An experimental evaluation of the effects of geolocator design and attachment method on between-year survival on Whinchats Saxicola rubetra

Data from location logging tags have revolutionised our understanding of migration ecology, but methods of tagging that do not compromise survival need to be identified. We compared resighting rates for 156 geolocator-tagged and 316 colour ringed-only whinchats on their African wintering grounds after migration to and from eastern Europe in two separate years. We experimentally varied both light stalk length (0, 5 and 10 mm) and harness material (elastic or non-elastic nylon braid tied on, leg-loop ‘Rappole’ harnesses) in the second year using a reasonably balanced design (all tags in the first year used an elastic harness and 10 mm light stalk). Tags weighed 0.63 g (0.01 SE), representing 4.1% of average body mass. There was no overall significant reduction in between-year resighting rate (our proxy for survival) comparing tagged and untagged birds in either year. When comparing within tagged birds, however, using a tied harness significantly reduced resighting rate by 53% on average compared to using an elastic harness (in all models), but stalk length effects were not statistically significant in any model considered. There was no strong evidence that the fit (relative tightness) or added tag mass affected survival, although tied tags were fitted more tightly later in the study, and birds fitted with tied tags later may have had lower survival. Overall, on a precautionary principle, deploying tags with non-elastic tied harnesses should be avoided because the necessary fit, so as not to reduce survival, is time-consuming to achieve and does not necessarily improve with experience. Geolocator tags of the recommended percentage of body mass fitted with elastic leg-loop harnesses and with short light stalks can be used without survival effects in small long-distance migrant birds.PostprintPeer reviewe

Spring migration strategies of Whinchat Saxicola rubetra when successfully crossing potential barriers of the Sahara and the Mediterranean Sea

This work was supported by Chris Goodwin, A.P. Leventis Conservation Foundation, AP Leventis Ornithological Research Institute, the British Ornithologists’ Union and the Linnean Society.The flexibility for migrant land birds to be able to travel long distances rapidly without stop-overs, and thus to cross wide inhospitable areas such as deserts and oceans, is likely to be a major determinant of their survival during migration. We measured variation in flight distance, speed, and duration of major stop-overs (more than two days), using geolocator tracks of 35 Whinchats Saxicola rubetra that migrated successfully from central Nigeria to Eastern Europe in spring, and how these measures changed, or depended on age, when crossing the barriers of the Sahara or the Mediterranean Sea. Thirty-one percent of Whinchats crossed at least the Sahara and the Mediterranean before a major stop-over; 17% travelled over 4,751 km on average without any major stop-overs. Flight distance and speed during, and duration of major stop-overs after, crossing the Mediterranean Sea were indistinguishable from migration over Continental Europe. Speed during a migration leg was lowest crossing Continental Europe and fastest, with longer duration major stop-overs afterwards, when crossing the Sahara, but there was much individual variation, and start date of migration was also a good predictor of stop-over duration. As the distance travelled during a leg increased, so major stop-over duration afterwards increased (1 day for every 1000km), but the speed of travel during the leg had no effect. There were no differences in any migration characteristics with age, other than an earlier start date for adult birds. The results suggest that adaptive shortening or even dropping of daily stop-overs may occur often, allowing rapid, long-distance migration at the cost of major stop-overs afterwards, but such behaviour is not restricted to or always found when crossing barriers, even for birds on their first spring migration. The results may highlight the importance of stop-over sites rather than barrier width as the likely key component to successful migration. Individual variation in spring migration may indicate that small passerine migrants like Whinchats may be resilient to future changes in the extent of barriers they encounter, although this may not be true of first autumn migrations or if stop-over sites are lost.PostprintPeer reviewe

Study of the footprints of short-term variation in XCO₂ observed by TCCON sites using NIES and FLEXPART atmospheric transport models

