Measuring circulating triglycerides in free-living birds: evaluation of a field-usable point-of-care analyzer for American woodcock

Plasma metabolites such as triglyceride (TRIG) can be useful indicators of when birds are in a state of fattening or fasting, although the challenges of processing, storing, and analyzing field-collected plasma samples may limit its use by field ornithologists. We evaluated the use of a field-usable point-of-care (POC) analyzer (CardioChek PA analyzer) for measuring TRIG concentrations in the plasma of male American Woodcock ( Scolopax minor ) captured during their spring courtship period and compared those measures to those from standard laboratory analyses of the same plasma samples. Plasma TRIG measured in the field with the POC analyzer was highly repeatable and precise, but not accurate compared to lab-measured values. The inaccuracy of the POC analyzer may be due to the effects of environmental conditions on the analyzer’s function or to specific problems associated with analyzing woodcock blood. We conclude that the field-usable POC analyzer does not provide an accurate alternative method for measuring circulating TRIG in woodcock during cold springs in northern breeding areas. Given the analyzer has proven accurate for estimating circulating TRIG in some other bird species, we outline a two-phase pilot study that field ornithologists can use to understand the operating limits of this analyzer for their target species prior to field use.