Establishment of a new breeding colony of Gould’s petrel (Pterodroma leucoptera leucoptera) through the creation of artificial nesting habitat and the translocation of nestlings

Gould’s petrel (Pterodroma leucoptera leucoptera) was restricted, essentially, to a single breeding locality - Cabbage Tree Island, Australia. As a safeguard against extinction, an additional breeding colony was established on nearby Boondelbah Island, where artificial nesting habitat was created by installing 100 plastic nest boxes. Over two years, a total of 200 nestling Gould’s petrels were translocated from Cabbage Tree Island to these boxes. Colonies on both islands were then monitored for a further four years. Selection of nestlings for transfer was based on prior knowledge of growth, plumage development and emergence from the burrow, and aimed to select only birds that were 11-28 days from fledging (DBF) in 1999 and 11-22 DBF in 2000. Of the first 100 nestlings translocated to Boondelbah Island (in March 1999), 95 fledged successfully 8-27 days after transfer (mean = 17.3 days). Of the second 100 nestlings translocated (in March 2000) all successfully fledged 9-22 days after transfer (mean = 15.1 days). The removal of young had no discernible effect on the subsequent breeding productivity of the donor pairs. In all, 41 Gould’s petrels have been recorded at the new colony on Boondelbah Island, where at least 27 nest boxes have been visited. Ten translocated fledglings (nine male, one female) have returned to the translocation site, taking up nest boxes that were, on average, 5.5 m from the box from which they fledged. An additional 27 non-translocated birds, of unknown origin, have also nested in nest boxes on Boondelbah, along with four birds previously known from Cabbage Tree Island. Two nestlings transferred to Boondelbah Island have returned to Cabbage Tree Island. Within five years of the first translocation, the newly established colony on Boondelbah Island has produced a total of 24 eggs and 14 fledglings. The translocation technique developed for Gould’s petrel has broad applicability, being readily adaptable for other burrow-nesting seabirds.     

Fast sinking (integrated weight) longlines reduce mortality of white-chinned petrels (Procellaria aequinoctialis) and sooty shearwaters (Puffinus griseus) in demersal longline fisheries

Longline fisheries have been responsible for the deaths of large numbers of seabirds worldwide. Two of the most difficult seabird species to deter from baited hooks are the white-chinned petrel (Procellaria aequinoctialis) and sooty shearwater (Puffinus griseus). Longlines with integrated weight (IW) sink faster than normal, unweighted (UW), longlines and have the potential to reduce the numbers of these species killed. The relative differences in the number of white-chinned petrels and sooty shearwaters killed on UW longlines and IW longlines containing 50 g/m beaded lead core were investigated in 2002 and 2003 in the New Zealand ling (Genypterus blacodes) autoline fishery. Effects on catch rates of target and non-target fish species, and operational aspects of the use of IW gear, were also assessed. A single bird scaring streamer line was deployed on all sets of longlines. In 2002 and 2003, compared to UW lines IW lines reduced mortality of white-chinned petrels by 98.7% and 93.5%, respectively. In 2003 IW lines reduced sooty shearwater mortality by 60.5%. Catch rates of white-chinned petrels (including on sets when no fatalities were recorded) by IW gear were low: 0.005/1000 hooks (UW: 0.4) and 0.01/1000 hooks (UW: 0.17) in 2002 and 2003, respectively. Equivalent rates for sooty shearwaters in 2003 were 0.06/1000 hooks by IW and 0.13/1000 hooks by UW. No albatrosses were caught on either line type in 2002; in 2003 a single Salvin’s albatross (Thalassarche salvini) was caught on UW gear. Both the number of ling and the mean masses of ling caught in 2003 by IW (mass: 189.3; CL_95% 162.7-220.3 kg/1000 hooks) and UW (200.6; CL_95% 178.2-225.9 kg/1000 hooks) longlines were similar statistically. Use of IW longlines and streamer lines in autoline fisheries should yield major conservation benefits to seabirds interacting with these fisheries worldwide.     

