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.
The survey
period ran from the 1st of January 2015 to the 31st 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 |
