Animal migration

Genetic data are commonly used to estimate connectivity between putative populations, but translating them to demographic dispersal rates is complicated. Theoretical equations that infer a migration rate based on the genetic estimator , such as Wright's equation, ≈ 1/(4 + 1), make assumptions that do not apply to most real populations. How complexities inherent to real populations affect migration was exemplified by Atlantic cod in the North Sea and Skagerrak and was examined within an age-structured model that incorporated genetic markers. Migration was determined under various scenarios by varying the number of simulated migrants until the mean simulated level of genetic differentiation matched a fixed level of genetic differentiation equal to empirical estimates. Parameters that decreased the / ratio (where is the effective and is the total population size), such as high fishing mortality and high fishing gear selectivity, increased the number of migrants required to achieve ...

Abstract:  Although there are many indicators of endangerment (i.e., whether populations or species meet criteria that justify conservation action), their reliability has rarely been tested. Such indicators may fail to identify that a population or species meets criteria for conservation action (false negative) or may incorrectly show that such criteria have been met (false positive). To quantify the rate of both types of error for 20 commonly used indicators of declining abundance (threat indicators), we used receiver operating characteristic curves derived from historical (1938–2007) data for 18 sockeye salmon (Oncorhynchus nerka) populations in the Fraser River, British Columbia, Canada. We retrospectively determined each population's yearly status (reflected by change in abundance over time) on the basis of each indicator. We then compared that population's status in a given year with the status in subsequent years (determined by the magnitude of decline in abundance across those years). For each sockeye population, we calculated how often each indicator of past status matched subsequent status. No single threat indicator provided error-free estimates of status, but indicators that reflected the extent (i.e., magnitude) of past decline in abundance (through comparison of current abundance with some historical baseline abundance) tended to better reflect status in subsequent years than the rate of decline over the previous 3 generations (a widely used indicator). We recommend that when possible, the reliability of various threat indicators be evaluated with empirical analyses before such indicators are used to determine the need for conservation action. These indicators should include estimates from the entire data set to take into account a historical baseline.Resumen:  Aunque existen muchos indicadores de riesgo (i.e., sí las poblaciones o especies cumplen con criterios para justificar acciones de conservación), su confiabilidad ha sido probada pocas veces. Dichos indicadores pueden fallar al identificar que una población o especie cumple con criterios para acciones de conservación (negativo falso) o pueden mostrar incorrectamente que tales criterios se han cumplido (positivo falso). Para cuantificar la tasa de ambos tipos de error para 20 indicadores de declinación de abundancia (indicadores de amenaza) utilizados comúnmente, utilizamos curvas de características de operación de receptores derivadas de datos históricos (1937–2008) de 18 poblaciones de salmón (Oncorhynchus nerka) en el Río Fraser, Columbia Británica, Canadá. Retrospectivamente determinamos el estatus anual de cada población (reflejado en cambios en la abundancia en el tiempo) con base en cada indicador. Posteriormente comparamos el estatus de la población en un año determinado con el estatus de años subsecuentes (determinado por la magnitud de la declinación en abundancia en esos años). Para cada población de salmón, calculamos la frecuencia en que cada indicador de estatus pasado era igual al estatus subsecuente. Ningún indicador de amenaza proporcionó estimaciones de estatus libres de error, pero los indicadores que reflejaron la extensión (i.e., magnitud) de la declinación en abundancia pasada (mediante comparación de la abundancia actual con la abundancia histórica de referencia) tendieron a reflejar de mejor manera el estatus en años anteriores que la tasa de declinación en las 3 generaciones previas (un indicador ampliamente utilizado). Recomendamos que, cuando sea posible, se evalúe la confiabilidad de varios indicadores de amenaza con análisis empíricos antes de que esos indicadores sean utilizados para determinar la necesidad de acciones de conservación. Estos indicadores deben incluir estimaciones a partir del total de datos para considerar una referencia histórica.Resumen:  Aunque existen muchos indicadores de riesgo (i.e., sí las poblaciones o especies cumplen con criterios para justificar acciones de conservación), su confiabilidad ha sido probada pocas veces. Dichos indicadores pueden fallar al identificar que una población o especie cumple con criterios para acciones de conservación (negativo falso) o pueden mostrar incorrectamente que tales criterios se han cumplido (positivo falso). Para cuantificar la tasa de ambos tipos de error para 20 indicadores de declinación de abundancia (indicadores de amenaza) utilizados comúnmente, utilizamos curvas de características de operación de receptores derivadas de datos históricos (1937–2008) de 18 poblaciones de salmón (Oncorhynchus nerka) en el Río Fraser, Columbia Británica, Canadá. Retrospectivamente determinamos el estatus anual de cada población (reflejado en cambios en la abundancia en el tiempo) con base en cada indicador. Posteriormente comparamos el estatus de la población en un año determinado con el estatus de años subsecuentes (determinado por la magnitud de la declinación en abundancia en esos años). Para cada población de salmón, calculamos la frecuencia en que cada indicador de estatus pasado era igual al estatus subsecuente. Ningún indicador de amenaza proporcionó estimaciones de estatus libres de error, pero los indicadores que reflejaron la extensión (i.e., magnitud) de la declinación en abundancia pasada (mediante comparación de la abundancia actual con la abundancia histórica de referencia) tendieron a reflejar de mejor manera el estatus en años anteriores que la tasa de declinación en las 3 generaciones previas (un indicador ampliamente utilizado). Recomendamos que, cuando sea posible, se evalúe la confiabilidad de varios indicadores de amenaza con análisis empíricos antes de que esos indicadores sean utilizados para determinar la necesidad de acciones de conservación. Estos indicadores deben incluir estimaciones a partir del total de datos para considerar una referencia histórica.