The role of introduced mammals and inverse density-dependent predation in the conservation of Hutton's shearwater

This study investigated the impact of stoat Mustela erminea predation on the endangered Hutton's shearwater Puffinus huttoni. Breeding success of Hutton' shearwaters was significantly lower in two seasons of stoat control than in eight seasons with no control: suggesting that natural environmental variation has a greater influence on breeding success than stoat predation. Monitoring Hutton's shearwaters and mainland colonies of sooty shearwaters Puffinus griseus indicated that small colonies suffered higher predation and lower breeding success than large colonies, demonstrating that predation in these two species is inversely density dependent and explaining the low predation rates observed in the very large Hutton's shearwater colonies. The presence of another introduced predator, feral pigs Sus scrofa, within six extinct colonies of Hutton's shearwaters and at the boundaries of the two extant colonies, strongly suggests that this species was responsible for the historic contraction in breeding range. Controlling stoats within the two remaining colonies is unlikely to assist in the conservation of Hutton's shearwater. Conservation efforts would be better spent protecting the two remaining colonies from pigs and in trying to establish new breeding sites.     

The impact of predation by introduced stoats on Hutton's shearwaters, New Zealand

The Hutton's shearwater Puffinus huttoni is an endangered species of burrowing petrel, that is threatened at its two remaining breeding colonies by the activity of introduced stoats Mustela erminea. Predation of eggs, chicks and adult shearwaters was studied over 10 consecutive breeding seasons (1989/1990-1998/1999) and resident stoats were radio-tracked in two seasons. Stoats were estimated to be killing on average 0.25% of breeding adults and 12% of chicks in each season. Population modeling of Hutton's shearwaters indicated that the estimated impact of this predation was a reduction in the potential yearly population growth rate of 0.86±0.22%. The overall average growth rate derived from the population model of 0.44%, suggests that the population is not in immediate risk of decline and controlling stoats within the colony need not be a priority for management.     

Prioritizing rat eradication on islands by cost and effectiveness to protect nesting seabirds

To prioritize conservation actions on Italian islands we used the case study of the eradication of the Black rat Rattus rattus to protect Cory’s shearwater Calonectris diomedea and Yelkouan shearwater Puffinus yelkouan. We evaluated for each island the effectiveness of rat eradication by means of two different indices, both based on the relative importance of the island’s nesting population of the two species at the national and regional scale, but differing in the parameters set at the divisor, i.e., respectively, the number of nesting pairs in rat-free islands and the number of islands occupied by shearwaters. We estimated analytically the monetary costs of rat eradication on each island. Islands at high risk of recolonization were excluded from further analyses, while costs and effectiveness of rat eradication were compared for the remaining islands. Rat eradication was most cost-effectively carried out on the island hosting the largest colony of P. yelkouan. Eradicating rats from all the islands in the ranking provided benefits to 63.9% of the Italian population of P. yelkouan, but only to 7.1% of that of C. diomedea. Comparing costs and effectiveness of all possible island combinations, ranging from a minimum budget of 50,000 € and a maximum of 1600,000 € (i.e. the cost for eradicating rats from all the listed islands), the maximum increase in effectiveness (marginal effectiveness) fell around a relatively small budget (200,000 €). For both species, when adopting the cost/effectiveness rankings, the number of pairs protected for 1000 € of investment was significantly higher than adopting rankings of effectiveness alone, demonstrating that conservation priorities are more efficiently identified by including monetary costs in the analysis.     

Impact of introduced birds on the recovery of the Tahiti Flycatcher (Pomarea nigra), a critically endangered forest bird of Tahiti

In 1998, only 25 Tahiti Flycatchers (Pomarea nigra), a forest bird endemic to Tahiti (French Polynesia) remained. A recovery programme, aimed at nest protection through both rodent control and tree banding, was initiated. At this time it was supposed that the species was mainly the victim of island infestation by ship rats (Rattus rattus). In the 3 years of this study 54 nests were found and 17 fledged young produced, of which 12 survived the early stage of fledging. Despite an excellent 1999 breeding season and efficient nest protection against rodents, only five of 19 nests produced fledged young in 2000. This was related to higher (P=0.002 and 0.015 respectively) Indian Mynah (Acridotheres tristis) encounters and aggressive interactions in 2000 and 1998 than in 1999. Indian Mynah encounters and interactions were also higher during reproductive activities (and particularly at incubation and nestling stages) in comparison with the non breeding period (P <0.001). In contrast, Red-vented Bulbul (Pycnonotus cafer) encounters and interactions were more uniform throughout. Significantly more Indian Mynah and Red-vented Bulbul were observed in flycatcher territories which experienced nest failure or early fledgling death in comparison with those which experienced reproductive success (P=0.003 and 0.002 respectively). This strongly suggests that these two introduced species represent an important threat to the Tahiti Flycatcher’s survival. Currently, young birds (less than 4 years old) represent 42% of the population, an increase from 12% at the start of the recovery programme.     

