Direct and indirect effects of rats: does rat eradication restore ecosystem functioning of New Zealand seabird islands?

Introduced rats (Rattus spp.) can affect island vegetation structure and ecosystem functioning, both directly and indirectly (through the reduction of seabird populations). The extent to which structure and function of islands where rats have been eradicated will converge on uninvaded islands remains unclear. We compared three groups of islands in New Zealand: islands never invaded by rats, islands with rats, and islands on which rats have been controlled. Differences between island groups in soil and leaf chemistry and leaf production were largely explained by burrow densities. Community structure of woody seedlings differed by rat history and burrow density. Plots on islands with high seabird densities had the most non-native plant species. Since most impacts of rats were mediated through seabird density, the removal of rats without seabird recolonization is unlikely to result in a reversal of these processes. Even if seabirds return, a novel plant community may emerge.     

Traditional Medicine and Childcare in Western Africa: Mothers’ Knowledge,Folk Illnesses,and Patterns of Healthcare-Seeking Behavior

Background

In spite of the strong role of traditional medicine in childcare in the pluralistic healthcare system in Western Africa, little information is known on mothers’ domestic plant knowledge. Identifying local perspectives and treatments of children’s illnesses, including folk illnesses, is essential to having a comprehensive understanding of how mothers make healthcare treatment decisions. We aimed to identify which infant illnesses Beninese and Gabonese mothers knew to treat with medicinal plants and for which illnesses they sought biomedical care or traditional healers.

Methods

We conducted 81 questionnaires with mothers in Bénin and Gabon and made 800 botanical specimens of cited medicinal plants. We calculated the number of species cited per illness and the proportion of participants knowledgeable on at least one herbal remedy per illness. Using qualitative data, we described folk illnesses in each country and summarized responses on preferences for each of the three healthcare options.

Results

Participants from both countries were most knowledgeable on plants to treat respiratory illnesses, malaria, diarrhea, and intestinal ailments. Mothers also frequently mentioned the use of plants to encourage children to walk early, monitor the closure of fontanels, and apply herbal enemas. Major folk illnesses were atita and ka in Bénin and la rate and fesses rouges in Gabon. Traditional healers were reported to have specialized knowledge of cultural bound illnesses. Malaria was frequently cited as an illness for which mothers would directly seek biomedical treatment.

Conclusion

Mothers largely saw the three systems as complementary, seamlessly switching between different healing options until a remedy was found. Folk illnesses were found to give insight into local treatments and may reveal important neglected diseases. Due to high reported levels of knowledge on treating top statistical causes of infant mortality and folk illnesses, mothers’ medicinal plant knowledge should be included in the analysis of healthcare-seeking behavior for childcare.     

Above- and below-ground impacts of introduced predators in seabird-dominated island ecosystems

Predators often exert multi-trophic cascading effects in terrestrial ecosystems. However, how such predation may indirectly impact interactions between above- and below-ground biota is poorly understood, despite the functional importance of these interactions. Comparison of rat-free and rat-invaded offshore islands in New Zealand revealed that predation of seabirds by introduced rats reduced forest soil fertility by disrupting sea-to-land nutrient transport by seabirds, and that fertility reduction in turn led to wide-ranging cascading effects on belowground organisms and the ecosystem processes they drive. Our data further suggest that some effects on the belowground food web were attributable to changes in aboveground plant nutrients and biomass, which were themselves related to reduced soil disturbance and fertility on invaded islands. These results demonstrate that, by disrupting across-ecosystem nutrient subsidies, predators can indirectly induce strong shifts in both above- and below-ground biota via multiple pathways, and in doing so, act as major ecosystem drivers.     

Reproduction and growth of the black shore skink,Leiolopisma suteri (Lacertilia: Scincidae), in north‐eastern New Zealand

Reproduction and growth of a boulder beach population of the nocturnal skink Leiolopisma suteri on Motutapu Island were studied for 19 months. Epididymes contain sperm from April to November, and copulation probably occurs in October or November (spring). Ovulation occurs in late October or early November, and three or four (mean, 3.7) eggs are laid in late December. Incubation takes 3 months. Total development time from ovulation to hatching is 5 months, one of the longest development periods recorded for Scincidae. Growth to sexual maturity is slow, most females depositing their first clutch 33 months after hatching; males mature at 29 months.     

