2.3 Data analysis:
2.3.1 Quantity and
quality of tracking data
A total of 162 peer-reviewed studies were included in this review, from
which 107 were used to assess data quality and quantity. Twenty-two
studies were omitted because they tracked taxa with insufficient sample
sizes for analysis (reptile = six studies & fish = two studies) or
seed/ fruit resources (14 studies). Resource tracking studies were
omitted from this part of the analysis as this method of tracking is
limited by study design and results were not comparable to the use of
GPS and radio transmitters. A further 33 studies were omitted as the
publications failed to report the required information, i.e., individual
tag performance and information was not recorded or available.
To calculate the mean number of tag days, 84 studies representing 130
individual species were used. To calculate mean tag locations, 81
studies representing 117 individual species were used. Generalised
linear models (GLMs), with a log-link function, were fitted to assess
the effect of taxa (bird or mammal) or tracking method (GPS or radio
tracking) on the number of tagging days and number of tagging locations
recorded. Models with and without interaction terms were compared using
Akaike Information Criterion (AIC) values, and the model with the lowest
AIC was selected.