Climate change is taking place more rapidly and severely in the Arctic than anywhere on the globe, exposing Arctic vertebrates to a host of impacts. Changes in the cryosphere dominate the physical changes that already affect these animals, but increasing air temperatures, changes in precipitation, and ocean acidification will also affect Arctic ecosystems in the future. Adaptation via natural selection is problematic in such a rapidly changing environment. Adjustment via phenotypic plasticity is therefore likely to dominate Arctic vertebrate responses in the short term, and many such adjustments have already been documented. Changes in phenology and range will occur for most species but will only partly mitigate climate change impacts, which are particularly difficult to forecast due to the many interactions within and between trophic levels. Even though Arctic species richness is increasing via immigration from the South, many Arctic vertebrates are expected to become increasingly ...

Linear infrastructure such as roads, highways, power lines and gas lines are omnipresent features of human activity and are rapidly expanding in the tropics. Tropical species are especially vulnerable to such infrastructure because they include many ecological specialists that avoid even narrow (<30-m wide) clearings and forest edges, as well as other species that are susceptible to road kill, predation or hunting by humans near roads. In addition, roads have a major role in opening up forested tropical regions to destructive colonization and exploitation. Here, we synthesize existing research on the impacts of roads and other linear clearings on tropical rainforests, and assert that such impacts are often qualitatively and quantitatively different in tropical forests than in other ecosystems. We also highlight practical measures to reduce the negative impacts of roads and other linear infrastructure on tropical species.

Synopsis Evidence for climate-driven phenological changes is rapidly increasing at all trophic levels. Our current poor knowledge of the detailed control of bird migration from the level of genes and hormonal control to direct physiological and behavioral responses hampers our ability to understand and predict consequences of climatic change for migratory birds. In order to better understand migration phenology and adaptation in environmental changes, we here assess the scale at which weather affects timing of spring migration in passerine birds. We use three commonly used proxies of spring-time climatic conditions: (1) vegetation &apos;&apos;greenness&apos;&apos; (NDVI) in Europe, (2) local spring temperatures in northern Europe, and (3) the North Atlantic Oscillation Index (NAO) as predictors of the phenology of avian migration as well as the strength of their effect on different subsets of populations and the dependence of correlations on species-specific migratory strategy. We a...

