ABSTRACT
- Accurate biodiversity and population monitoring is a requirement for
effective conservation decision-making. Survey method bias is
therefore a concern, particularly when programs face logistical and
cost limitations.
- We employed point count (PCs) and autonomous recording unit (ARUs) to
temperate mountain habitats (9 mountains in British Columbia (BC),
Canada and 10 in southern Chile). We compared detected species
richness against multi-year species inventories and examined
differences in detection probability by family. By incorporating time
costs, we assessed the performance and efficiency of single vs.
combined methods.
- ARUs were predicted to capture ~92% of species
present in BC but only ~58% in Chile, despite Chilean
mountain communities being less diverse. Community, rather than
landscape composition, appears to be the driver of this dramatic
difference. Chilean communities contain less-vocal species, which ARUs
missed6/14 families in BC were better detected by ARUs while 11/11
families in Chile were better detected by PCs. Where survey conditions
differentially impacted methods, PC detection varied over the morning
and with canopy cover in BC and ARU detection probability mostly
varied seasonally in Chile. Within a single year of monitoring,
neither method alone was predicted to capture the full avian
community, with the exception of ARUs in the alpine and subalpine of
BC. PCs contributed little to detected diversity in BC, but including
this method increases total time costs. Combining PCs with ARUs in
Chile significantly increased species detections, again, for little
cost.
- Combined methods were among the most efficient and accurate approaches
to capturing diversity. We recommend conducting observer point counts,
where possible, when ARUs are deployed and retrieved, in order to
capture additional diversity and flag methodology biases with.