ML516650671
gull sp. Larinae sp.
Contributor
Date
Location
- Age
- Not specified
- Sex
- Not specified
Observation details
Observations: 1) In the estuary Gulls are perching in large numbers in three layers (lines). 2) Only closest line to the beach can be viewed (with binocs/scope) & photographed 3) Two lines of gulls deep in the estuary cannot be counted but visibly the numbers are much more than the first visible line of the gulls 4) One additional flock of 400-500 individuals was perching at the river mouth Count: 1) In field - visually one large group was counted (base count) within the field of view of the binocs and the rest of the count was estimated against this group size. We estimated a definite count of over 10,000 individuals 2) From photographs - First line of the gulls (closest to the beach) are photographed (linearly from left to right) ensuring that images are not overlapping. This will ensure the best approximate count of birds from the photographs 3) Scale count - Using a scale (as shown in the collage) individuals within each unit on the scale was counted and multiplied with the total units. 4) Visual count - Birds in each photograph are directly counted by zooming in and total number is compared against the scale count 5) For the final number, minimum of the scale count and visual count was considered for each photograph. Ex: 170 individuals are estimated from an image in the collage by visual count whereas scale count is 180 individuals approximately. In this case, 170 individuals are considered for the count. 6) From all the set of images, about 3200 individual birds are estimated from the first line that was photographed 7) As we know that there are three lines of gulls, 3200X3 = 9600 individuals, adding the additional 400 birds perching at the river mouth, a total of minimum 10,000 individuals was approached. This is conservative count. Note: Not all images are added to the collage uploaded to this checklist. Collage is just to explain the count methodology.
Technical information
- Camera
- Microphone
- Accessories
- Original file size
- 141.79 MB