267
This exercise generated an additional 1737 birds, bringing the estimated total in the
image to 11,117. This means that the automatic count underestimated the number of
birds in the flock by at least 18.5%, though this still compares favourably with the
median of −57% recorded by experienced ornithologists. In reality, the revised total
of 11,117 birds is also likely to be an underestimate, but a less significant one and
probably by fewer than 500 birds.
It is possible, of course, to undertake a full validation of the number of birds in
the image by carrying out a manual count, but this would be a demanding and time
consuming process that would render the automatic count pointless.
An Automatic Count of Wintering Greater Flamingos
(Phoenicopterus roseus) in Flight over Doñana NP
in South- West Spain
The image used in this case study was taken from a light aircraft (a four-seater
Cessna) in March 2014. The image shows a flock of Greater Flamingos in flight
over Doñana NP in south-west Spain. Despite the different tones in the background
of the image, it was possible to neutralise these using the threshold settings given in
the Text Box 3.
Although the image in Fig. 2 shows spacing between many of the flamingos in
flight, the estimate generated by the automatic count was 871 birds: an underestimate of c. 10% compared to the manual count of 969. This suggests that c. 10% of
the birds in the image were overlapping, though probably more because of the vertical perspective of the image than because the birds were particularly close together.
In practice, a manual count in ImageJ is most appropriate for this type of bird
flock, as it would take only c. 20 min to complete and should be c. 99–100% accurate (Figs. 12 and 13).
An Automatic Count of Wintering Greater Flamingos
(Phoenicopterus roseus) Feeding in a Lagoon at Doñana NP
in Andalucia, Spain
The image of Greater Flamingos feeding in a lagoon at Doñana NP (Fig. 14) was
taken in from a light aircraft (a four-seat Cessna) in March 2014. Text Box 4 outlines the process and settings used to carry out an automatic count of the feeding
flamingos in Fig. 14.
The relatively plain background of standing water and the feeding spaces
between individual birds made this image equally suitable for an automatic or
manual count. This was reflected in the results from the two counts, with the autoImproving the Accuracy of Bird Counts Using Manual and Automated Counts…
This exercise generated an additional 1737 birds, bringing the estimated total in the
image to 11,117. This means that the automatic count underestimated the number of
birds in the flock by at least 18.5%, though this still compares favourably with the
median of −57% recorded by experienced ornithologists. In reality, the revised total
of 11,117 birds is also likely to be an underestimate, but a less significant one and
probably by fewer than 500 birds.
It is possible, of course, to undertake a full validation of the number of birds in
the image by carrying out a manual count, but this would be a demanding and time
consuming process that would render the automatic count pointless.
An Automatic Count of Wintering Greater Flamingos
(Phoenicopterus roseus) in Flight over Doñana NP
in South- West Spain
The image used in this case study was taken from a light aircraft (a four-seater
Cessna) in March 2014. The image shows a flock of Greater Flamingos in flight
over Doñana NP in south-west Spain. Despite the different tones in the background
of the image, it was possible to neutralise these using the threshold settings given in
the Text Box 3.
Although the image in Fig. 2 shows spacing between many of the flamingos in
flight, the estimate generated by the automatic count was 871 birds: an underestimate of c. 10% compared to the manual count of 969. This suggests that c. 10% of
the birds in the image were overlapping, though probably more because of the vertical perspective of the image than because the birds were particularly close together.
In practice, a manual count in ImageJ is most appropriate for this type of bird
flock, as it would take only c. 20 min to complete and should be c. 99–100% accurate (Figs. 12 and 13).
An Automatic Count of Wintering Greater Flamingos
(Phoenicopterus roseus) Feeding in a Lagoon at Doñana NP
in Andalucia, Spain
The image of Greater Flamingos feeding in a lagoon at Doñana NP (Fig. 14) was
taken in from a light aircraft (a four-seat Cessna) in March 2014. Text Box 4 outlines the process and settings used to carry out an automatic count of the feeding
flamingos in Fig. 14.
The relatively plain background of standing water and the feeding spaces
between individual birds made this image equally suitable for an automatic or
manual count. This was reflected in the results from the two counts, with the autoImproving the Accuracy of Bird Counts Using Manual and Automated Counts…