The literature on fisheries co-management is almost silent on the issue of the movement of fisherfolk within fisheries, although such movement must have implications for the effectiveness of co-management. The introduction of co-management often involves the formation of new structures that should enable the participation of key stakeholder groups in decision-making and management, but such participation is challenging for migrating fishers. The article reports on a study on Lake Victoria, East Africa, which investigated the extent of movement around the lake and the implications of movement for how fishers participate and are represented in co-management, and the implications of the extent and nature of movement for co-management structures and processes. The analysis draws on the concept of space from the literature on participation in development and on a framework of representation in fisheries co-management in addressing these questions. The created space is on an &#39;invited&...

Large numbers of bats are killed by collisions with wind turbines, and there is at present no direct method of reducing or preventing this mortality. We therefore determine whether the electromagnetic radiation associated with radar installations can elicit an aversive behavioural response in foraging bats. Four civil air traffic control (ATC) radar stations, three military ATC radars and three weather radars were selected, each surrounded by heterogeneous habitat. Three sampling points matched for habitat type and structure, dominant vegetation species, altitude and surrounding land class were located at increasing distances from each station. A portable electromagnetic field meter measured the field strength of the radar at three distances from the source: in close proximity (&lt;200 m) with a high electromagnetic field (EMF) strength &gt;2 volts/metre, an intermediate point within line of sight of the radar (200-400 m) and with an EMF strength &lt;2 v/m, and a control site out of...

Strictly Protected Areas and riparian forests in Brazil are rarely large enough or connected enough to maintain viable populations of carnivores and animal movement over time, but these characteristics are fundamental for species conservation as they prevent the extinction of isolated animal populations. Therefore, the need to maintain connectivity for these species in human-dominated Atlantic landscapes is critical. In this study, we evaluated the landscape connectivity for large carnivores (cougar and jaguar) among the Strictly Protected Areas in the Atlantic Forest, evaluated the efficiency of the Mosaics of Protected Areas linked to land uses in promoting landscape connectivity, identified the critical habitat connections, and predicted the landscape connectivity status under the implementation of legislation for protecting riparian forests. The method was based on expert opinion translated into land use and land cover maps. The results show that the Protected Areas are still co...

If there were geese anywhere in the universe besides earth, we should probably expect to find them in the constellation Vulpecula. Vulpecula the Fox was contrived by Johannes Hevelius, the famous Polish astronomer who was based in Gdansk in the seventeenth century. Hevelius originally named this constellation Vulpecula & Anser, or the Fox & Goose. It’s no longer possible, however, to take a gander at the Goose. The Goose is long gone, ingested by the Fox in whose jaws Hevelius mapped its neck. Vulpecula is located right next to Cygnus the Swan, and for this 2005 Boeing Science Writing Contest article, Bernie Taylor has allowed those extraterrestrial geese to migrate to an imagined planet in the Swan, Cygnus 3. Bernie Taylor is a quantitatively-minded naturalist living in Oregon’s Willamette Valley. His 2004 book, Biological Time, examines the rhythms that regulate the lives of animals and plants and documents as well as ancient and indigenous knowledge of these natural cycles.
Some of these biological rhythms are modulated by celestial phenomena, and so Mr. Taylor asks whether different astronomical circumstances would alter the behavior of geese on another world or even eliminate the possibility of their existence. His imaginary planet in some ways parallels the earth. It is the third planet from its sun, a solar-like star in Cygnus. Notwithstanding the similarity of Cygnus 3 to earth, looking for geese on that planet could be a wild-goose chase.
The ancients imagined the constellation Cygnus as a swan in flight, headed south. They linked its seasonal departure from the night sky to the autumn migration of water fowl. Our failure to find any geese on Cygnus 3 wouldn't necessarily mean they don’t exist. They could, after all, have just gone south on us. What’s good for the Goose is sauce for the Swan. —E.C. Krupp, Director of the Griffith Observatory

