Telomere length (TL) has been shown to be a potential predictor of survival in wild vertebrates, and, as a consequence, there is growing interest in understanding the causes of inter-individual variability in TL. In that context, developmental conditions deserve a specific attention because they are thought to be a major driver of telomere shortening. Because poor developmental conditions can accelerate telomere shortening and impair growth (resulting in a small adult size), a positive correlation between TL and body size is expected. However, and surprisingly, the relationship between body size and telomere length has rarely been described in wild vertebrates. Here, we specifically examined this question in hatch-year (HY) and after hatch-year (AHY) male wintering American Redstarts (Setophaga ruticilla). Although tarsus size was not related to TL, we found a significant positive correlation between bill size and TL in HY male Redstarts, therefore supporting the idea that determinants of some components of individual size are also important determinants of TL in young birds. Moreover, this positive relationship between bill size and TL was also found for AHY birds, suggesting that adult TL may be, at least partly, explained by the telomere dynamics that occurred during the developmental phase.

Disease represents a strong driving force of societal and cultural change, which repeats itself today. During the 14th century, the Plague ravaged Europe, and fear of illness, destruction, and hopelessness changed society. Fear of the Plague altered the religious climate of the entire continent and drove many to commit acts of violence. Lack of knowledge about the Plague changed the way medicine was taught and practiced, moving towards modern medicine. Governments began to take a more active role in the health of the citizens, and national legislation began having greater impacts at the local level. The centuries old economic structure began to crumble, setting the stage for more balanced, free-market trade. Those factors—mentality, medicine, law, and economics—elicited similar reactions in the 2014 Ebola Outbreak. Fear of Ebola resulted in violence. Medical researchers were inspired by the outbreak to learn more about Ebola and are looking for potential cures and vaccines. Laws restricting travel and advocating healthy practices dominated the infected countries. The economies of the diseased areas suffered. Little has changed in the nature of people in medieval Europe and today; though centuries have passed, societies respond to disease in the same fundamental ways. Disease represents a strong driving force of societal and cultural change, which repeats itself today. During the 14th century, the Plague ravaged Europe, and fear of illness, destruction, and hopelessness changed society. Fear of the Plague altered the religious climate of the entire continent and drove many to commit acts of violence. Lack of knowledge about the Plague changed the way medicine was taught and practiced, moving towards modern medicine. Governments began to take a more active role in the health of the citizens, and national legislation began having greater impacts at the local level. The centuries old economic structure began to crumble, setting the stage for more balanced, free-market trade. Those factors—mentality, medicine, law, and economics—elicited similar reactions in the 2014 Ebola Outbreak. Fear of Ebola resulted in violence. Medical researchers were inspired by the outbreak to learn more about Ebola and are looking for potential cures and vaccines. Laws restricting travel and advocating healthy practices dominated the infected countries. The economies of the diseased areas suffered. Little has changed in the nature of people in medieval Europe and today; though centuries have passed, societies respond to disease in the same fundamental ways.

Global maize production alters an enormous soil organic C (SOC) stock, ultimately affecting greenhouse gas concentrations and the capacity of agroecosystems to buffer climate variability. Inorganic N fertilizer is perhaps the most important factor affecting SOC within maize-based systems due to its effects on crop residue production and SOC mineralization. Using a continuous maize cropping system with a 13 year N fertilizer gradient (0–269 kg N ha⁻¹ yr⁻¹) that created a large range in crop residue inputs (3.60–9.94 Mg dry matter ha⁻¹ yr⁻¹), we provide the first agronomic assessment of long-term N fertilizer effects on SOC with direct reference to N rates that are empirically determined to be insufficient, optimum, and excessive. Across the N fertilizer gradient, SOC in physico-chemically protected pools was not affected by N fertilizer rate or residue inputs. However, unprotected particulate organic matter (POM) fractions increased with residue inputs. Although N fertilizer was negatively linearly correlated with POM C/N ratios, the slope of this relationship decreased from the least decomposed POM pools (coarse POM) to the most decomposed POM pools (fine intra-aggregate POM). Moreover, C/N ratios of protected pools did not vary across N rates, suggesting little effect of N fertilizer on soil organic matter (SOM) after decomposition of POM. Comparing a N rate within 4% of agronomic optimum (208 kg N ha⁻¹ yr⁻¹) and an excessive N rate (269 kg N ha⁻¹ yr⁻¹), there were no differences between SOC amount, SOM C/N ratios, or microbial biomass and composition. These data suggest that excessive N fertilizer had little effect on SOM and they complement agronomic assessments of environmental N losses, that demonstrate N₂O and NO₃ emissions exponentially increase when agronomic optimum N is surpassed.

In the tallgrass prairies of the United States, the regal fritillary (Speyeria idalia) often is considered a reliable indicator of high quality remnant habitat. Purple milkweed (Asclepias purpurascens) is considered an indicator of high quality oak savanna habitat at the edge of prairie. Indicator and other surrogate species often are regarded as inescapable necessities in conservation, because limited budgets and the myriad pieces of an ecosystem render comprehensive monitoring impossible. Regardless of whether or not surrogate species are necessary, do they really work?