Conservation of the dark-rumped petrel Pterodroma phaeopygia in the Galapagos Islands,Ecuador

The effects of predation and habitat deterioration produced by rats, cats, dogs, pigs, goats, burros and cattle, which have been introduced over the last two centuries to the Galapagos archipelago, have reduced the dark-rumped petrel Pterodroma phaeopygia population so that it is now in danger of extinction. By controlling rat numbers through poisoning, and by protecting the nesting colony from other predator and pest species through hunting, petrel breeding success in the Cerro Pajas colony, Floreana Island, has been increased. Preliminary studies indicate that immediate conservation efforts are also needed and are being initiated for at least two other petrel populations. Continued predator control is essential to halt further petrel population declines and to allow their numbers to recuperate.     

Decline in the distribution and abundance of flesh-footed shearwaters (Puffinus carneipes) on Lord Howe Island, Australia

The flesh-footed shearwater (Puffinus carneipes) is a migratory seabird that ranges widely across the Pacific and Indian Oceans. The principal breeding populations are in Australia and New Zealand. The only breeding site in eastern Australia is on Lord Howe Island. Despite it being afforded a high level of legislative protection, the population on Lord Howe Island has declined substantially during the last few decades. The total extent of nesting habitat in 2002 was 24.3 ha, a reduction of 13.4 ha (35.6%) since 1978. Loss of nesting habitat was associated with increased urbanisation, the adverse impact of which extended beyond the footprint of buildings and gardens. In 2002, overall burrow density was 0.123 per m² and the total number of burrows was estimated to be 29,853 ± 5867, a decline of about 19.0% since 1978. A substantial decline in burrow density was evident in the colony where loss of habitat to urbanisation had been greatest. In 2002, 58% of burrows were occupied by breeding birds, and the total population size was estimated to be 17,462 breeding pairs. Breeding success (the proportion of eggs that produced fledglings) was 50%, but was lowest in the most urbanised colony. To avert further declines in the population of flesh-footed shearwaters on Lord Howe Island major changes in land use practices, enforced through appropriate legislation, are needed, together with reductions in the level of seabird bycatch in fisheries operations and in the amount of plastics that litter the world’s oceans.     

Survival of Marbled Teal (Marmaronetta angustirostris) released back into the wild

Reintroduction or re-enforcement programmes are major tools in species conservation, but there is a need for more studies that assess the influence of different husbandry and release methods on the survival of released animals. We investigated the survival of globally threatened Marbled Teal (Marmaronetta angustirostris) taken into captivity as ducklings when they became trapped in an irrigation channel, then released again after fledging. We used wing tags and mark-recapture models to estimate the survival of released teal. Ducklings rescued in 1996 (n = 53) were released soon after fledging in September and their survival was modelled for seven months until April 1997. Their apparent monthly survival rate (lower than true survival owing to loss of wing tags) was 0.85 ± 0.12 (±s.e.). Ducklings rescued in 1997 (n = 44) were released together in February 1998 over five months after fledging, and their survival was modelled for six months from February until August. Their apparent monthly survival rate was 0.54 ± 0.06. Ducklings rescued in 1998 (n = 159) were released in August-September soon after fledging and their survival was modelled for 10 months from August until June. Their apparent monthly survival rate was 0.83 ± 0.07. Monthly survival was significantly higher for the 1996 and 1998 cohort, suggesting that retaining birds in captivity after fledging had a negative impact on post-release survival. When birds were released in February, a lower proportion survived until the breeding season three months later than when they were released five months earlier in September.     

