Bat Event in Solar field and Control grasslands sampled in 2024

Description

Series information (English)

The table has 9 variables described below. The levels of the categorical variables are reported in brackets. The range of the numerical variables are reported in brackets. 

• Event_id: unique name of an event (E_1 to E_165724)
• Plot: The combination of the location, plot type and year (2024). 
• Location: The general six areas comprise three plot types. Every location has a unique 2-letter code (AA, AD, MA, OO, RO, TH)
• Type: The plot types are either a solar park (PARK), an extensive control (EXT) or an intensive control (INT). All locations had the three plot types except location TH, which only had the extensive control and the solar park plot type  
• Species: Seven species or genus were included in the study (E.serotinus, Myotis sp., N.noctula, P.nathusii, P.pipistrellus, P.pygmaus, Plecotus sp.)
• Event_start: Beginning date and time of the unique event in the format Year-Month-Day Hour: Minute: Seconds (2024-04-01 16:41:52 to 2024-12-02 19:25:14)
• Event_end: Enddate and time of the unique event in the format Year-Month-Day Hour: Minute: Seconds (2024-12-02 19:25:14 to 2024-12-02 19:25:20)
• Latitude: Latitude of the Plot, but not the exact location of the detector (51.50887 to 53.1505)
• Longitude: Longitude of the Plot, but not the exact location of the detector (4.171396 to 6.357918)

Methods (English)

A block-plot design was implemented at seven locations to evaluate the impact of solar fields on bat species diversity, presence and activity in the Netherlands. In each location, three plots were surveyed: a solar field and two grassland controls. The two controls were an intensively managed grassland for dairy production (INT and an extensively managed meadow for nature conservation (EXT). The controls were located between two and ten kilometres from the solar fields. Each plot was located in the agricultural landscape, meaning that the matrix surrounding each plot was dominated by farmland. Authorisation to place the detector and visit each plot was granted by their owners. 

In each plot, a stand-alone bat detector (Anabat Swift, www.titley-scientific.com) equipped with an omnidirectional microphone (US-O V3 [10 – 140 kHz], www.titley-scientific.com) was placed from April to November in 2024. The detectors were set up to automatically start recording 30 mins before sunset until 30 mins after sunrise in full spectrum. The detectors were placed on poles or trees at the edge of the plots at a height of two meters above the ground.

Sound files were analysed in two steps. First, automated identification was performed by Kaleidoscope Pro using the European classifier with a conservative threshold. All Myotis and Plecotus species were also reclassified under Myotis spp. and Plecotus spp. respectively, as they are known to be difficult to discriminate based on their echolocation.  Species or noise that could not be identified by the classifier were manually processed using Anabat Insight. Only Pipistrellus nathusii, Pipistrellus pipistrellus, Pipistrellus pygmaeus, Nyctalus noctula, and Eptesicus serotinus species, as well as Myotis spp. and Plecotus spp. were considered in this second classification phase. 

Bat calls were then resampled into events. An event was defined as a cluster of calls from the same species less than three seconds apart.