Population Estimates and Echolocation Calls of Edible-nest Swiftlets (Collocalla fuciphaga) in Pilar Caves

Abstract

Swiftlets is of special interest due to its use of echolocation and its intricately constructed saliva nests which in some species contain no other material such as feathers, moss or twigs and are collected, selling at extremely high prices. This study was conducted to assess the population estimates and echolocation calls of edible -nest swiftlets (Collocalla fuciphaga) in Pilar Caves. This study was conducted at Balisong Cave in the Municipality of Pilar during the Month of September – October 2019 using descriptive survey method. A mark-recaptured method was done in determining the population size. A 35-mm monofilament mist nets of 12 m length x 2 m wide, 9 m length x 2 m wide and 6 m length x 2 m wide was used to catch swiftlets. Proper identification were done through published books, journals and INatural.Org. Echo-Sonar meter and frequency generator was used to measure and observed the echolocation calls of swiftlets. The sounds were recorded as they enter the cave and find their way to their nest in a dark environment. A 273 population estimates of cave swiftlets were recorded from Site A, 157 were recorded on Site B and 172 were recorded from Site C with a total population estimates of 602 cave swiftlets. Clumped dispersion in all sample sites were also observed. A succession of single click (6.97 Hz) followed by pause and a succession of double click (8.81 Hz) followed by a pause and a succession of single click (8.50Hz) was observe. As it enters the dark environment it produces a very high frequency 125.2 Hz and echo level of 0.50%. A high frequency of sound increase as it enters the dark environment was observed.