A snake in paradise: Disturbance of plant reproduction following extirpation of bird flower-visitors on Guam

The introduction of an alien top predator, the brown treesnake (Boiga irregularis), has resulted in severe losses of native vertebrate populations in Guam. Among these are important pollinators and seed dispersers. This study is a first attempt to document cascading effects on vertebrate-pollinated native plant species in Guam. We investigated flower visitation, seed set and germination in two native plants, the mangrove tree Bruguiera gymnorrhiza and the forest tree Erythrina variegata var. orientalis. Both species are bird-pollinated. Studies were conducted on two Mariana islands, Guam (with high density of snakes) and Saipan (with nearly no snakes). Visitation rates by birds were high on Saipan, but zero on Guam. Insects and lizards visited flowers to a low extent on both islands. Only lizards were potential effective pollinators. Seed set of both species were significantly higher on Saipan compared to Guam, and for B. gymnorrhiza, seedling recruitment was significantly higher on Saipan. Hence, these bird-pollinated species appear highly dependent on bird visitors for reproduction. The eradication of flower-visiting birds by the invasive treesnake thus secondarily results in broken mutualistic interactions, which may, in turn, result in a lower recruitment of native plants. Thus, the treesnake affects not only potential prey species, but its effects cascade through the entire ecosystem on Guam. Conservation actions should be directed towards an improved recruitment (artificial pollination, planting) of the affected plant species.     

Determination of whole-body rotenone residues in the brown tree snake (Boiga irregularis)

The brown tree snake (Boiga irregularis) is an introduced pest in Guam, responsible for extensive agricultural damage, the extinction of several bird species, and severe and frequent electrical power outages. Rotenone, a naturally occurring pesticide, has been investigated as a possible chemical control agent. An analytical method was developed to assess whole body rotenone residues ranging in concentration from 0.035 to 250 microg g(-)(1) in snakes. The method employed ethyl acetate extraction of 2 g samples of cryogenically frozen, pulverized snakes, followed by silica and Florisil solid-phase extraction cleanup. Extract analysis was performed using a high-performance liquid chromatography system employing a cyanopropyl analytical column. Tissues fortified to concentrations of 0.035, 4.82, and 250 microg g(-)(1) yielded analyte recoveries of 85.1, 85.6, and 83.5%, respectively. The linear response of rotenone standard solutions was assessed from 0. 025 to 0.25 microg mL(-)(1) (r(2) = 0.9968) and from 0.250 to 125 microg mL(-)(1) (r(2) = 0.9999). The method was simple, rugged, and reliable.     

Life history attributes of the threatened Australian snake (Stephen's banded snake Hoplocephalus stephensii, Elapidae)

Whether or not a species is threatened by habitat change is influenced by its life-history traits as well as by the nature and severity of the threatening process. Detailed studies of declining taxa can clarify reasons for their vulnerability, both in proximate terms (e.g., taxa with slow growth, delayed maturation, low fecundity and infrequent reproduction will be poorly suited to withstand increases in adult mortality rates) and in an evolutionary perspective (i.e., what attributes of the environment have favoured the evolution of certain life history traits?). We obtained data on life history traits during an intensive radio-tracking study on the threatened arboreal elapid snake Hoplocephalus stephensii from forest habitats of eastern Australia. Based on 39 field-collected specimens, these long, slender snakes (mean adult snout-vent length 73 cm, mass 114 g) feed predominantly on mammalian prey such as Bush Rats (Rattus fuscipes) and Pygmy-possums (Cercartetus nanus); but juveniles also take lizards. Foraging modes are diverse, from active searching through to ambush. Gape-limitation prevents snakes from ingesting adults of the most abundant local rodent (R. fuscipes), limiting the snakes to specialise on sub-adult rats which are only seasonally available. Rates of feeding, growth and reproduction are low; for example, none of 21 wild-caught females was reproductive. However, snakes given access to abundant prey in captivity, rapidly gained in body condition, grew significantly, and subsequently reproduced. Litters consisted of a few (1-9), relatively large (25 cm snout-vent length, 7.5 g) offspring. The “slow” life-history traits that have contributed to endangerment of this taxon may include proximate as well as evolutionary responses to the low temperatures and limited prey availability in the forest habitat of H. stephensii.     

