A biological review of Pseudomys oralis: a response to Pyke and Read.

Abstract

IN their recent paper, Pyke and Read (2002) provide a detailed review of the biology and ecology of the Hastings River mouse Pseudomys oralis. The authors should be commended for compiling this information, however, there are some comments I would like to make to provide a contemporary review of this species. The authors note there has been no discussion of geographic variation within P. oralis or recognition of a subspecies. However, the recovery plan (NPWS 2003), which has been in draft for many years, emphasises the need to survey populations between the mitochondrial DNA haplotype sites identified by Jerry et al. 1998 to determine whether there are two distinct species. Pyke and Read (2002) also maintain the historical belief that P. oralis is mostly found in open habitat associated with riparian features (gullies and watercourses). Based on the studies of Townley (2000), Keating (2000) and new data collected by Meek (2002) and Meek et al. (2003), there is evidence that P. oralis is not dependent on riparian habitat. The species has been captured at many ridge and mid-slope sites where sedges and/or grasses are not found in high abundance. High numbers of P. oralis trapped and monitored at Marengo State Forest since 2000 have been found living on a ridge top in an open forest habitat dominated by fern (Meek 2002; Meek et al. 2003). Radio tracking and spool-and-line tracking from this forest showed that P. oralis did not favour a microhabitat of grasses or sedges and when riparian habitat was available the tagged animals rarely used it. Habitat at known P. oralis sites indicate that shelter is an important factor in population size, however emphasising the value of rock shelter as an indicator of capture success (Keating 2000) ignores the value of head and butt residue and fallen timber for the species. In all of the trapping sites described in Meek et al. (2003), none contained large amounts of large or small rock. However, occurrence of the species and trap success does correspond with the amount of hollows in fallen timber and residues from previous logging events and is further supported by tracking observations (Meek 2002, 2003).

Updating biological reviews: the Hastings River mouse Pseudomys oralis as a case history.

“…We also pointed out that existing approaches to understanding P. oralis habitat-use are based on presence/absence of the species and do not provide any measure of habitat suitability or preference (Pyke and Read 2003). On the other hand, a species clearly cannot be "dependent" on a habitat (i.e., populations unable to persist without it) in which it does not always occur, and, in this sense, we agree with Meek (2003) that P. oralis cannot be 'dependent' on riparian habitat. The relative suitability of riparian and other habitat types remains to be determined.…”

“…It has also been known that P. oralis may use a variety of alternative shelter sites, including rocks, tree hollows and fallen trees (Klippel 1992;MGP 1994;Smith et al 1995;SF NSW 1995a,b;Tanton 1995;Keating 2000;Townley 2000). Meek (2002;2003) provides additional similar examples, but these observations do not presently justify any modification to our summary statement. A quantitative analysis of macrohabitat across a range of P. oralis sites could, however, improve our understanding of habitat-use by this species.…”

“…The extent to which we were successful with these goals has been brought into question by Meek (2003) who suggests that we were inaccurate in some respects, omitted material in some relevant documents, and not as up-to-date as we could have been. Meek describes observations that are claimed to conflict with our conclusions in terms of habitatuse, population size and logging protocols.…”

“…At the time of our review only Townley (1997) had reported a population (Gambubal, Qld) of this species approaching 50 individuals. Now Meek (2002Meek ( , 2003 has reported another relatively 'large' population (Marengo State Forest, NSW), but with only 37 captures of 22 individuals after extensive trapping this population may not be very large either. Most known populations are apparently small but, since densities of P. oralis may be comparable to densities of other small mammals (Pyke and Read 2003), larger populations might occur where there are more extensive areas of suitable habitat.…”

“…We based our description on documentation available to us in about 2000 when we were completing our review (NSW NPWS 1999). These procedures apparently changed around this time (Meek 2003), although generally-available documentation concerning the new procedures did not appear until after we had submitted our manuscript. Further modifications are likely as new biological information becomes available and increasing cost-effective methods are pursued (Meek 2002).…”