2021
Bumblebees
Four Bumblebee Conservation Trust BeeWalk surveys were conducted on Hope Farm and a neighbouring control farm between April and August. At peak season bumblebees were 9.5 times more numerous on Hope Farm than our nearby control farm. This equates to a bumblebee being recorded every 24m of transect walked on Hope Farm compared to one every 225m on the control farm.
Comparison of number of Bumblebees per 100m of transect at peak season between RSPB Hope Farm and control farm.
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