Snake species distributions and temperate grasslands: A case study from the American tallgrass prairie

Many snake species are declining globally, yet data unavailability in temperate grasslands hinders snake conservation in one of the world’s most endangered biomes. To encourage and inform the conservation of snakes in these regions, I examined snake species diversity and abundance during 2 years of a mark-recapture study at 22 sites located in six American tallgrass prairie preserves in northern Illinois, USA. I emphasized landscape-scale relationships after accounting for covariance with environmental factors at both finer (microhabitat) and broader (regional) scales. A total of 120 snakes representing seven species was captured using drift fence arrays associated with funnel traps and sheet metal cover. The low numbers and diversity of snakes captured, when compared to historic evidence, indicate that since the 1930s Midwestern snake populations have declined. Non-metric multidimensional scaling and Mantel tests demonstrate that differences in snake species composition in remnant and degraded prairies are discernable along gradients of urban and agricultural land cover. However, different patterns of abundance for individual snake species indicate that the relative importance of specific landscape factors differ among species, which has significant conservation implications. Here, I recommend that conservationists use a species-specific approach to manage snake populations. I also stress the need for thorough inventory of snake populations and studies of snake-habitat relationships to advance our understanding of snake ecology and conservation within the little studied temperate grassland habitats of South America and eastern Eurasia.     

Temporal genetic analysis of the critically endangered oriental white-backed vulture in Pakistan

Populations of oriental white-backed vultures (Gyps bengalensis) in south Asia have declined over 95% since the mid-1990s due to feeding on livestock carcasses that had been treated with diclofenac, an anti-inflammatory pharmaceutical that is fatal to Gyps vultures. To prevent extinction, captive breeding efforts have been initiated; however, given the overall decline, it is not known to what extent levels of genetic diversity currently exist in the remaining populations. Here we document temporal genetic diversity levels during the 2000-2006 interval for the last remaining breeding colony of oriental white-backed vultures in Pakistan, and show with simulations that a much larger captive population size is required than currently maintained to prevent further loss of genetic diversity. Before this species is extinct in the wild, it is crucial that additional individuals are included in the captive population.     

The invasion of two native Eucalypt forests by Pinus radiata in the Blue Mountains, New South Wales, Australia

Invasions of Pinus species are a major environmental concern in South Africa and New Zealand where pines are beginning to dominate native grasslands and shrublands. Pines are widely cultivated in Australia with almost a million hectares growing in large plantations. Plantations are commonly bordered by native Eucalypt vegetation resulting in a high potential for invasion and providing an opportunity to study pine invasion processes within forest environments.In order to determine if Pinus radiata equally invades different dry Eucalypt woodland vegetation types, two areas in the upper Blue Mountains in New South Wales, Australia were surveyed. Similar levels of invasion were observed in both Eucalypt forest types. An average pine abundance of 55 individuals for the Eucalyptus oreades and Eucalyptus sieberi vegetation type and 49 individuals for the Eucalyptus mannifera and Eucalyptus dives vegetation type was recorded in 20 m by 20 m plots located 50 m from the plantation boundary. To characterise the spatial distribution of the pines, transects were placed perpendicular to the plantation edge. As expected pine numbers diminished with distance from the plantation, however, large reproductive pine trees were found up to 4 km from the seed source signifying long distance dispersal.Investigation of wildling pine response to fire suggests that it may not always be an appropriate management tool. Fire stimulated seed release from cones and resulted in high recruitment of seedlings around reproductive pines which were large enough to survive the burn. Infrequent fires at intervals greater than time to maturity will lead to increased pine densities and further spread into the native vegetation.     