The impact of pelagic longline fishing on the flesh-footed shearwater Puffinus carneipes in Eastern Australia

The flesh-footed shearwater (Puffinus carneipes) is a medium-sized seabird (ca. 700 g) that is incidentally killed during longline fishing operations. We examined the levels of bycatch in Australia’s Eastern Tuna and Billfish Fishery and developed a model to examine the impact of this fishery on the eastern Australian population of flesh-footed shearwaters, which breeds at only one site, Lord Howe Island. Observed bycatch rates for flesh-footed shearwaters were 0.378 birds/1000 hooks for night sets, and 0.945 birds/1000 hooks for day sets. The mean number of birds killed from 1998 to 2002 was estimated to be 1794-4486 birds per year, with the estimated total killed over this period ranging from 8972 to 18,490 birds. Models incorporating both density-independent and density-dependent scenarios were applied to levels of bycatch representative of that observed in the fishery. Density-independent scenarios showed that fishing mortality levels caused declines in the majority of simulated populations. In contrast, density-dependent scenarios produced populations that were more resilient to fishing mortalities. Although some modelling scenarios led to population growth, under most stochastic simulations median population halving and quasi-extinction times were less than 55 and 120 years, respectively. We conclude that the level of bycatch observed in the fishery is most likely unsustainable and threatens the survival of the Lord Howe Island population. This situation can be improved only with the development and implementation of mitigation measures that will halt or greatly reduce the level of bycatch currently observed. Improved knowledge on a range of demographic parameters for the species, combined with a clearer idea of the at-sea distribution of breeding and non-breeding shearwaters, will greatly assist in improving understanding and the management of this population.     

The importance of secondary forest blocks for terrestrial mammals within an Acacia/secondary forest matrix in Sarawak, Malaysia

With the rapid conversion of tropical forests in Asia to plantation forests for timber or biofuel production there is a need to determine if these forests serve any viable role in wildlife conservation. We used infra-red trip cameras to survey for large terrestrial mammals within an Acacia/secondary forest matrix being created for pulpwood production in Sarawak, Malaysia. We detected at least 27 species of mammals within the matrix and 18 species were detected in both Acacia and secondary forest. Using occupancy modeling to determine important covariates for seven mammal species within the project area, six of these species were sensitive to forest type, and most were sensitive to the amount of secondary forest within 1 km of the sample point. For four species (sun bear, Helarctos melayanus; common porcupine, Hystrix brachyura; mousedeer, Tragulus spp.; and pig-tailed macaque, Macaca nemestrina), the mean distance of detection from large secondary forest blocks was significantly closer than expected from the distribution of sample points. Most species used Acacia forest less frequently than secondary forest, possibly for transit or foraging, with the exception of bearded pigs (Sus barbatus), sambar (Rucervus unicolor), and civets which were more common in Acacia stands. The amount of secondary forest preserved within forest plantations seems to be the best measure of conservation potential for these industrial forests. Forest plantations can provide a conservation value if managed properly and those retaining significant amounts of secondary forest should be eligible for a base level of certification as they comprise a significant portion of the landscape in this region.     

Estimating incidental takes of shearwaters in driftnet fisheries: lessons for the conservation of seabirds

We consider estimation of the magnitude of incidental fisheries ‘bycatch’ for two petrel species, sooty shearwaters (Puffinus griseus) and short-tailed shearwaters (Puffinus tenuirostris). There are clear statistical advantages in estimating bycatch for abundant species such as these, and our results may also guide the conservation and management of rarer species. We used fisheries statistics and observer data to estimate retrospectively the total numbers of sooty and short-tailed shearwaters bycatch in seven large-scale pelagic North Pacific driftnet fisheries between 1952 and 2001. Sensitivity analysis greatly simplified estimation of uncertainty by identifying four driftnet fisheries to be of particular importance in determining the magnitude and precision of the estimated bycatch totals. We estimated that between 1.0 and 12.8 million (95% CI) sooty shearwaters were killed by driftnets between 1952 and 2001. For short-tailed shearwaters we estimated between 4.6 and 21.2 million (95% CI) over the same period. More precise estimation was hampered by the paucity of available observer data, lack of reported detail and inconsistencies among data sources. Estimates may be strongly biased because some dead birds are misidentified or drop out of nets before hauling, or because some records were of live captures that were subsequently released. Improved estimation of overall take and its impact on populations of seabirds requires standardisation of reporting, allowance for potential sampling bias, as well as a clearer definition of the sampling unit and underlying bycatch probability distribution model, and knowledge of potential compensatory changes in population parameters.     

