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.