The Total Carbon Column Observing Network (TCCON) is a network of ground-based Fourier Transform Spectrometers (FTS) that record near-infrared (NIR) spectra of the Sun. From these spectra, accurate and precise observations of CO2 column-averaged dry-air mole fraction (denoted XCO2) are retrieved. TCCON FTS observations have previously been used to validate satellite estimations of XCO2; however, our knowledge of the short-term spatial and temporal variations in XCO2 surrounding the TCCON sites is limited. In this work, we use the National Institute for Environmental Studies (NIES) Eulerian three-dimensional transport model and the FLEXPART (FLEXible PARTicle) Lagrangian Particle Dispersion Model (LPDM) to determine the footprints of short-term variations in XCO2 observed by operational, past, future, and possible TCCON sites. We propose a footprint-based method for the colocation of satellite and TCCON XCO2 observations, and estimate the performance of the method using the NIES model and five GOSAT XCO2 product datasets. Comparison of the proposed approach with a standard geographic method shows higher number of colocation points and average bias reduction up to 0.15 ppm for a subset of 16 stations for the period from January 2010 to January 2014. Case studies of the Darwin and La Réunion sites reveal that when the footprint area is rather curved, non-uniform and significantly different from a geographical rectangular area, the differences between these approaches are more noticeable. This emphasizes that the colocation is sensitive to local meteorological conditions and flux distributions

Testiranje pokrivenog kamatnog pariteta: slučaj HRK/EUR

Cilj ovog rada je uspostaviti vezu između terminske premije/diskonta i kamatnog diferencijala koristeći model pokrivenog kamatnog pariteta (CIRP). Model je izgrađen na pretpostavkama visoke mobilnosti kapitala, savršene supstitucije valuta i odsutnosti transakcijskih troškova. Postojanje pokrivenog kamatnog pariteta testirano je na podacima tečaja eura i kune za Hrvatsku u 2010. godini. Rezultati su potvrdili skoro savršeno važenje pokrivenog kamatnog pariteta u kratkom roku koristeći referentne kamatnjake ZIBOR i EURIBOR kao i odgovarajuće vrijednosti spot i forward HRK/EUR tečaja odgovarajuće ročnosti od 1, 3, 6, 9 i 12 mjeseci. Ekonometrijski test je proveden kako bi se procijenio nagib linije pokrivenog kamatnog pariteta. Rezultati su pokazali kako je empirijska vrijednost nagiba linije kamatnog pariteta gotovo identična očekivanoj vrijednosti koristeći teorijski model pokrivenog kamatnog pariteta. Zbog relativno uske zone kamatnog pariteta kratkoročne mogućnosti arbitraže su minimizirane kao i vjerojatnost ostvarenja nerizičnog profita

Study of the footprints of short-term variation in XCO_2 observed by TCCON sites using NIES and FLEXPART atmospheric transport models

The Total Carbon Column Observing Network (TCCON) is a network of ground-based Fourier transform spectrometers (FTSs) that record near-infrared (NIR) spectra of the sun. From these spectra, accurate and precise observations of CO_2 column-averaged dry-air mole fractions (denoted XCO_2) are retrieved. TCCON FTS observations have previously been used to validate satellite estimations of XCO_2; however, our knowledge of the short-term spatial and temporal variations in XCO_2 surrounding the TCCON sites is limited. In this work, we use the National Institute for Environmental Studies (NIES) Eulerian three-dimensional transport model and the FLEXPART (FLEXible PARTicle dispersion model) Lagrangian particle dispersion model (LPDM) to determine the footprints of short-term variations in XCO_2 observed by operational, past, future and possible TCCON sites. We propose a footprint-based method for the collocation of satellite and TCCON XCO_2 observations and estimate the performance of the method using the NIES model and five GOSAT (Greenhouse Gases Observing Satellite) XCO_2 product data sets. Comparison of the proposed approach with a standard geographic method shows a higher number of collocation points and an average bias reduction up to 0.15 ppm for a subset of 16 stations for the period from January 2010 to January 2014. Case studies of the Darwin and Reunion Island sites reveal that when the footprint area is rather curved, non-uniform and significantly different from a geographical rectangular area, the differences between these approaches are more noticeable. This emphasises that the collocation is sensitive to local meteorological conditions and flux distributions

