Concentrations and distribution of 210Pb in bird feathers and its potential for tracing age and flight times.

Bird feathers have been widely used as environmental indicators, providing key information on environmental pollution. However, there is little available information on the adsorption of natural radioactivity in bird feathers and consequently, its impact on the field of movement ecology is not yet known. This study investigates the concentration and distribution of 210Pb in wing- and tail-feathers of different bird species with contrasting migratory strategies, and discusses its potential use as a tracer of age and flight times. Adsorption of 210Pb in bird feathers is directly related to the interaction of feathers with air, therefore it is hypothesised that the presence of this radionuclide is proportional to the length of flight times, and is asymmetrically distributed in flight feathers. Consequently, a significant difference is expected between 210Pb concentrations in feathers of long-distance migrants when compared to sedentary species. For this purpose, a total of 45 samples from eight individuals of three bird species with distinct migratory strategies were analysed: a highly aerial and long-distance migratory species (Common swift Apus apus), and two largely sedentary species widely distributed across Europe (Great tit Parus major and Tawny owl Strix aluco). Novel findings show that the content of 210Pb in bird feathers of adult migratory birds is much higher than in sedentary birds or juvenile individuals, demonstrating this naturally occurring radionuclide can provide information about the contact time between feathers and air. Additionally, 210Pb adsorption was not evenly distributed in bird feathers. The findings provide a new method to trace age and flight time of birds using 210Pb in feathers, complementing conventional techniques in bird migration studies.

Ecological conditions in wintering and passage areas as determinants of timing of spring migration in trans-Saharan migratory birds.

1. Climate change has been associated with shifts in the timing of biological events, including the spring arrival of migratory birds. Early arrival at breeding sites is an important life-history trait, usually associated with higher breeding success and therefore, susceptible to selection and evolution in response to changing climatic conditions. 2. Here, we examine the effect of changes in the environmental conditions of wintering and passage areas on the mean passage time of 13 trans-Saharan passerines during their spring migration through the western Mediterranean over the 15 years from 1993 to 2007. 3. We found that most of the species studied have been advancing the timing of their passage in recent years. However, annual variation in the mean date of passage was positively correlated with vegetation growth (measured as the normalized difference vegetation index [NDVI]) both in the Sahel (the region of departure) and in northern Africa (the passage area). Thus, migration dates were delayed in years with high primary productivity in passage and wintering zones. All species seem to respond similarly to NDVI in the Sahel; however, late migrants were less affected by ecological conditions in northern Africa than those migrating earlier, suggesting differences based on species ecology. 4. Mean timing of passage was not related to the North Atlantic Oscillation (NAO), El Niño-Southern Oscillation (ENSO), temperature or NDVI in the species-specific wintering areas (the overwintering region) when analysed in combination with the other covariates. 5. Our findings show that ecological conditions in the winter quarters (specifically the Sahel) and en route are relevant factors influencing trends in the passage dates of trans-Saharan migratory birds on the southern fringe of Europe. Possible long-term consequences for late arriving spring migrants are discussed.

The influence of wind direction on the capture of the wood warbler (Phylloscopus sibilatrix), an uncommon migratory species in the western Mediterranean.

The wood warbler (Phylloscopus sibilatrix) is a migratory species in the western Mediterranean wintering in the Gulf of Guinea region, West Africa. In autumn and spring, this species, along with the populations breeding in Ireland and Britain, uses the Italian peninsula as its main axis of migration. From the data of captured birds at several ringing stations in the western Mediterranean (Balearic Islands and coastal Iberian Peninsula), we analyzed capture rates of the species during spring migration from 1993 to 2007. Based on the selection of days with a significant number of captures and those without captures, we analyzed the effect of wind direction over the western Mediterranean to determine a relationship between winds and the number of captures. From a total of 663 wood warblers captured between 1993 and 2007, a total of 31 days have been selected as significant days with a high number of captures, and 31 days have been selected as no-capture days. On days of maximum captures, winds coming from an easterly direction, i.e. Algeria and Tunisia, were dominant, indicating days with a clear eastern component. Contrary to expected results, captures were also made on days when the wind direction was predominantly from a northerly direction. Analysis of the origin of the winds in north eastern Spain (western Mediterranean) revealed that the majority of northerly winds originated from Africa and not from Europe as is usual for this region. Days or periods selected as no-capture days were characterized by winds coming from a northerly (European origin) or westerly direction.

Soil organic carbon accumulation rates on Mediterranean abandoned agricultural lands.

Secondary succession on abandoned agricultural lands can produce climate change mitigation co-benefits, such as soil carbon sequestration. However, the accumulation of soil organic carbon (SOC) in Mediterranean regions has been difficult to predict and is subject to multiple environmental and land management factors. Gains, losses, and no significant changes have all been reported. Here we compile chronosequence data (n = 113) from published studies and new field sites to assess the response of SOC to agricultural land abandonment in peninsular Spain. We found an overall SOC accumulation rate of +2.3% yr-1 post-abandonment. SOC dynamics are highly variable and context-dependent. Minimal change occurs on abandoned cereal croplands compared to abandoned woody croplands (+4% yr-1). Accumulation is most prevalent within a Goldilocks climatic window of ~13-17 °C and ~450-900 mm precipitation, promoting >100% gains after three decades. Our secondary forest field sites accrued 40.8 Mg C ha-1 (+172%) following abandonment and displayed greater SOC and N depth heterogeneity than natural forests demonstrating the long-lasting impact of agriculture. Although changes in regional climate and crop types abandoned will impact future carbon sequestration, abandonment remains a low-cost, long-term natural climate solution best incorporated in tandem with other multipurpose sustainable land management strategies.

The Influence of Markets on the Nutrition Transition of Hunter-Gatherers: Lessons from the Western Amazon.

For many centuries, hunter-gatherer societies relied on subsistence practices and traditional diets. However, forces of globalization have increased market involvement, thereby fueling the nutrition transition of hunter-gatherer societies. We review the academic literature on market involvement of hunter-gatherer societies in the Western Amazon and its consequences on diet, health and well-being. First, we elaborate on four main determinants of market involvement (accessibility, monetary income, wild meat trade and social capital), showing how each determinant draws individuals toward or away from markets. Thereafter, we discuss how these determinants alter diet, health and well-being. Our results add to the understanding of the complex relations between market involvement, dietary change, health and well-being of indigenous societies. Furthermore, they bring to light that additional research is needed on the topic to support decision-makers and help preserve indigenous values.