ALBERT

Description: New climate simulations using the HadCM3L model with a paleogeography of the Late Jurassic [155.5 Ma], and proxy-data corroborate that warm and wet tropical-like conditions reached as far north as the UK sector of the Jurassic Boreal Seaway [~35 o N]. This is associated with a northern hemisphere Jurassic Hadley cell and an intensified subtropical jet which both extend significantly polewards than in the modern (July-September). Deposition of the Kimmeridge Clay Formation [KCF] occurred in the shallow, storm-dominated, epeiric Boreal Seaway. High resolution paleo-environmental proxy data from the Kimmeridge Clay Formation [KCF; ~155–150 Ma], UK are used to test for the role of tropical atmospheric circulation on meter-scale heterogeneities in black shale deposition. Proxy and model data show that the most organic-rich section [ eudoxus to mid -hudlestoni zones] is characterised by a positive δ 13 C org excursion and up to 37 wt% total organic carbon [%TOC]. Orbital-modulation of organic carbon burial primarily in the long eccentricity power band combined with a clear positive correlation between %TOC carbonate-free and the kaolinite/illite ratio supports peak organic carbon burial under the influence of very humid climate conditions, similar to the modern tropics. This re-interpretation of large-scale climate relationships, supported by independent modelling and geological data, has profound implications for atmospheric circulation patterns and processes affecting marine productivity and organic carbon burial further north along the Boreal Seaway, including the Arctic.

Description: The TEX 86 proxy, based on the distribution of marine isoprenoidal glycerol dialkyl glycerol tetraether lipids (GDGTs), is increasingly used to reconstruct sea surface temperature (SST) during the Eocene epoch (56.0-33.9 Ma). Here we compile published TEX 86 records, critically re-evaluate them in light of new understandings in TEX 86 palaeothermometry and supplement them with new data in order to evaluate long term temperature trends in the Eocene. We investigate the effect of archaea other than marine Thaumarchaeota upon TEX 86 values using the branched-to-isoprenoid tetraether index (BIT), the abundance of GDGT-0 relative to crenarchaeol (%GDGT-0) and the Methane Index (MI). We also introduce a new ratio, %GDGT RS, which may help identify Red Sea-type GDGT distributions in the geological record. Using the offset between TEX 86 H and TEX 86 L (ΔH-L) and the ratio between GDGT-2 and GDGT-3 ([2]/[3]), we evaluate different TEX 86 calibrations and present the first integrated SST compilation for the Eocene (55 to 34 Ma). Although the available data are still sparse some geographic trends can now be resolved. In the high-latitudes (〉55 °), there was substantial cooling during the Eocene (~6 °C). Our compiled record also indicates tropical cooling of ~2.5°C during the same interval. Using an ensemble of climate model simulations that span the Eocene, our results indicate that only a small percentage (~10%) of the reconstructed temperature change can be ascribed to ocean gateway reorganisation or paleogeographic change. Collectively, this indicates that atmospheric carbon dioxide ( p CO 2 ) was the likely driver of surface water cooling during the descent towards the icehouse.

Description: Early Jurassic marine palaeotemperatures have been typically quantified by oxygen-isotope palaeothermometry of benthic and nektonic carbonate and phosphatic macrofossils. However, records of Early Jurassic sea-surface temperatures that can be directly compared with general circulation model simulations of past climates are currently unavailable. The TEX 86 sea-surface temperature proxy is based upon the relative abundance of glycerol dialkyl glycerol tetraethers preserved in organic-carbon-bearing sediments. This proxy has been used extensively on Cretaceous and Cenozoic materials and, in one study, Middle and Upper Jurassic sediments. Here TEX 86 is applied, for the first time, to Lower Jurassic (Sinemurian–Pliensbachian) sediments cored at Deep Sea Drilling Project Site 547 in the North Atlantic. The abundance of glycerol dialkyl glycerol tetraethers in these sediments is very low, despite biomarker and Rock-Eval data suggesting that thermal maturity is, generally, low. Sea-floor oxygenation and a high input of reworked terrestrially sourced organic matter may explain the low concentrations. For samples from which it was possible to quantify the relative abundance of glycerol dialkyl glycerol tetraethers, TEX 86 values range from 0.78 to 0.88, equating to sea-surface temperatures in excess of 〉28°C. These temperatures are broadly comparable with new general circulation model simulations of the Sinemurian and Pliensbachian stages and support the general view of a predominantly warm climate. The new proxy data suggest that, under favourable geological conditions, it is possible to extend the record of TEX 86 -based sea-surface temperatures back into the Early Jurassic. This article is protected by copyright. All rights reserved.