1. Telomeres are long repetitive noncoding sequences of DNA located at the ends of chromosomes. Recently, the study of telomere dynamics has been increasingly used to investigate ecological questions. However, little is currently known about the relationships that link environmental conditions, telomere dynamics and fitness in wild vertebrates.
2. Using a small migratory bird (American redstart, Setophaga ruticilla), we investigated how telomere dynamics can be affected by non-breeding habitat quality and to what extent telomere length can predict the return rate of males.
3. We show that telomeres shorten in most individuals over a 1-year period and, importantly, that telomeres of individuals wintering in a low-quality habitat shorten more than those of individuals wintering in a high-quality habitat.
4. In addition, we found that longer telomeres are associated with a higher return rate than shorter telomeres, although the relationship between return rate and telomere length did not depend on habitat quality.
5. Our study suggests that telomere dynamics are affected by environmental conditions and are related to indices of fitness in a migratory bird species.

Do you know the difference between the Miscanthus species? One species of Miscanthus is now being evaluated for its bioenergy potential. However, two other species of Miscanthus are becoming invasive in the United States. Due to the invasive risk, this resource will help you learn to identify each species.

The primary objective of this project was to estimate the nitrate reduction that could be achieved using restored wetlands as nitrogen sinks in tile-drained regions of the upper Mississippi River (UMR) and Ohio River basins. This report provides an assessment of nitrate concentrations and loads across the UMR and Ohio River basins and the mass reduction of nitrate loading that could be achieved using wetlands to intercept nonpoint source nitrate loads. Nitrate concentration and stream discharge data were used to calculate stream nitrate loading and annual flow-weighted average (FWA) nitrate concentrations and to develop a model of FWA nitrate concentration based on land use. Land use accounts for 90% of the variation among stations in long term FWA nitrate concentrations and was used to estimate FWA nitrate concentrations for a 100 ha grid across the UMR and Ohio River basins. Annual water yield for grid cells was estimated by interpolating over selected USGS monitoring station water yields across the UMR and Ohio River basins. For 1990 to 1999, mass nitrate export from each grid area was estimated as the product of the FWA nitrate concentration, water yield and grid area. To estimate potential nitrate removal by wetlands across the same grid area, mass balance simulations were used to estimate percent nitrate reduction for hypothetical wetland sites distributed across the UMR and Ohio River basins. Nitrate reduction was estimated using a temperature dependent, area-based, firstorder model. Model inputs included local temperature from the National Climatic Data Center and water yield estimated from USGS stream flow data. Results were used to develop a nonlinear model for percent nitrate removal as a function of hydraulic loading rate (HLR) and temperature. Mass nitrate removal for potential wetland restorations distributed across the UMR and Ohio River basin was estimated based on the expected mass load and the predicted percent removal. Similar functions explained most of the variability in per cent and mass removal reported for field scale experimental wetlands in the UMR and Ohio River basins. Results suggest that a 30% reduction in nitrate load from the UMR and Ohio River basins could be achieved using 210,000-450,000 ha of wetlands targeted on the highest nitrate contributing areas.

One of the greatest feats of avian migration is the non-stop crossing of extensive areas of inhospitable habitat such as deserts and seas. Differences in spring and autumn migration routes have been reported in species that cross such barriers, and are thought to have evolved in response to seasonal variation in prevailing wind direction. We tested the hypothesis that migration routes vary seasonally with respect to the Gulf of Mexico in the tree swallow Tachycineta bicolor using solar geolocators attached and retrieved at 4 breeding sites in central North America. We found that 100 % of birds (n = 10) made a trans-Gulf flight of >850 km from Louisiana south to their wintering grounds in the Yucatan Peninsula in 12–36 hours, achieving minimum ground speeds as high as 32 m/s. Although most days during autumn migration were characterized by unfavorable headwinds blowing to the northwest, migration over the Gulf mostly occurred on days with strong winds blowing to the south. In contrast, in 8 of 9 (88 %) birds on spring migration returned from the wintering grounds towards Louisiana following a clockwise loop pat tern flying over land to the west around the Gulf. During this spring period there were few days with prevailing winds from the south to assist northward migration. Results suggest that, despite being up to three times further (ca. 2,700 km), a coastal cir- cum-Gulf spring migration represents the less risky route when wind conditions are not favorable. These findings also help to re solve a long-standing dispute in the literature concerning migration patterns between the US Gulf coast and Mexico, and provide insight into the factors shaping migration strategies of small songbirds migrating across large bodies of water.

Employing a unique and rich data set of water quality attributes in conjunction with detailed household characteristics and trip information, we develop a mixed logit model of recreational lake usage and undertake thorough model specification and fitting procedures to identify the best set of explanatory variables, and their functional form for the estimated model. Our empirical analysis shows that individuals are responsive to the full set of water quality measures used by biologists to identify the impaired status of lakes. Thus, changes in these quality measures are not simply a scientific exercise, but they also translate into changes in the recreational usage patterns and well-being of individual households. Willingness-to-pay (WTP) estimates are reported based on improvements in these physical measures.