Tropospheric formaldehyde retrievals with GOME-2

Biogenic Volatile Organic Compounds (BVOCs) emitted by terrestrial ecosystems impact air quality and climate. The most important BVOC for global tropospheric composition is isoprene, whose annual global emissions (400-600 Tg C/year) account for ~50% of the total global BVOC budget. Tropical ecosystems are generally thought to be responsible for 70-90% of the global isoprene budget. Satellite observations of formaldehyde (CH[subscript 2]O), a high-yield, short lifetime product of isoprene oxidation, provide top-down constraints on surface isoprene emissions. Errors in retrieved satellite slant column densities (SCD - trace gas concentration along the instrument's line of sight) are typically in the region of 40% for scenes with little cloud and aerosol contamination. Error sources arise from instability in the differential optical absorption spectroscopy (DOAS) retrieval procedure, largely due to low signal to noise ratios frequently encountered with space-borne UV spectrometers, coupled to CH[subscript 2]O's faint absorption signal. The essential conversion of SCDs to vertical column densities (VCDs - vertical trace gas concentration extending from the Earth's surface), needed for application of retrieved CH[subscript 2]O values to geochemical modelling schemes, is a further significant contributor to product error (30-60%), being strongly influenced by aerosol, cloud and albedo inhomogeneities at sub-pixel level. A new global 5 year CH[subscript 2]O product (2007-2011) generated with global ozone monitoring experiment 2 (GOME-2) satellite radiance data is presented. SCDs for this are generated with optimised spectroscopic fit settings derived from an extensive sensitivity study of input retrieval parameters for the DOAS portion of the retrieval. SCDs are then converted to vertical column densities VCDs using air mass factors calculated with a significantly upgraded retrieval scheme, accounting for atmospheric radiative transfer due to viewing geometry, surface albedo and atmospheric scattering. New GOME-2 CH[subscript 2]O VCDs are then evaluated against GEOS-Chem modelled CH[subscript 2]O VCDs, and compared to a suite of associated environmental parameters

Light stalks increase the precision and accuracy of non-breeding locations calculated from geolocator tags : a field test from a long-distance migrant

This work was supported by the Chris Goodwin, A.P. Leventis Conservation Foundation, AP Leventis Ornithological Research Institute, the British Ornithologists’ Union and the Linnean Society.Capsule: There is a substantial gain in precision and accuracy of geolocator locations when using a light stalk. Aims: Light stalks or tubes increase the accuracy of geolocators when tracking migrant birds because they reduce potential shading of the light sensor by feathers but may increase detrimental tag effects. We aimed to determine how adding light stalks to geolocator tags increased accuracy and precision of locations. Methods: We quantified how precision and accuracy of geolocator locations was affected by comparing variation of sunrise and sunset times from tags with variable length light stalks (6 of 0 mm, 8 of 5 mm and 21 of 10 mm). Tags were fitted to Whinchats Saxicola rubetra in central Nigeria (the known location to compare accuracy), and variance in latitude and longitude of geolocator estimated locations were also compared across light stalk lengths during spring migration stationary locations, and at breeding sites in Eastern Europe, for both Geolight and FlightR methods. Results: Without a light stalk, the standard deviation of sunset and sunrise times increased by 50% and 100% respectively (i.e. less precise): confidence intervals for latitude were larger by about 4.3 degrees at non-breeding low latitudes and 1.8 degrees at stop-over latitudes, or confidence intervals for longitude were larger by 2.3 degrees, dependent on analysis method. Estimated sun elevation angles were significantly less accurate and so calculated non-breeding locations were significantly less accurate by about 8 degrees of latitude. Precision in sunrise, sunset times, latitude and longitude, was similar when using a 5mm or 10mm stalk. Conclusions: The results show a substantial gain in precision and accuracy of low latitude geolocator locations when using a light stalk that brings the sensor above covering feathers. There is no advantage from longer light stalk lengths than those necessary to just expose the light sensor above the feathers, at least for small passerines.PostprintPeer reviewe