Description: Evaluation of the progress of management programs for invasive species is crucial for demonstrating impacts to stakeholders and strategic planning of resource allocation. Estimates of abundance before and after management activities can serve as a useful metric of population management programs. However, many methods of estimating population size are too labor intensive and costly to implement, posing restrictive levels of burden on operational programs. Removal models are a reliable method for estimating abundance before and after management using data from the removal activities exclusively, thus requiring no work in addition to management. We developed a Bayesian hierarchical model to estimate abundance from removal data accounting for varying levels of effort, and used simulations to assess the conditions under which reliable population estimates are obtained. We applied this model to estimate site-specific abundance of an invasive species, feral swine ( Sus scrofa ), using removal data from aerial gunning in 59 site/time-frame combinations (480-19,600 acres) throughout Oklahoma and Texas, U.S. Simulations showed that abundance estimates were generally accurate when effective removal rates (removal rate accounting for total effort) were above 0.40. However, when abundances were small (〈50) the effective removal rate needed to accurately estimates abundances was considerably higher (0.70). Based on our post-validation method 78% of our site/time frame estimates were accurate. To use this modeling framework it is important to have multiple removals (3+) within a time frame during which demographic changes are minimized (i.e., a closed population; ≤ 3 months for feral swine). Our results show that the probability of accurately estimating abundance from this model improves with increased sampling effort (8+ flight hours across the 3-month window is best) and increased removal rate. Based on the inverse relationship between inaccurate abundances and inaccurate removal rates, we suggest auxiliary information that could be collected and included in the model as covariates (e.g., habitat effects, differences between pilots) to improve accuracy of removal rates and hence abundance estimates. This article is protected by copyright. All rights reserved.

Description: In the face of global environmental change, the importance of protected areas in biological management and conservation is expected to grow. Birds have played an important role as biological indicators of the effectiveness of protected areas, but with little consideration given to where species occur outside the breeding season. We estimated weekly probability of occurrence for 308 bird species throughout the year within protected areas in the western contiguous USA using eBird occurrence data for the combined period 2004 to 2011. We classified species based on their annual patterns of occurrence on lands having intermediate conservation mandates (GAP status 2 and 3) administered by the Bureau of Land Management (BLM) and the United States Forest Service (USFS). We identified species having consistent annual association with one agency, and species whose associations across the annual cycle switched between agencies. BLM and USFS GAP status 2 and 3 lands contained low to moderate proportions of species occurrences, with proportions highest for species that occurred year-round or only during the summer. We identified two groups of species whose annual movements resulted in changes in stewardship responsibilities: (1) year-round species that occurred on USFS lands during the breeding season and BLM lands during the nonbreeding season; and (2) summer species that occurred on USFS lands during the breeding season and BLM lands during spring and autumn migration. Species that switched agencies had broad distributions, bred on high-elevation USFS lands, were not more likely to be identified as species of special management concern, and migrated short (year-round species) to long distances (summer species). Our findings suggest cooperative efforts that address the requirements of short-distance migratory species on GAP status 2 lands (n = 20 species) and GAP status 3 lands (n = 24) and long-distance migratory species on GAP status 2 lands (n = 9) would likely benefit their populations. Such efforts may prove especially relevant for species whose seasonal movements result in associations with different environments containing contrasting global change processes and management mandates. # doi:10.1890/14-0702.1

Description: Billions of birds migrate at night over North America each year. However, few studies have described the phenology of these movements, such as magnitudes, directions, and speeds, for more than one migration season and at regional scales. In this study, we characterize density, direction, and speed of nocturnally migrating birds using data from 13 weather surveillance radars in the autumns of 2010 and 2011 in the northeastern US. After screening radar data to remove precipitation, we applied a recently developed algorithm for characterizing velocity profiles with previously developed methods to document bird migration. Many hourly radar scans contained wind-borne “contamination,” and these scans also exhibited generally low overall reflectivities. Hourly scans dominated by birds showed nightly and seasonal patterns that differed markedly from those of low reflectivity scans. Bird migration occurred during many nights, but a smaller number of nights with large movements of birds defined regional nocturnal migration. Densities varied by date, time, and location but peaked in the second and third deciles of night during the autumn period when the most birds were migrating. Migration track (the direction to which birds moved) shifted within nights from south southwesterly to southwesterly during the seasonal migration peaks; this shift was not consistent with a similar shift in wind direction. Migration speeds varied within nights, although not closely with wind speed. Airspeeds increased during the night; groundspeeds were highest between the second and third deciles of night, when the greatest density of birds was migrating. Airspeeds and groundspeeds increased during the fall season, although groundspeeds fluctuated considerably with prevailing winds. Significant positive correlations characterized relationships among bird densities at southern coastal radar stations and northern inland radar stations. The quantitative descriptions of broad-scale nocturnal migration patterns presented here will be essential for biological and conservation applications. These descriptions help to define migration phenology in time and space, fill knowledge gaps in avian annual cycles, and are useful for monitoring long-term population trends of migrants. Furthermore, these descriptions will aid in assessing potential risks to migrants, particularly from structures with which birds collide and artificial lighting that disorients migrants. This article is protected by copyright. All rights reserved.