Survival rates of sea snakes caught by demersal trawlers in northern and eastern Australia

This paper examines the survival rates of sea snakes caught in research and commercial trawls in the main fishing grounds of northern and eastern Australia. Observers recorded whether the snake was alive or dead when it was landed on deck, and (if possible) its species, its length and weight, the duration of the trawl and the total weight of the catch. To estimate long-term survival, captured sea snakes were kept in sea water in drums on a large research vessel and monitored after 1, 6, 12, and 24 h then daily for up to 4 days. Up to 28% of all sea snakes landed on deck from commercial prawn trawling were found to be dead. Both duration of the trawl and catch weight had significant (P<0.001) positive effects on within-trawl (short-term) mortality of these sea snakes. About 30% of all sea snakes from 30 min duration trawls died during the 4-day survival experiment, with Hydrophis ornatus showing the highest mortality (< 50% alive after 96 h in a tank). Hydrophis elegans appeared to have the lowest mortality rate after capture (94% alive after 96 h). Overall, mortality from research and commercial prawn trawling was estimated as 48.5% of snakes caught. Visible damage to sea snakes by trawling was relatively low (5.4%). The introduction of Bycatch reduction devices, such as square mesh and fisheye windows, should improve the survival of sea snakes by reducing the catch weight and the number of sea snakes being caught.     

Low genetic diversity threatens imminent extinction for the Hungarian meadow viper (Vipera ursinii rakosiensis)

Meadow vipers (Vipera ursinii) are small venomous snakes whose range in Hungary has been greatly fragmented by anthropogenic habitat disturbance (especially, agriculture). We obtained DNA from a total of eight Hungarian snakes. Genetic variability at the major histocompatibility (Mhc) class I loci was much lower for these snakes than for specimens from two large Ukrainian populations. Within two Hungarian populations for which we had multiple individuals, band-sharing indices were 100 and 84.6% (versus 63.3 and 57% for the Ukraine populations). The Ukrainian snakes also displayed more RFLP fragments than the Hungarian vipers (mean 13.7 versus 9.0, respectively). In combination with reports of birth deformities, chromosomal abnormalities and low juvenile survival, these data strongly suggest that the Hungarian vipers are experiencing inbreeding depression. Genetic diversity is still present in the Hungarian vipers but among rather than within populations. Given the very low numbers of animals, the only feasible strategy to increase the genetic diversity and to save the Hungarian vipers from extinction is to implement a captive breeding program based on genetically screened animals.     

Snake prices and crocodile appetites: Aquatic wildlife supply and demand on Tonle Sap Lake, Cambodia

Commercial trade is a major driver of over-exploitation of wild species, but the pattern of demand and how it responds to changes in supply is poorly understood. Here we explore the markets for snakes from Tonle Sap Lake in Cambodia to evaluate future exploitation scenarios, identify entry points for conservation and, more generally, to illustrate the value of multi-scale analysis of markets to traded wildlife conservation. In Cambodia, the largest driver of snake exploitation is the domestic trade in snakes as crocodile food. We estimate that farmed crocodiles consume between 2.7 and 12.2 million snakes per year. The market price for crocodiles has been in decline since 2003, which, combined with rising prices for their food, has led to a reduced frequency of feeding and closure of small farms. The large farms that generate a disproportionate amount of the demand for snakes continue to operate in anticipation of future market opportunities, and preferences for snakes could help maintain demand if market prices for crocodiles rise to pre 2003 levels. In the absence of a sustained demand from crocodile farms, it is also possible that alternative markets will develop, such as one for human snack food. The demand for snakes, however, also depends on the availability of substitute resources, principally fish. The substitutability and low price elasticity of demand offers a relatively sustainable form of consumerism. Given the nature of these market drivers, addressing consumer preferences and limiting the protection of snakes to their breeding season are likely to be the most effective tools for conservation. This study highlights the importance of understanding the structure of markets and the behaviour of consumer demand prior to implementing regulations on wildlife hunting and trade.     

Do frugivorous birds assist rainforest succession in weed dominated oldfield regrowth of subtropical Australia?

