Census & survey techniques

Question 1

Camera trap, line transect census and track surveys: a comparative evaluation
Camera trap > Track survey > Line survey

Answer 1

Silveira et al. 2003

Question 2

Sampling butterflies in tropical rainforest: an evaluation of a transect walk method
Transect walks more efficient than kite netting in accumulating individuals and species. However, difficulty distinguishing species within some tropical butterfly genera on the wing may prove a limiting factor.

Answer 2

Walpole & Sheldon 1999

Question 3

Nice review with plenty of examples of local collaboration

• Examples show that local people can be trained to be effective parataxonomists, greatly assisting efforts to document and assess tropical biodiversity.
• Tropical biologists need help as the workforce simply isn’t strong enough to document & investigate species before many of them go extinct.
• Local collaborations also offer promising ways with which to improve natural resource management and conservation.
• There are a number of reasons why collaboration doesn’t happen more, covered here

Answer 3

Sheil & Lawrence 2004

Question 4

Conventional surveys are demanding in terms of time, expertise and budget taken

• Survey methods employing local expertise can be much better: effective, reliable, low cost, faster way of clarifying presence & distribution of target species in any are with limited resources for conservation research
• In this survey only males over 20yrs were surveyed as they were the most familiar with the forest, but effort should be made not to leave out women, where they may have different knowledge sets

Answer 4

Padmadaba et al. 2013

Question 5

Census techniques for bird densities

• Surveying birds is hard because of diversity of species, cryptic behaviour, migration/nomadism and dense canopy habitat
• Fixed width line transects inflated the density, but easily applicable in monitoring programmes, Easy to analyse data & Useful for large-scale monitoring programmes
• Point Counts Useful in the censusing of cryptic, sedentary rainforest spp, Can carry out more point counts than line transect surveys at the same time
• Territory Mapping: was the best! Useful for territorial birds in small plots, Useful for when monitoring is targeted at a few spp., Too time and energy intensive for large-scale monitoring, Observers needed

Answer 5

Raman 2003

Question 6

• Care must be taken when interpreting density estimates from different areas obtained by different techniques.
• Challenges with primates: Live in the canopy – completely arboreal, 3D distribution, unpredictable when detecting humans

Range mapping: locate all groups and map their ranges
· Considered the most accurate approx. of true density BUT 3Ds of forest trees canopy make it difficult (trees up to 60m), Labour intensive, Ranges may overlap with other groups, Not suitable for mountainous rugged terrain where access possible only through ridges, Only applicable in small accessible areas

Count Transects: Fixed point counts: calling gibbons and counting how many calls heard
· Accurate density estimates can be made over relatively large areas
· Can be employed in unexplored terrain
· Can be employed in areas where other methods (CMR, territory mapping) are not feasible
· Allows for comparison between studies as easier to standardise
· Difficult to randomise as often have to follow landscape features (ridges, logging roads etc.)

Answer 6

Nijman & Menken 2005