Long-term Camera Trap Survey of Vertebrate Biodiversity in a British Hedgerow (2015-2024)

 

Its taken about six months but I have finally completed writing up my findings from 20 years of camera trapping to record vertebrates on my patch.

I have produced a report to outline the data collected available from the link below:

Long-term Camera Study of Vertebrates

Excerpt from the publication

Over the 10-year study period 54 species of vertebrates were recorded. 31 species of bird, 21 species of mammal and 1 species of reptile (Figure 8). 2 mammal species were removed from analysis these were domestic animals that were recorded, the domestic cat (RAI 0.01) and the domestic dog. (RAI >0.01), and 2 similar species were merged into a single group.

Vertebrate Group	Number of Species recorded in the Study	Number of Species known to have been recorded on the site	Percentage of all species recorded on the site.
Mammal	21	24	87.5
Bird	31	91	34.1
Reptile	1	1	100.0
Amphibian	0	3	0.0
Total	54	119	45.4

In total nearly 50% of all vertebrate species that could be observed on the hedgerow were recorded.

Assumptions made in the data.

It is important to understand the limitations of the survey design and the assumptions that must be made during their interpretation.

·        That all species are equally detectable by the camera.

·        That the species are not discouraged or alarmed by the presence or operation of the camera in a way that changes their behaviour and use of the habitat around the camera.

·        Abundance is only used as a naïve estimate population density.

·        Each 10-minute recording unit is independent of each other.

 

Survey Effort

The survey period ran from the 1^{st of} January 2015 to the 31^{st of} December 2024. Each 24-hour period was divided into 10-minute activation recording blocks resulting in a total of 52,560 such recording units each year and a possible total of 436,752 over the ten-year period.

During the survey there were many camera failures such as batteries running out and file corruptions; and problems with access to the site these resulted in an effective total effort day value of 3033 days. This represents 83% of the ten-year study period that the camera was active and recording (Figure 9). The survey effort resulted in a data set comprising 19,073 10-minute record units containing an individual species.

Modern trail cameras are incredibly reliable and there haven been some significant advances in the technology over the 10-year period as well as considerable reductions in price. In the same fashion the size and quality in digital recording devices (SDHCs) have also improved.  Despite the equipment's general robustness the camera was not recording for 17% of the time and this downtime was primarily a result of human error or intervention. The most frequent cause of an outage was from not switching the camera back on following card swaps, the next most common failure was a power failure due to batteries running flat. Only 20% of lost time was due to an actual fault in the camera or memory card (Figure 10).

Reason for failure	Percentage of all failures
Camera not switched on	26
Camera not in situ (repair/theft)	18
Batteries expired fully	18
Access to site restricted (unable to replace batteries	13
Unknown Camera failure	11
Night vision failed	5
SD card failure (corrupt/lost files)	4
Camera knocked out of alignment	4