Community and ecosystem consequences of giant knotweed (Polygonum sachalinense) invasion into riparian forests of western Washington, USA

The invasive, non-native herb, giant knotweed (Polygonum sachalinense), is becoming increasingly common in riparian corridors throughout North America and Europe. Despite its prevalence, there has been limited study of its ecological impacts. We investigated the effects of knotweed invasion on the abundance and diversity of forest understory plants, and the quantity and nutrient quality of leaf-litter inputs, in riparian forests in western Washington, USA. Among 39 sampling locations, knotweed stem density ranged from 0 to 8.8 m⁻². Richness and abundance (cover or density) of native herbs, shrubs, and juvenile trees (?3 m tall) were negatively correlated with knotweed density. Where knotweed was present (>5.3 stems m⁻²), litter mass of native species was reduced by 70%. Carbon:nitrogen ratio of knotweed litter was 52:1, a value 38-58% higher than that of native woody species (red alder [Alnus rubra] and willow [Salix spp.]). Resorption of foliar N prior to leaf drop was 76% in knotweed but only 5-33% among native woody species. By displacing native species and reducing nutrient quality of litter inputs, knotweed invasion has the potential to cause long-term changes in the structure and functioning of riparian forests and adjacent aquatic habitats.     

Distribution of monoterpenes between organic resources in upper soil horizons under monocultures of Picea abies, Picea sitchensis and Pinus sylvestris

The aim of this study was to compare the monoterpene content and distribution in litters and roots of three conifer species: Picea abies (L.) Karst, Picea sitchensis (Bong.) Carr. and Pinus sylvestris (L.). We analysed the monoterpene content of green needles, needle litter, F (fermentation) layer material and roots collected from monoculture plots. The rate of loss of monoterpenes from freshly fallen litter in the field was also studied at two monthly intervals over 10 months, to assess the length of time that monoterpenes entering the litter layer remain. Monoterpene analysis was carried out by extracting homogenised samples in hexane and identifying and quantifying the resulting monoterpenes using gas chromatography with flame ionisation detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Mean total monoterpene concentrations varied significantly between the three species examined (e.g. in freshly fallen litter 1531 ± 96, 100 ± 5 and 1175 ± 122 μg g⁻¹ d. wt for P. abies, P. sitchensis and P. sylvestris); each species had distinctive and consistent monoterpene profiles associated with each type of tissue, and total monoterpene concentrations in green needles varied between individual trees of the same species, particularly for P. sitchensis. A substantial proportion of the monoterpene content of green needles remained in the needles after litter fall for P. abies (42%), P. sitchensis (11%) and P. sylvestris (30%). Although rates of monoterpene loss from needle litters varied initially (P. sylvestris > P. abies > P. sitchensis), the majority of the monoterpene content was lost after 4-6 months. Maximum monoterpene emission rates from decaying litter were calculated of 39 (P. abies), 1.7 (P. sitchensis) and 39 μg m⁻² h⁻¹ (P. sylvestris). Monoterpene concentrations in F layer material were very low (<10 μg g⁻¹ d. wt). Roots, particularly in P. sylvestris, represented a significant pool of monoterpenes (185 ± 16, P. abies; 258 ± 54, P. sitchensis; 2133 ± 200 μg g⁻¹ d. wt, P. sylvestris). The monoterpene profile was similar between roots and litter of P. sylvestris (α-pinene most abundant), and for P. sitchensis, (limonene and α-pinene most abundant), although a different pattern was observed between needle litter (most abundant β-pinene) and roots (most abundant myrcene) of P. abies. The relatively high concentrations and different profiles of monoterpenes characterised in upper organic soil horizons here emphasise the need for their influence on soil ecological processes to be assessed.     