Exotic plants often form the first woody vegetation that grows on abandoned farmland. If this vegetation attracts vertebrate frugivores which disperse the seeds of native plants, then native plants may recruit to such oldfield sites. However, there is debate about the extent to which exotic vegetation assists or suppresses the regeneration of native plants, and about its effects on faunal biodiversity. These issues were investigated in subtropical eastern Australia, where rainforests were cleared for agriculture in the 19th century, and where regrowth dominated by camphor laurel (Cinnamomum camphora, an exotic, fleshy-fruited tree) has become common on former agricultural land. The study assessed the assemblages of frugivorous birds, and the recruitment of rainforest plants, at 24 patches of camphor laurel regrowth. The patches were used by nearly all frugivorous birds associated with subtropical rainforest. Many of these birds (16 of 34 species) are considered to have a medium to high potential to disperse the seeds of rainforest plants, and eight of these were abundant and widespread in regrowth patches. Of 208 recorded plant species, 181 were native to local rainforest. The ratio of native to exotic species was higher amongst tree recruits than adult trees, both for numbers of species and individuals. Among native tree recruits, 79% of 75 species, and 93% of 1928 individuals, were potentially dispersed by birds. These recruits included many late-successional species, and there were relatively more individuals of late-successional, bird-dispersed native species amongst recruits than adult trees. The species richness, but not the abundance, of both frugivorous birds and of bird-dispersed rainforest trees decreased with distance from major rainforest remnants. Camphor laurel regrowth provides habitat for rainforest birds and creates conditions suitable for the regeneration of native rainforest plants on abandoned farmland. Careful management of regrowth dominated by fleshy-fruited exotic invasive trees can provide an opportunity for broadscale reforestation in extensively-cleared landscapes.     

Hybridization mechanisms between the endangered marble trout (Salmo marmoratus) and the brown trout (Salmo trutta) as revealed by in-stream experiments

Populations of the marble trout (Salmo marmoratus) are critically declining due to introgression by brown trout (S. trutta) strains. Hybrids between the two forms are fertile and presently predominant in most rivers of the species’ range.The involved hybridization mechanisms have been studied through two large scale in-stream experiments (Driselpoh and Stopnikarca) as 50% of each species have been stocked at the age of one year in fishless streams, each fish being individually marked. Diagnostic molecular markers were applied to test a partial reproductive isolation between the two species. Emphasis was put on survival and growth patterns of stocked fish (parental generation) as well as on fish hatched within the stream (F₁ generation).No evidence of a partial reproductive barrier between the two species was observed. Survival of the parental generation depended on the year in both streams, as well as on the species in Stopnikarca, but was identical for both species in Driselpoh. In both streams survival of instream hatched individuals measured from 0+ to 2+ was lower for brown trout. In Driselpoh, F₁ 0+, 1+ and 2+ hybrids were larger than pure individuals. Larger hybrids were only observed in Stopnikarca when analyses focused on individuals in inter-specific competition suggesting that heterosis and stress effects may explain the observed size differences.Our results point out important ecological differences between marble and brown trout and have shown that hybridization can easily take place. The findings indicate that high F₁ hybrid presence, survival and heterosis effects may impede marble trout rehabilitation in the area.     

Exposure to ecotourism reduces survival and affects stress response in hoatzin chicks (Opisthocomus hoazin)

Ecotourism helps to protect many habitats, but may also have negative impacts on wildlife. We investigated effects of ecotourists on reproductive success of hoatzins (Opisthocomus hoazin) and on hormonal status of their chicks in Amazonian rainforest lakes by comparing birds from undisturbed and from tourist-exposed nests. Hatching success was similar in both groups but chick survival was much lower at tourist-exposed nests than at undisturbed nests. This effect was due to an increased mortality of juveniles prior to fledging whereas small nestlings seemed largely unaffected. Juveniles, but not nestlings, living at tourist-exposed sites had a lower body mass and showed a stronger hormonal response to experimental stress compared to individuals at undisturbed sites. These data suggest that juvenile hoatzins were susceptible to tourist-induced stress which in turn may be responsible for the lower survival. In contrast, adult hoatzins that were incubating had apparently habituated to tourist presence because their flush distances at tourist-exposed nests were 50% lower than at undisturbed sites. Our findings demonstrate that individuals in different life stages show different susceptibilities to tourism. We suggest that even just watching animals during breeding can threaten their survival, but a proper scientific management of off-limit zones and area-specific guidelines for wildlife observation could reduce harmful effects.     

