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.     

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.     

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.     

Impact of spatial disjunction within biophysical classes on plant species composition: implications for conservation planning

The use of surrogates for biodiversity is a practical tool to improve the cost effectiveness of regional conservation planning. However, there is still much uncertainty about the biological representativeness of surrogates. Using a biophysical classification system known as the Mitchell Landscapes, we compare plant species composition in contiguous versus disjunct units of nine Landscape types and hence the ability of this surrogate to capture patterns of plant species composition. We found that plant species homogeneity was higher within a contiguous Landscape than between non‐contiguous units of the same Landscape. Overall, the dissimilarity between non‐contiguous units and their contiguous counterparts was significant (P = 0.004). Biophysical classes with very high dissimilarities between non‐contiguous units of the same region may be of limited utility.     

Effects of sandy beach cusps on wrack accumulation,sediment characteristics and macrofaunal assemblages

Beach‐cast marine macroalgae and seagrasses, collectively termed wrack, provide shelter and habitat for beach fauna and can often provide a large input of energy and nutrients to sandy beaches. Wrack deposition on sandy beaches varies spatially and could be affected by morphological features on the beach face such as cusps. This study tested a series of hypotheses regarding the differences in wrack deposits, sediments and macrofaunal assemblages between cusp bays and horns on two beaches in South Australia. Bays had greater cover and larger pieces of wrack than horns. Sediment organic matter content was greater on horns than in bays but mean particle size did not differ consistently between bays and horns. Macrofaunal diversity was higher in bays and this pattern was probably driven by differences in the cover of wrack between bays and horns. Cusp morphology thus influences the distribution of wrack on the beach face, which in turn influences the distribution of macrofauna. Studies of sandy beaches with cusps should therefore be explicitly designed to sample cusp features and associated wrack deposits.