Global climate change is a major threat to biodiversity. Large-scale analyses have generally focused on the impacts of climate change on the geographic ranges of species and on phenology, the timing of ecological phenomena. We used long-term monitoring of the abundance of breeding birds across Europe and the United States to produce, for both regions, composite population indices for two groups of species: those for which climate suitability has been either improving or declining since 1980. The ratio of these composite indices, the climate impact indicator (CII), reflects the divergent fates of species favored or disadvantaged by climate change. The trend in CII is positive and similar in the two regions. On both continents, interspecific and spatial variation in population abundance trends are well predicted by climate suitability trends.

Tracking small migrant organisms worldwide has been hampered by technological and recovery limitations and sampling bias inherent in exogenous markers. Naturally occurring stable isotopes of H (δ(2)H) in feathers provide an alternative intrinsic marker of animal origin due to the predictable spatial linkage to underlying hydrologically driven flow of H isotopes into foodwebs. This approach can assess the likelihood that a migrant animal originated from a given location(s) within a continent but requires a robust algorithm linking H isotopes in tissues of interest to an appropriate hydrological isotopic spatio-temporal pattern, such as weighted-annual rainfall. However, a number of factors contribute to or alter expected isotopic patterns in animals. We present results of an extensive investigation into taxonomic and environmental factors influencing feather δ(2)H patterns across North America.

Despite widespread concern about declines in pollination services, little is known about the patterns of change in most pollinator assemblages. By studying bee and hoverfly assemblages in Britain and the Netherlands, we found evidence of declines (pre- versus post-1980) in local bee diversity in both countries; however, divergent trends were observed in hoverflies. Depending on the assemblage and location, pollinator declines were most frequent in habitat and flower specialists, in univoltine species, and/or in nonmigrants. In conjunction with this evidence, outcrossing plant species that are reliant on the declining pollinators have themselves declined relative to other plant species. Taken together, these findings strongly suggest a causal connection between local extinctions of functionally linked plant and pollinator species.

People have had the moon’s number for a very long time. We figure the moon’s phases were counted by calendar priests in ancient Egypt and Mesopotamia at least 5000 years ago, and the unwritten record of prehistoric megaliths and symbolic carvings on monumental stones
has prompted some to speculate the builders of Stonehenge in southern England and Newgrange in Ireland also numbered the moon’s days. In fact, the late Alexander Marshack identifi ed “time-factored
notations” from the upper paleolithic in fragments of antler and bone. In The Roots of Civilization (1972), he argued these sequences of marks indicate lunar talllies. In 1982, American anthropologist W. Breen
Murray reported a large petroglyph panel at Presa de la Mula, in northeast Mexico, and interpreted its 24-cell grid of 207 “tally” marks as a count of seven cycles of the moon. The age of the carvings is
unknown, but through style they are associated with nomadic Archaic hunters and could be hundreds, if not thousands, of years old. Murray also analyzed tine counts of antler petroglyphs in the same desert
basins of northern Mexico and found they routinely exceed the number encountered on real antlers. Lunar numbers—7, 14, 15, 28—are common, but Murray speculated the month counts could reference
more than the moon and have something to do with biological cycles of the game.

In this issue, naturalist Bernie Taylor returns to the Griffiffith  Observer and explores detailed connections between lunar counts among traditional peoples and animal behavior. He last appeared in the August, 2006, issue with his 2005 Boeing writing contest article “Are There Geese on Cygnus 3?” He has written two books and hundreds of articles. In Biological Time (2004), he examined the relationship between the rhythms of plants and animals and the cyclical performances of the sun and moon. His work has generated high interest at biological conferences. Fish and game biologists are using his hypotheses to study and manage natural resources. Mr. Taylor has also spotlighted and analyzed archaeological evidence that suggests our ancient and prehistoric ancestors also understood the world and managed their access to its resources in terms of time measured and marked by the sun and the moon.