Biology and status of timber rattlesnake (Crotalus horridus) populations in Pennsylvania

The purpose of this study was to examine certain aspects of the life history and ecology of the timber rattlesnake (Crotalus h. horridus) in Pennsylvania, and to evaluate the reported decline in numbers of this species. The influence of commercial hunting has been considered and suggestions are made for conservation of this unpopular but intriguing snake.The previous and present abundance of rattlesnakes was first considered by a programme of interviews with commercial hunters. Visits were also made to many supposed den sites in central Pennsylvania, and to four rattlesnake hunts held in the summer of 1976. There were consistent reports of a large recent decline in the number of rattlesnakes seen and captured. These opinions of the scarcity of rattlesnakes were personally confirmed by visits to known dens. One rattlesnake den was chosen for a study on dates of first capture in the spring, on transplantation of snakes from other localities, on movements of newly released and long-term den residents, and on rodent populations. During three consecutive springs the dates of first capture of rattlesnakes varied only between April 23 and 30, despite marked differences in the pattern of air and ground temperature variation. Many snakes transplanted to a new den site apparently left the area almost immediately. Six out of 33 adults released were recaptured at the new den; three of these hibernated there. Only one of the 48 newborn rattlesnakes released soon after birth in the autumn was recaptured in the subsequent spring. On emergence from hibernation two rattlesnakes were tracked by radiotelemetry. They remained at the den until June, and left soon after shedding. One snake was followed to a distance 1055 m from the den over a period of 69 days. Considerable rodent food was available on the talus slopes of this den. Mice (Peromyscuc leucopus) were abundant; in a 0·7 ha grid trapped for one week the population was estimated at 61/ha. Nine gravid rattlesnakes were held in the laboratory to obtain information on litter size. The average litter was seven (range 5–9) and females lost an average of 41% of their body weight during parturition. The metabolic demands of pregnancy are high and females only reproduce every two, or possibly every three, years. The smallest female to produce a litter had a snout-vent length of 770 mm, and it is estimated that this animal was five years old. Positive correlations between head length and snout-vent length, and body weight and snoutvent length were found. No significant differences in these relationships between the sexes or between snakes freshly caught in different areas were noted. There was a decline in relative body weight and head length after prolonged starvation in captivity. Male rattlesnakes have significantly longer tails than females. The timber rattlesnake in Pennsylvania is rapidly approaching extinction. Prohibition of bounties, snake hunts, and commercial sale of snakes, and protection of rattlesnakes in remote areas of state and national forests would significantly enhance the prospects for survival of viable populations of Crotalus horridus.     

Pragmatic management increases a flagship species, the Himalayan brown bears, in Pakistan’s Deosai National Park

Deosai Plateau in Northern Pakistan was designated a national park to protect the largest remnant population of brown bears in Pakistan. The natural resources of this high elevation (3500-5000 m) park make a significant contribution to the livelihood of local and nomad communities. The present legislation excludes people from a park, which increases conflicts between management and local people. However, a pragmatic approach was adopted to involve people in conservation in Deosai. Community participation, achieved by recognizing rights and introducing incentives, reduced resistance against the conservation efforts, reduced grazing pressure in bear habitat and helped reduce poaching. The size of the brown bear population was set as an indicator of park success, and was monitored annually from 1993 through 2006. We observed a 5% annual growth of the brown bear population, suggesting that the conservation program has been successful due to a successful cooperation between an NGO, people, and the park management.The increase of the bear population is significant, because we observed an extremely low reproductive rate, due to late age of first reproduction (8.25 years), a long reproductive interval (5.7 years), and a small litter size (1.33). The reproductive rate of the Deosai population is the lowest yet documented for brown bear populations. Poor habitat quality, low quality food, high seasonality, and extreme weather conditions in the Himalaya probably explain the poor reproductive performance. Considering such low reproduction and known exchange of individuals with neighboring populations, we believe that the observed growth was a sum of reproduction and immigration. Brown bears are declining throughout South Asia and often have low-productive rates. Therefore, conservation efforts for brown bears in this region must target reducing human-caused mortalities, particularly of adult females. Involvement of people can increase efficiency in conservation, in addition to reducing cost and conflicts.     