Facilitating the evolution of resistance to avian malaria in Hawaiian birds

Research has shown that avian malaria plays an important role in limiting the distribution and population sizes of many Hawaiian birds, and that projected climate change is likely to eliminate most disease-free habitat in Hawai’i in the next century. I used a modeling approach, parameterized with demographic data from the literature and the field, to examine alternate management scenarios for the conservation of native Hawaiian birds. I examined the feasibility of using management in the form of rodent control to facilitate the evolution of resistance to malaria by increasing the survival and reproduction of native birds. Analysis of demographic data from seven native species, Akepa (Loxops coccineus), ‘Akohekohe (Palmeria dolei), Elepaio (Chasiempis sandwichensis), Hawai’i’amakihi (Hemignathus virens), Hawai’i creeper (Oreomystis mana), Omao (Myadestes obscurus), and Palila (Loxioides bailleui), suggest that differences in life history cause some species to be more susceptible to local extinctions from the transmission of malaria. Modeling results demonstrated that rodent control at middle, but not high, elevations can facilitate the evolution of resistance to malaria in several species of Hawaiian birds. Advocating a management approach that encourages evolutionary change in endangered species contrasts with the traditional conservation paradigm but it may be the best strategy to reduce the impacts of one of the multiple stressors that have devastated the native bird community of Hawai’i.     

The influence of food availability on breeding success of African penguins Spheniscus demersus at Robben Island, South Africa

From 1989 to 2004, the breeding success of African penguins Spheniscus demersus at Robben Island, South Africa was significantly related to estimates of the abundance of both their main prey species, anchovy Engraulis encrasicolus and sardine Sardinops sagax, and to the combined biomass of these species. When the combined spawner biomass of fish prey was less than 2 million ton, pairs fledged an average of 0.46 chicks annually. When it was above 2 million ton, annual breeding success had a mean value of 0.73 chicks per pair. Given previously estimated values of survival and age at first breeding, these levels of breeding success are inadequate to sustain the African penguin population. With the higher level of breeding success, an equilibrium situation might be attained if adult survival could be increased by 6-7% per annum. Attempts to reduce mortality of penguins have included the collection, cleaning and return to the wild of oiled birds, culling of Cape fur seals Arctocephalus pusillus pusillus seen preying on penguins around breeding localities and control of the spread of disease. Management of the purse-seine fishery should ensure adequate escapement of fish to maintain the combined biomass of anchovy and sardine above 2 million ton. The maintenance of suitable breeding habitat and removal of feral predators from breeding localities will also be important in improving breeding success.     

Terrestrial vertebrate communities at black-tailed prairie dog (Cynomys ludovicianus) towns

We capitalized on a regional-scale, anthropogenic experiment—the reduction of black-tailed prairie dog (Cynomys ludovicianus) towns across the Great Plains of North America—to test the hypothesis that decline of this species has led to declines in diversity of native grassland vertebrates of this region. We compared species richness and species composition of non-volant mammals, reptiles and amphibians at 36 prairie dog towns and 36 paired sites in the Panhandle Region of Oklahoma during the summers and falls of 1997, 1998 and 1999. We detected 30 species of mammals, 18 species of reptiles and seven species of amphibians. Comparisons between communities at prairie dog towns and paired sites in the adjacent landscape indicated that while richness per se was not necessarily higher in towns, they did harbor significantly more rare and imperiled species. Species that were positively associated with prairie dog towns during one or both seasons (summer and fall) included badgers (Taxidea taxus), eastern cottontails (Sylvilagus floridanus), coyotes (Canis latrans), grasshopper mice (Onychomys leucogaster), swift fox (Vulpes velox), pronghorn antelopes (Antilocapra americana), striped skunks (Mephitis mephitis), white-tailed deer (Odocoileus virginianus), cattle, thirteen-lined ground squirrels (Spermophilus tridecemlineatus), black-tailed jackrabbits (Lepus califonicus), barred tiger salamanders (Ambystoma tigrinum), plains spadefoot toads (Scaphiopus bombifrons), Great Plains toad (Bufo cognatus), Woodhouse's toad (Bufo woodhousii), prairie rattlesnakes (Crotalis viridis), western plains garter snakes (Thamnophis radix), Texas horned lizards (Phrynosoma cornutum), and ornate box turtles (Terrapene ornata).     

