T.L. Moore

Do experimental methods affect estimates of pollen digestion by birds

Pollen protoplasts may supply important nutritional resources for birds; however, they are locked up within the mechanically strong and biochemically complex pollen wall. Previous studies of pollen digestion in birds have yielded highly variable and often contradictory results. We tested whether these differences could reflect the vastly different methodologies that have been used. We used a standard method to investigate digestion of Banksia grandis (Proteaceae) pollen in New Holland honeyeaters (Phylidonyris novaehollandiae). Four types of B. grandis pollen were examined: fresh, frozen for a week, stored in conditions to stimulate pregermination for 24h, or collected by honeybees. Our data indicate that although pollen treatment may influence digestibility of the pollen grains, these differences do not reach statistical significance because they are dwarfed by a high degree of variability between birds fed the same diet as well as variability in gut transit time (generally more pollen grains were digested over longer transit times). Similar patterns were observed for red wattlebirds (Anthochaera carunculata) fed bee-collected pollen. We believe that feeding behaviour or gut transit time may explain the marked differences between previous studies of pollen digestion by nectarivores, particularly the conflicting results for New Holland honeyeaters.

Does woodland condition influence the diversity and abundance of small mammal communities

Loss of mammal species in Australia in the last 200 years has been attributed to many factors including habitat removal and altered fire regimes. Decline in tree condition could contribute further to the ongoing decline of mammals. Eucalyptus wandoo trees are currently undergoing a decline in condition that can result in a loss of canopy and other changes to the habitat. This paper examines the relationships between E. wandoo tree condition, habitat characteristics and small mammal species richness and abundance. Live-capture trapping was conducted at 24 E. wandoo sites at Dryandra State Forest and Wandoo Conservation Park, Western Australia. Condition and microhabitat variables of E. wandoo were recorded for each site. Generalised additive mixed models revealed a range of habitat and tree condition characteristics that influenced small mammal abundance and species richness, including site litter cover, crown dieback, understorey vegetation cover and tree density. The availability of coarse woody debris played a large role in explaining the abundance of Cercartetus concinnus and Antechinus flavipes, along with other microhabitat and tree condition variables, such as tree leaf litter and crown dieback. Epicormic growth, crown density and the distance to the drift fence from E. wandoo trees were the common variables in the best model for the abundance of Sminthopsis griseoventer. The decline in condition of E. wandoo and the subsequent modifications to the microhabitat are correlated with changes in the small mammal community. A better understanding of how the decline of E. wandoo impacts small mammal communities could improve management practices in E. wandoo woodlands.

Is the reptile community affected by Eucalyptus wandoo tree condition

Abstract Context. Large portions of the world’s forests and woodlands are currently affected by declines in canopy condition of dominant tree species; however, the effects of these declines on faunal communities are largely unknown. Eucalyptus wandoo woodlands in the south-west region of Western Australia have demonstrated declines in condition since the early 1990s. Such declines in tree condition can result in reduced understorey vegetation, increased leaf-litter cover and coarse woody debris, potentially altering the habitat and resource available to reptiles. Prescribed fire events, another mechanism of habitat change for reptiles, are a common occurrence in these woodlands. Aims. The present research investigated whether reptile communities were influenced by E. wandoo tree condition, and the changes in the habitat associated with E. wandoo decline. Methods. Reptile trapping was conducted at 24 E. wandoo-dominated sites (of varying condition) in Dryandra State Forest and Wandoo Conservation Park, Western Australia. Overall, reptile abundance, species richness and individual reptile species abundances (only those species captured in sufficient numbers for analysis) were compared with a range of habitat characteristics that are likely to be altered by changes in E. wandoo tree condition. Key results. Overall, higher reptile abundance and species richness were observed at sites with longer time since fire and more site litter cover. There was also a greater abundance and diversity of reptiles at sites where E. wandoo trees exhibited fewer symptoms of tree decline. Similar analyses for the five most common skink species indicated species-specific relationships with tree-condition measures, time since last fire, site litter cover, distance to drift fence from E. wandoo trees, understorey vegetation density and the density of coarse woody debris. Conclusions. Abundance and species diversity of the reptile communities in E. wandoo woodlands were strongly related to time since last fire, E. wandoo tree condition and habitat characteristics such as site litter cover and the density of coarse woody debris. Implications. Decline in the condition of E. wandoo trees and the fire events in E. wandoo woodlands are both mechanisms of change correlated with reptile habitat and resources. Future management of E. wandoo woodlands may include reducing prescribed fire events in areas demonstrating symptoms of tree decline, to conserve reptile abundance and species richness.

