Salamander Dispersal Across a Forested Landscape Fragmented by a Golf Course

Abstract: We assessed dispersal behavior of 78 radiotagged adult spotted salamanders (Ambystoma maculatum) at a 36-hole golf course in southeastern Connecticut, USA. Lake of Isles Golf Course is atypical of most golf courses in North America because it is much larger (461 ha) than average 18-hole golf courses (54 ha) and deciduous forests accounted for 70% landscape composition on the course. We tracked individuals an average of 164 days as they emigrated from 3 seasonal pools surrounded by golf course fairways and one pool located in contiguous forest (control pool) from March through December 2004. Males and females dispersed similar distances at the control pool, averaging 71 ± 10 m. However, females migrating across the golf course dispersed twice as far (214 ± 25 m) as males on the golf course (102 ± 15 m) and both genders at the control pool. Over 40% the salamanders at the golf course crossed fairways; thus, fairways were not a dispersal barrier to adult spotted salamanders. Previous researchers have suggested establishing a 164-m life zone around breeding ponds to protect pond-breeding amphibian populations. Our results suggest that strategies that protect core upland habitat within 164 m of wetland boundaries would include 82% of adult males and only 50% of adult females. Empirical estimates based on our telemetry study suggest that core terrestrial habitat would have to extend 370 m to protect 95% of adult females, which is much farther than previous estimates.     

Responses of cetaceans to anthropogenic noise

• 1 Since the last thorough review of the effects of anthropogenic noise on cetaceans in 1995, a substantial number of research reports has been published and our ability to document response(s), or the lack thereof, has improved. While rigorous measurement of responses remains important, there is an increased need to interpret observed actions in the context of population‐level consequences and acceptable exposure levels. There has been little change in the sources of noise, with the notable addition of noise from wind farms and novel acoustic deterrent and harassment devices (ADDs/AHDs). Overall, the noise sources of primary concern are ships, seismic exploration, sonars of all types and some AHDs.
• 2 Responses to noise fall into three main categories: behavioural, acoustic and physiological. We reviewed reports of the first two exhaustively, reviewing all peer‐reviewed literature since 1995 with exceptions only for emerging subjects. Furthermore, we fully review only those studies for which received sound characteristics (amplitude and frequency) are reported, because interpreting what elicits responses or lack of responses is impossible without this exposure information. Behavioural responses include changes in surfacing, diving and heading patterns. Acoustic responses include changes in type or timing of vocalizations relative to the noise source. For physiological responses we address the issues of auditory threshold shifts and ‘stress’, albeit in a more limited capacity; a thorough review of physiological consequences is beyond the scope of this paper.
• 3 Overall, we found significant progress in the documentation of responses of cetaceans to various noise sources. However, we are concerned about the lack of investigation into the potential effects of prevalent noise sources such as commercial sonars, depth finders and fisheries acoustics gear. Furthermore, we were surprised at the number of experiments that failed to report any information about the sound exposure experienced by their experimental subjects. Conducting experiments with cetaceans is challenging and opportunities are limited, so use of the latter should be maximized and include rigorous measurements and or modelling of exposure.

     

Vertical stratification of feeding guilds and body size in beetle assemblages from an Australian tropical rainforest

Abstract The vertical stratification of insect species assemblages inhabiting tropical rainforests is well established but few have examined whether these patterns are reflected in vertical stratification of body size or feeding guilds. We used Malaise and Flight Interception Traps to sample beetle assemblages from five locations, at both canopy and ground zones of a tropical lowland rainforest site near Cape Tribulation, Australia. Beetles from 4 years of sampling were sorted to Family and morphospecies, and allocated to one of five feeding guilds. Within feeding guilds the number of species and individuals, from canopy‐ and ground‐caught traps were compared. The body lengths of species were measure and compared within feeding guilds and families. Herbivores was the dominant guild but was not the majority of all species or individuals. Most beetle species (69%) were less than 5 mm in length and the mean size of canopy‐caught species was greater than that for ground‐caught species. This was probably due to slightly more species of plant feeders (herbivores and xylophages) present in the canopy, which were significantly larger than saprophages, fungivores and predators. Among feeding guilds, there were few overall canopy–ground differences. These results contrast with species composition results presented elsewhere where strong differences between the canopy and the ground were evident. We suggest that our guild groupings may have been too coarse to detect fine‐scale differences and that resource partitioning may have also masked faunal stratification. We propose that fine‐scale differences in resources between the canopy and the ground, together with strong microclimate gradients, are likely to be important in structuring the vertical stratification of insect assemblages at the level of species, but not with respect to functional groups.     