Effect of Carpobrotus spp. on the pollination success of native plant species of the Balearic Islands

Invasive plant species are often considered as potential competitors of native species due to their usually greater capacity for colonization and expansion, but we still have scarce information on whether invasives can also compete for pollination services with natives. In the present study, we hypothesized that the showy flowers of the highly invasive Carpobrotu spp. can compete with native species (Cistus monspeliensis, Cistus salviifolius, Anthyllis cytisoides and Lotus cytisoides) with which it shares habitat and flowering time, influencing pollinator visitation. To test this, we censused insects visiting the flowers of native species in the field and recorded the number of flowers visited in adjacent areas with and without the presence of Carpobrotus. We also assessed the presence of exotic pollen on stigmas of native species and evaluated its effect on reproduction. We detected potential competition for pollinators only in one native species (L. cytisoides), a facilitative effect in two other species (C. salviifolius and A. cytisoides), and a neutral effect in a fourth one (C. monspeliensis). Moreover, such effects appear not to be consistent in time. The presence of Carpobrotus pollen on native stigmas was almost negligible, and hand-pollination experiments showed that such exotic pollen does not interfere significantly with native pollen, not affecting seed set. Our results indicate that the role of the invasive Carpobrotus in promoting or constraining the natural pollination dynamics is likely to have species specific effects on the native flora.     

Life on the edge - High levels of genetic diversity in a cliff population of Bertya ingramii are attributed to B. rosmarinifolia (Euphorbiaceae)

Wind-facilitated migration of new genotypes into small, geographically disjunct populations should buffer them against local extinction. Bertya ingramii, a monoecious, wind-pollinated shrub, is restricted to three populations in a 4 km² area in eastern Australia. Populations are separated by deeply dissected gorges where it is unlikely that seeds are exchanged but where wind movement may facilitate pollen dispersal. Using 156 highly polymorphic ISSR markers, we found moderate genetic variation within and among populations of B. ingramii and less genetic diversity in a nearby and small population of the widespread Bertya rosmarinifolia. The smallest population of B. ingramii (<30 plants) had the highest genetic variation (65% polymorphic markers, Shannon Information Index = 0.30). AMOVA and a Bayesian analysis showed that molecular variance was equally distributed within and among populations suggesting that gene flow is as limited within as in among populations. Genetic distances between populations were only weakly explained by their relative geographic distances (mantel test, R² = 0.21, P = 0.001) but the distribution of private bands, the departure from Hardy-Weinberg equilibrium, and a UPGMA tree showed that the smallest population of B. ingramii was generally more similar to an upstream population of B. rosmarinifolia. Thirty-eight percent of bands in this small population of B. ingramii were exclusively shared with B. rosmarinifolia. This covert hybridisation may have been an ancient event but may be responsible for contemporary declines in germination and establishment in B. ingramii. The conservation implications are amplified by the endangered status of B. ingramii.     

Successful reintroductions of the endangered long-lived Sargent’s cherry palm, Pseudophoenix sargentii, in the Florida Keys

The 1991-1994 reintroductions of Florida endangered Pseudophoenix sargentii to 13 Florida Keys sites represent a rare example of a successful multi-agency long-term effort to conserve a long-lived palm. To assess reintroduction success, we compared population demographics with and without reintroduced plants and conducted population viability analyses. Since 1991, the wild population has increased 6.4-fold. Survival from 2000-2004 was 94%, growth was positive (λ = 1.013), and there was no predicted extinction risk. Recent wild population growth is attributed to good seedling recruitment and removing the greatest threats. After 14 years, reintroductions had 43% survival, increased total plants in the wild by 27%, and expanded the species’ distribution. Reintroduced plants had faster maturation rates, improved population age structure, and enhanced population growth (λ = 1.032). Success varied with transplant year, location, microsite, and original transplant size. Failures in 1991 and at some historic sites emphasize the need for a multi-year, multi-site approach to reintroductions to buffer against stochastic losses. Rockland hammocks and the tops of coastal berms had greatest plant growth and survival. Large transplants had the greatest survival. Because no reintroduced plants are reproductive, transitions between stages are extremely slow, and plants may require >30 years to mature, continued institutional dedication to long-term monitoring will be required to assess whether the populations are self-sustaining. Horticultural expertise and ex situ collections complimented support of land managing agencies for the species’ preservation. These first rare plant reintroductions to Florida State Parks opened avenues for more plant conservation efforts and public interpretation.