Do woodland birds prefer to forage in healthy Eucalyptus wandoo trees

Abstract. Globally, many forests and woodlands are in decline. The marked loss of canopy foliage typical of these declines results in reduced foraging resources (e.g. nectar, pollen, and insects) and, subsequently, can reduce habitat quality for woodland birds. In south-west Western Australia, patches of Eucalyptus wandoo woodlands have shown a decline in condition since at least 2002. We investigated how changes in E. wandoo condition affect the woodland bird community. Foraging activities of three bird species were recorded for 20 sites in Dryandra State Forest and Wandoo Conservation Park either by conducting watches on focal trees (‘sitting’ method), or following individuals through the woodland (‘following’ method). Condition assessments of trees used by the birds were compared with those for trees available at the study site. Weebills (Smicrornis brevirostris; canopy insectivore) displayed preference for healthy trees (low amounts of canopy dieback), whereas rufous treecreepers (Climacteris rufa; bark-foraging insectivore) preferred trees with a higher proportion of dead branches. Yellow-plumed honeyeaters (Lichenostomus ornatus; insectivore/nectarivore) foraged in older, larger E. wandoo trees having full canopies with few signs of tree decline. Tree declines, such as that happening in E. wandoo, alter the foraging resources and habitat available to woodland birds.

Detecting, but not affecting, nest-box occupancy

Context. Nest boxes are a useful tool in the reintroduction, conservation and monitoring of many hollow-using species. Aims. All forms of nest-box monitoring involve some form of invasion, often upsetting their continued use by occupants. We conducted a pilot study to investigate and validate the innovative use of temperature dataloggers (iButtons®) to remotely monitor nest-box use, leaving the nest-box occupants untouched. Methods. In captivity, iButton recordings revealed the duration and time of day when each of the three nest-box designs was occupied by Pseudocheirus occidentalis (western ringtail possums); the accuracy of occupancy data was validated by unobtrusive infrared video recording. In the field, where translocated P. occidentalis and naturally occurring Trichosurus vulpecula (common brushtail possum) populations are present, hair sampling at the nest-box entrances (in addition to iButton recording) was used to identify the mammal species present. Key results. Nest-box use by captive P. occidentalis validated iButtons as a useful remote-monitoring tool, with 10 h) periods of continuous occupancy (T. vulpecula only). In addition to the convenience (to researcher and animal) of continuous (24-h) monitoring with minimal disturbance, a major advantage from using iButtons is that occupancy can be matched with environmental temperature or rainfall records, as well as other events (e.g. storms or frost). Conclusions. iButtons are a useful remote-monitoring tool of nest boxes, and it is possible that their use in this manner may be extended to tree-hollow occupation. Most importantly, this approach can inform us as to the conditions under which the nest boxes are used by fauna, as well as preferences for different nest-box designs. Implications. It is important to note that the criteria used for determining the presence or absence in the nest box (i.e. temperature difference, Tin– Tout, of 2°C) in the present study will not be relevant for all nest-box designs and before using these methods, the thermal properties of the nest box or tree hollow will require investigation.

Living (and reproducing) on the edge: reproductive phenology is impacted by rainfall and canopy decline in a Mediterranean eucalypt

Many of the worlds’ forests and woodlands are currently showing symptoms of declining condition due to a range of factors, including changing climatic conditions, drought and insect herbivory. Altered abiotic and biotic conditions can influence the condition of trees that can, in turn, affect tree reproductive cycles. However, the potential impact of tree decline on reproductive cycles has rarely been examined. This study investigated the influence of canopy condition on the reproductive cycle of Eucalyptus wandoo Blakely in south-western Australia. Canopy and seed trap monitoring were used to assess bud production, flowering, fruiting and seed fall over 12 months at 24 sites across two locations (Dryandra Woodland and Wandoo Conservation Park). Time since last fire, rainfall, ambient temperatures and the condition of individual trees were recorded. We found that bud production, flowering and fruiting was correlated with tree condition: healthier trees were generally associated with higher reproductive effort. Time since last fire was also strongly related to the reproductive efforts at both locations. Declining annual rainfall and increased temperatures also impact on reproduction, made evident by the aborted flowering in Dryandra Woodland. Decline in tree condition, coupled with changes in climate, have major implications for flowering phenology of this species and have the potential to alter reproductive effort, recruitment and future population dynamics. Consideration of these issues should be incorporated into the conservation management of E. wandoo and similar Eucalypt species.