Determinants of preferred intertidal feeding habitat for Eastern Curlew: A study at two spatial scales

Abstract Broadscale habitat use by Eastern Curlews (Numenius madagascariensis) in their non‐breeding range in eastern Australia was assessed using low tide surveys on feeding grounds, where 60 skilled volunteers made repeated counts of the birds on intertidal flats, across 41% (9500 ha) of the intertidal habitat within Moreton Bay, Australia. We analysed 32 defined sections of intertidal flat, of roughly equal area (mostly 200–400 ha), which varied greatly in their curlew density (2–47 birds per 100 ha) and also in substrate and other environmental features. Sites with the least resistant substrates had densities three times those with the most resistant substrates. Of 10 environmental characteristics measured for each site, substrate resistance was the best predictor of curlew density (r² = 0.45). Characteristics that were poor predictors included distance to the nearest roost, level of human disturbance and distance to urban settlement. For a finer‐scale assessment, microhabitat use and feeding behaviour were recorded during low tide within 12 intertidal flats, which varied in size (23–97 ha), substrate, topography and other features. Across all flats, curlews strongly preferred to feed relatively close (0–50 m) to the low‐water line. They fed on a variety of substrates (including sand, sandy‐mud, mud and seagrass) in broadly similar proportions to their occurrence in the habitat. There was a statistically significant preference for sand, although its magnitude was not strong. These results indicate that curlews select habitat most strongly at a between‐flat rather than within‐flat scale.     

Do Australian small mammals respond to native and introduced predator odours?

Abstract Coevolution is thought to have led to many small mammal species avoiding the scent marks of their main mammalian predators, as they provide a reliable cue to predation risk. Most support for this hypothesis comes from northern hemisphere predator/prey systems, however, it is unclear whether this avoidance of predator faecal odour occurs in Australia's mammalian fauna, which has evolved in relative isolation from the rest of the world, and is dominated by marsupials rather than placentals. We tested this theory for an Australian system with marsupial and placental predators and prey, that share a long‐term (>1 million years) or short‐term (<150 years) exposure to each other. The predators were the native marsupial tiger quoll Dasyurus maculatus and the introduced placental red fox Vulpes vulpes. The potential prey were three native rodent species, the bush rat Rattus fuscipes, the swamp rat Rattus lutreolus, the eastern chestnut mouse Pseudomys gracilicaudatus, and the marsupial brown antechinus Antechinus stuartii. Small mammals were captured in Elliott traps with 1/3 of traps treated with fox faeces, 1/3 treated with quoll faeces and the remainder left untreated. The native rodent species all showed avoidance of both tiger quoll and red fox odours whereas the marsupial antechinus showed no responses to either odour. Either predator odour avoidance has not evolved in this marsupial or their reaction to predator odours may be exhibited in ways which are not recognizable through trapping. The avoidance by the rodents of fox odour as well as quoll odour indicates this response may either be due to common components in fox and quoll odour, or it may be a recently evolved response.     

Ten years of invasion: Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) in Britain

1. Harmonia axyridis was first recorded in Britain in 2004. Two subsequent earlier records were received from 2003. 2. The UK Ladybird Survey, a citizen science initiative involving online recording, was launched in 2005 to encourage people across Britain to track the spread of H. axyridis. Tens of thousands of people have provided records of H. axyridis and other species of ladybirds, creating an invaluable dataset for large‐scale and long‐term research. Declines in the distribution of seven (of eight assessed) native species of ladybird have been demonstrated, and correlated with the arrival of H. axyridis, using the records collated through the UK Ladybird Survey. 3. Experimental research and field surveys have also contributed to our understanding of the ecology of H. axyridis and particularly the process of invasion. Harmonia axyridis arrived in Britain through dispersal and introduction events from regions in which it was deliberately released as a biological control agent. The rapid spread of this species has been attributed to its high natural dispersal capability by means of both flight and anthropogenic transport. A number of factors have contributed to the successful establishment and indeed dominance of this polymorphic species within aphidophagous guilds, including high reproductive capacity, intra‐guild predation, eurytopic nature, high resistance to natural enemies within the invaded range, and potentially phenotypic plasticity. 4. The global invasion by H. axyridis and subsequent research on this species has contributed to the general understanding of biological invasions.     

Semiempirical modeling of abiotic and biotic factors controlling ecosystem respiration across eddy covariance sites

In this study we examined ecosystem respiration (R_ECO) data from 104 sites belonging to FLUXNET, the global network of eddy covariance flux measurements. The goal was to identify the main factors involved in the variability of R_ECO: temporally and between sites as affected by climate, vegetation structure and plant functional type (PFT) (evergreen needleleaf, grasslands, etc.). We demonstrated that a model using only climate drivers as predictors of R_ECO failed to describe part of the temporal variability in the data and that the dependency on gross primary production (GPP) needed to be included as an additional driver of R_ECO. The maximum seasonal leaf area index (LAI_MAX) had an additional effect that explained the spatial variability of reference respiration (the respiration at reference temperature T_ref=15 °C, without stimulation introduced by photosynthetic activity and without water limitations), with a statistically significant linear relationship (r²=0.52, P<0.001, n=104) even within each PFT. Besides LAI_MAX, we found that reference respiration may be explained partially by total soil carbon content (SoilC). For undisturbed temperate and boreal forests a negative control of total nitrogen deposition (N_depo) on reference respiration was also identified. We developed a new semiempirical model incorporating abiotic factors (climate), recent productivity (daily GPP), general site productivity and canopy structure (LAI_MAX) which performed well in predicting the spatio‐temporal variability of R_ECO, explaining >70% of the variance for most vegetation types. Exceptions include tropical and Mediterranean broadleaf forests and deciduous broadleaf forests. Part of the variability in respiration that could not be described by our model may be attributed to a series of factors, including phenology in deciduous broadleaf forests and management practices in grasslands and croplands.