Deciding when to lend a helping hand: a decision-making framework for seabird island restoration

Following the removal of an introduced species, island restoration can follow two general approaches: passive, where no further intervention occurs and the island is assumed to recover naturally, and; active, where recovery of key taxa (e.g. seabirds) is enhanced by manipulating movement and demography. Steps for deciding between these techniques are: (1) outlining an explicit restoration goal; (2) building a conceptual model of the system; (3) identifying the most effective management approach; and (4) implementing and monitoring outcomes. After decades of island restoration initiatives, retrospective analysis of species’ responses to active and passive management approaches is now feasible. We summarize the advantages of incorporating these analyses of past restoration results as an initial step in the decision-making process. We illustrate this process using lessons learned from the restoration of seabird-driven island ecosystems after introduced vertebrate eradication in New Zealand. Throughout seven decades of successful vertebrate eradication projects, the goals of island restoration have shifted from passive to active enhancement of island communities, which are heavily dependent on burrow-nesting petrel population recovery. Using a comparative analysis of petrel response to past predator eradications we built a conceptual model of petrel recovery dynamics and defined key site and species characteristics for use in a stepwise decision tree to select between active or passive seabird population management. Active restoration techniques should be implemented when seabird populations are absent or declining; and on islands with no nearby source colony, small remnant colonies, highly altered habitat with shallow soil and slopes, and with competitive species pairs. As we continue to restore complex island communities, decision-making tools using a logical, step-wise framework informed by previous restoration successes and failures can aid in increasing understanding of ecosystem response.     

Key biocultural values to guide restoration action and planning in New Zealand

A pluralist and cross‐cultural approach that accommodates differing values while encouraging the collaboration and social cohesion necessary for the complex task of ecological restoration is needed. We used qualitative and quantitative analyses to investigate value assigned to biocultural restoration of coastal forests in northern New Zealand by 26 interviewees from three groups (environmental managers, Māori community members, and community project leaders). Māori community members primarily emphasized the importance of Cultural Stewardship and Use in the restoration process, while placing less emphasis on Ecological Integrity. Otherwise, all participants shared common trends, culminating in three interrelated value sets: (1) Personal Engagement, (2) Connection, and (3) the generation and transfer of Knowledge & Wisdom. These values demonstrate that restoration's benefits to people and community are as significant as its reparations of ecological components. Despite differences, all stakeholders were united in a broadly common goal to restore socio‐ecological systems. Their knowledge and shared passion for conservation signal enormous promise for accelerated and effective restoration of coastal forests, if it is conducted using a pluralistic approach. Because some values expressed were intangible and complex, with cross‐cultural dimensions, current valuation tools used by ecological economists to guide management investment fail to adequately account for, in particular, Māori values of ecological restoration.     

Differences between neurological and neurosurgical approaches in the management of malignant brain tumours.

The management and outcome in 205 patients diagnosed as having cerebral gliomas over five years were reviewed. Patients referred to neurologists and neurosurgeons had similar clinical features and similar results on computed tomography. Patients referred to neurologists underwent burr hole biopsy less often and had better short term morbidity than patients referred to neurosurgeons, although final outcome was the same in both groups. Few patients underwent other surgical procedures. Referral for radiotherapy was usually by neurosurgeons, although this did not significantly affect long term survival. The implications for the management of patients with primary malignant brain tumours and the need for prospective studies are discussed.     

Predation of seabirds by invasive rats: multiple indirect consequences for invertebrate communities

Invasive species are a global problem but most studies have focused on their direct rather than indirect ecological effects. We studied litter and soil‐inhabiting invertebrate communities on 18 islands off northern New Zealand, to better understand the indirect ecological consequences of rat (Rattus) invasion. Nine islands host high densities of burrowing procellariid seabirds that transport large amounts of nutrients from the ocean to the land. The other nine have been invaded over the past 50–150 years by rat species that have severely reduced the density of seabirds by preying on eggs and chicks. Invaded islands had lower densities of seabird burrows but deeper forest litter than did the uninvaded islands, indicative of rats reducing disturbance effects of seabirds. However, despite deeper litter on the invaded islands, eight of the 19 orders of invertebrates that we measured were significantly less abundant on invaded islands. Furthermore, three soil‐inhabiting micro‐invertebrate groups that we measured were significantly less abundant on invaded islands. These differences probably result from rats thwarting transfer of resources by seabirds from the ocean to the land. We also investigated community‐level properties of each of three test groups of invertebrates (minute land snails, spiders and soil nematodes) to illustrate this process. Spiders were equally abundant on both groups of islands, but showed lower species richness on the invaded islands. The other two groups showed no difference in species richness with island invasion status, but were more abundant on uninvaded islands. Reduced abundance of soil nematodes on invaded islands provides strong evidence of indirect consequences of seabird reduction by rats, because nematodes are unavailable to rats as prey. We predict that if rats are eradicated from islands, components of below‐ground invertebrate dependent on seabird‐mediated soil conditions may take considerable time to recover because they require subsequent seabird recolonisation.