Beyond the wetland border: Estimating the impact of roads for two species of water snakes

We used models integrating road maps, traffic volume, and snake movements to examine the potential for roads to contribute to mortality in two species of water snakes that differ in their vagility, use of terrestrial habitats, and conservation status. Road networks and traffic volumes typical of three regions in Indiana, USA, may account for mortality of 14-21% of the population per year in the more vagile, terrestrial, and imperiled copperbelly water snake (Nerodia erythrogaster neglecta) but only 3-5% mortality in the more sedentary, aquatic, and common northern water snake (Nerodia sipedon). The majority (>91%) of road crossings and associated mortality are predicted to occur during overland migrations to other wetlands, suggesting roads bisecting travel routes between wetlands may function as mortality sinks. Our models highlight the proportionately greater risk of mortality for the more vagile and imperiled species, N. e. neglecta, and suggest current wetland conservation strategies that focus on the wetland alone are unlikely to adequately protect wetland biodiversity from certain types of anthropogenic habitat modification. What is needed is a landscape approach to wetland conservation that considers not only the quality of wetlands and nearby terrestrial habitats, but also ensures that terrestrial corridors between wetlands remain permeable and offer safe passage for wildlife.     

Life cycle and reproductive traits of the earthworm Aporrectodea trapezoides (Dugès, 1828) in laboratory cultures

The parthenogenetic earthworm Aporrectodea trapezoides (Dugès, 1828) is widely distributed all over the world due to European agricultural practices. In order to provide baseline life cycle data, cocoons were obtained from field-collected individuals and their features and viability, incubation period, number of hatchlings and mortality rate were recorded. Singleton and twin earthworms from this first experiment were cultured from hatching during a 490-day period under controlled conditions with biomass, survival, reproductive condition and cocoon production recorded at intervals of 15 days. On average, individuals of isolated-reared A. trapezoides reached maturity at day 153 and body weight at maturity was approximately 1 g. In order to record reproductive traits and differences between field-collected and laboratory-reared individuals, 40 microcosms with an isolated earthworm (20 with field-collected individuals and 20 with laboratory-reared ones) and 40 containing groups of three (20 with each type of individual) were maintained during a complete year under controlled conditions. The amount of soil per individual was the same in both types of microcosm. Both the individuals kept in isolation and those cultured in groups produced cocoons, hence completely proving the obligatory parthenogenetic reproduction in this species without copulation or need of any physical-chemical stimulus. In general, isolated earthworms produced a significantly higher number of cocoons than those in groups of three, and the same was recorded for laboratory-reared earthworms when compared with field-collected ones. This study highlights the importance of knowing the life cycle and reproductive traits of one possible key species in soil management due to its vast distribution and high density in soils, and the species’ highly recommended use in applied studies because of its ease of culture.     

Genetic consequences of intensive management in game birds

Introduction of wildlife for game restocking is one major pathway of genetic homogenization. The red-legged partridge (Alectoris rufa, Phasianidae), a small game bird native to south-western Europe, is in high demand by hunters and natural populations are constantly supplemented by commercial stocks of captive-bred individuals. Also, in recent years human-mediated hybridization with congeneric chukar partridges (Alectoris chukar: Greece, Cyprus, from Middle East to East Asia) has been frequently documented in the wild and in captivity. This study attempts to evaluate the genetic consequences of intensive captive breeding and restocking in the A. rufa species. We investigated A. rufa genetic diversity by making comparisons in both a spatial (across the entire species’ range) and a temporal framework. We accomplished this latter by comparing modern vs. ancient partridges resident in museums and collected 1856-1934, well before supplemental stocking became common. Using mtDNA we found significant changes in the haplotype profile of modern vs. ancient A. rufa, and widespread introgression with chukar genes across the entire species range only in modern representatives, with the relevant exception of Corsican populations. However, Random Amplified Polymorphic DNA (RAPD), as opposed to microsatellite DNA markers, showed also modern Corsican populations to harbour many A. rufa × A. chukar hybrids. We conclude that captive breeding programs should make strict use of time-saving and comparatively low cost DNA barcodes to minimize genetic pollution, such as those provided by diagnostic RAPD markers. We also recommend that the active ban on import of exotics and/or hybrids be extended to non-local populations. Altogether this would represent a substantial step forward to preserve A. rufa as well as other game species subjected to similar intensive management.     