Description: Abstract Climate sensitivity is a key metric used to assess the magnitude of global warming given increased CO2 concentrations. The geological past can provide insights into climate sensitivity; however, on timescales of millions of years, factors other than CO2 can drive climate, including paleogeographic forcing and solar luminosity. Here, through an ensemble of climate model simulations covering the period 150‐35 million years ago, we show that climate sensitivity to CO2 doubling varies between ~3.5‐5.5°C through this time. These variations can be explained as a non‐linear response to solar luminosity, evolving surface albedo due to changes in ocean area, and changes in ocean circulation. The work shows that the modern climate sensitivity is relatively low in the context of the geological record, as a result of relatively weak feedbacks due to a relatively low CO2 baseline, and the presence of ice and relatively small ocean area in the modern continental configuration.

Description: Abstract The Earth system changed dramatically across the Eocene‐Oligocene Transition (EOT) on a variety of spatial and temporal scales. Understanding the many complex and interacting factors affecting the Earth's atmosphere and oceans at the EOT requires the combination of both data and modeling approaches and an understanding of the uncertainty in both of these elements. Here uncertainty in the Earth system response to various imposed forcings typical of changes at the EOT is assessed. By using an ensemble of simulations from the fully coupled general circulation model, HadCM3L, the uncertainty due to differences in the boundary conditions and insufficient model spin‐up is quantified. The surface temperature response in high‐latitude ocean regions, particularly where deep water formation occurs, is found to be highly sensitive to differences in boundary conditions (i.e., have the greatest magnitude of uncertainty), while low‐latitude oceans are the most insensitive to differences in boundary conditions (i.e., have the lowest magnitude of uncertainty). The length of spin‐up (or how far the model is from equilibrium) can have a significant effect on the response to some forcings and on the magnitude of uncertainty due to differences in boundary conditions. These findings are important to consider for future modeling work and for interpreting previous published simulations.

Description: We quantify the timing, intensity, and distribution of bird migration through one of the largest migration corridors in the Western Hemisphere, the Gulf of Mexico, by integrating citizen science (eBird) observations with weather surveillance radar data. We estimate that an average of 2.1 billion birds pass through this region each spring, with half of these individuals pass through the region in just 18 days, between April 19 and May 7. We did not detect an overall change in the annual numbers of migrants (2007–2015) or the annual timing of peak migration (1995–2015). Abstract Quantifying the timing and intensity of migratory movements is imperative for understanding impacts of changing landscapes and climates on migratory bird populations. Billions of birds migrate in the Western Hemisphere, but accurately estimating the population size of one migratory species, let alone hundreds, presents numerous obstacles. Here, we quantify the timing, intensity, and distribution of bird migration through one of the largest migration corridors in the Western Hemisphere, the Gulf of Mexico (the Gulf). We further assess whether there have been changes in migration timing or intensity through the Gulf. To achieve this, we integrate citizen science (eBird) observations with 21 years of weather surveillance radar data (1995–2015). We predicted no change in migration timing and a decline in migration intensity across the time series. We estimate that an average of 2.1 billion birds pass through this region each spring en route to Nearctic breeding grounds. Annually, half of these individuals pass through the region in just 18 days, between April 19 and May 7. The western region of the Gulf showed a mean rate of passage 5.4 times higher than the central and eastern regions. We did not detect an overall change in the annual numbers of migrants (2007–2015) or the annual timing of peak migration (1995–2015). However, we found that the earliest seasonal movements through the region occurred significantly earlier over time (1.6 days decade−1). Additionally, body mass and migration distance explained the magnitude of phenological changes, with the most rapid advances occurring with an assemblage of larger‐bodied shorter‐distance migrants. Our results provide baseline information that can be used to advance our understanding of the developing implications of climate change, urbanization, and energy development for migratory bird populations in North America.