50 Monitoring Threatened Species and Ecological Communities
four species most variable in numbers or distribution, two have no monitoring
(letter-winged kite Elanus scriptus, princess parrot Polytelis alexandrae) and two
(Australian painted snipe Rostratula australis, plains wanderer Pedionomus
torquatus) are subject to concerted monitoring effort. A surprising finding was that
monitoring probability increased with population size but declined with range
area. An explanation for this is that threatened birds with relatively large
populations are likely to be monitored through the ongoing Australian bird atlas,
because they are likely to be encountered by volunteer birdwatchers. Threatened
birds with small numbers occurring over large areas are more difficult to count
and include a suite of taxa such as northern masked owl Tyto novaehollandiae
kimberli and grey falcon Falco hypoleucos (both rarely seen but with huge
Fig. 4.4. Relationship between geography (a) and taxonomic group (b) and the quality of monitoring
undertaken on threatened or Near Threatened Australian bird taxa (bars represent 95% confidence intervals,
n = 157 ).