Changes in a remnant of salmon gum Eucalyptus salmonophloia and York gum E. loxophleba woodland, 1978 to 1997. Implications for woodland conservation in the wheat-sheep regions of Australia

The condition of salmon gums Eucalyptus salmonophloia with large hollows in them in a 15-ha patch of remnant salmon gum-York gum E. loxophleba woodland in the northern wheatbelt of Western Australia was examined in 1978. The patch was an important breeding area for six species of cockatoo, including two endangered species. The patch was revisited in 1981 when the condition of all 682 salmon gums and York gums in the patch was examined and each was measured and photographed. A further visit was made in 1997 when the condition of the surviving trees was examined and each was again measured and photographed. The condition of the trees at each visit was classified as “good”, “staghorn”, “broken top”, “dead” or “fallen.” Over the period of the study there was a serious decline in the condition of the trees, with few large trees in the “good” category by 1997. The decline was particularly marked between 1978 and 1981 after a period of well-below average annual rainfall. Using data based on the rate of decline over the period 1978-1997, predictions were made of the fate of the trees in the patch. By 2125 only 46 (11% of the 1981 total) salmon gums were predicted to be alive with only one in the “good” category. Only 16 (17%) York gums were predicted to be alive by 2125, with only one in the “good” category. There was no evidence of any regeneration of woodland trees since 1929 when the patch was isolated by clearing for agriculture, and domestic livestock allowed to graze the patch. This deterioration of the dominant trees in the patch is symptomatic of remnant native vegetation over vast areas of Australia's extensively cleared wheat-sheep regions. The future of woodland patches like the one studied is bleak, as is the future of animals dependent on them for food, breeding sites and shelter. Active management, including fencing to exclude domestic livestock and measures to encourage regeneration of native plant communities, is necessary to counter the present regime of benign neglect that characterises most of Australia's management of native vegetation in agricultural landscapes.     

Captive breeding promotes aggression in an endangered Mexican fish

We compared the behaviour of wild and captive-bred butterfly splitfins (Ameca splendens), an endangered freshwater fish, to investigate whether captive breeding results in the behavioural divergence of wild and captive individuals. In a first experiment, we examined whether the captive environment allows for the similar expression of behaviours observed in wild fish. The foraging, courtship and aggressive behaviour of fish in their natural habitat (in Mexico) was compared with that of their counterparts that have been bred at London Zoo, UK, for 40 years. These in situ observations revealed that wild fish were preoccupied with searching for food whereas captive fish engaged more in aggressive interactions. In a subsequent laboratory experiment we compared the behaviour of wild-caught and captive-bred fish under standard conditions in two novel habitats: structured (enriched) and unstructured (bare) aquaria. Overall, captive-bred butterfly splitfins displayed higher levels of aggression than wild-caught fish. The relationship between aggression and habitat structure was influenced by density; captive-bred males were more aggressive when observed in structured habitats than unstructured ones, but only when they were stocked at a high density. We also found an effect of tank structure on foraging behaviour, with individuals spending more time foraging in unstructured tanks than structured tanks. There was no effect of captive breeding or habitat structure on courtship behaviour.Our findings suggest that captive environments can promote the development of aggressive behaviour which may affect the suitability of captive-bred fishes for reintroduction into the wild.     

Distribution of non-native trout in Slovenia and their introgression with native trout populations as observed through microsatellite DNA analysis

In Slovenia, the Adriatic basin inhabited by native marble trout (S. marmoratus), and the Danubian basin inhabited by native Danubian lineage of brown trout (S. trutta) have been intensively affected by stocking with non-native trout strains. In order to assess spread of non-native strains and their introgression with native trout, a population study based on five microsatellite loci was applied across ten marble and ten brown trout populations, ranging from allegedly non-introgressed to heavily managed. On the basis of correspondence analysis, which revealed three clear groupings consisting of the Danubian and Atlantic lineages of brown trout and the marble trout, the alleles, characteristic of each grouping were identified and used for estimating genetic composition of each population according to the three possible origins. Among the wild populations, five marble and one brown trout populations were found to be pure; all the others were introgressed with exotic alleles (Atlantic and marmoratus alleles in the Danubian basin and Atlantic and Danubian in the Adriatic basin) that markedly dominate in intensively managed populations. As revealed by non-significant F_IS values, panmixia between native and introduced fishes has for the most part already been reached. Our research showed that it is not only marble trout whose identity is endangered in Slovenia but also the existence of autochthonous Danubian brown trout is critically compromised, which is new information to be taken into account for local trout conservation.