Male great bowerbirds create forced perspective illusions with consistently different individual quality

Males often produce elaborate displays that increase their attractiveness to females, and some species extend their displays to include structures or objects that are not part of their body. Such "extended phenotypes" may communicate information that cannot be transmitted by bodily signals or may provide a more reliable signal than bodily signals. However, it is unclear whether these signals are individually distinct and whether they are consistent over long periods of time. Male bowerbirds construct and decorate bowers that function in mate choice. Bower display courts constructed by male great bowerbirds (Ptilonorhynchus nuchalis) induce a visual illusion known as forced perspective for the female viewing the male's display over the court, and the quality of illusion is associated with mating success. We improved the quality of the forced perspective to determine whether males maintained it at the new higher level, decreased the perspective quality back to its original value, or allowed it to decay at random over time. We found that the original perspective quality was actively recovered to individual original values within 3 d.We measured forced perspective over the course of one breeding season and compared the forced perspective of individual males between two successive breeding seasons. We found that differences in the quality of visual illusion among males were consistent within and between two breeding seasons. This suggests that forced perspective is actively and strongly maintained at a different level by each individual male.

Lost at sea: genetic, oceanographic and meteorological evidence for storm-forced dispersal

For many species, there is broad-scale dispersal of juvenile stages and/or long-distance migration of individuals and hence the processes that drive these various wide-ranging movements have important life-history consequences. Sea turtles are one of these paradigmatic long-distance travellers, with hatchlings thought to be dispersed by ocean currents and adults often shuttling between distant breeding and foraging grounds. Here, we use multi-disciplinary oceanographic, atmospheric and genetic mixed stock analyses to show that juvenile turtles are encountered ‘downstream’ at sites predicted by currents. However, in some cases, unusual occurrences of juveniles are more readily explained by storm events and we show that juvenile turtles may be displaced thousands of kilometres from their expected dispersal based on prevailing ocean currents. As such, storms may be a route by which unexpected areas are encountered by juveniles which may in turn shape adult migrations. Increased stormy weather predicted under climate change scenarios suggests an increasing role of storms in dispersal of sea turtles and other marine groups with life-stages near the ocean surface.

'Everybody has settled in so well': How migrants make connections and build social capital in Geelong

Australian and Victorian Government policies encourage settlement in regional areas for international migrants, refugees and internal migrants. Migrants to regional areas are diverse in terms of their area or country of origin, skills and occupation, family status and other demographic characteristics. The regional cities to which they migrate are also varied in terms of their community resources, social and cultural capital. The objective shared by all of these cities is for migrants to engage successfully with their new communities. Just how this occurs is the subject of debate and a lack of clarity. This therefore calls for a sound, theoretically informed understanding of how employers and community groups (formal and informal) can effectively assist migrants to make social connections in regional cities, and practical strategies which respond to these insights. The well-established social determinants of health tell us that the more socially included, connected and stable workforce and their families are, the better will be their physical and mental health and wellbeing.

Testing the navigational abilities of ocean migrants: displacement experiments on green sea turtles (Chelonia mydas)

Like many animals migrating through the oceans, sea turtles face difficult navigational tasks when they have to reach distant, specific sites. The paradigmatic case of Brazilian green turtles (Chelonia mydas), which nest on the tiny Ascension Island in the middle of the Atlantic Ocean, has often been the subject of hypotheses concerning their navigational mechanisms. To investigate their nature, we displaced 18 females from Ascension and tracked them by satellite after release from eight different points in the ocean, 60–450 km away from the island. Four turtles moved to Brazil soon after the release, 4 moved in various directions before heading to Brazil, and 10 reached the island. All the successful trips, bar 1, were winding but ended with a final straight segment of variable length, as if the turtles were searching for a sensory contact with the island which they obtained at various distances. The approach to Ascension mostly occurred from the direction opposite to the trade wind, suggesting a navigational role of wind-borne information originating from the island.

Oceanic long-distance navigation : do experienced migrants use the earth's magnetic field?

Albatrosses and sea turtles are known to perform extremely long-distance journeys between disparate feeding areas and breeding sites located on small, isolated, oceanic islands or at specific coastal sites. These oceanic journeys, performed mainly over or through apparently featureless mediums, indicate impressive navigational abilities, and the sensory mechanisms used are still largely unknown. This research used three different approaches to investigate whether bi-coordinate navigation based on magnetic field gradients is likely to explain the navigational performance of wandering albatrosses in the South Atlantic and Indian Oceans and of green turtles breeding on Ascension Island in the South Atlantic Ocean. The possibility that magnetic field parameters can potentially be used in a bi-coordinate magnetic map by wandering albatrosses in their foraging area was investigated by analysing satellite telemetry data published in the literature. The possibilities for using bi-coordinate magnetic navigation varied widely between different areas of the Southern Oceans, indicating that a common mechanism, based on a bi-coordinate geomagnetic map alone, was unlikely for navigation in these areas. In the second approach, satellite telemetry was used to investigate whether Ascension Island green turtles use magnetic information for navigation during migration from their breeding island to foraging areas in Brazilian coastal waters. Disturbing magnets were applied to the heads and carapaces of the turtles, but these appeared to have little effect on their ability to navigate. The only possible effect observed was that some of the turtles with magnets attached were heading for foraging areas slightly south of the control turtles along the Brazilian coast. In the third approach, breeding female green turtles were deliberately displaced in the waters around Ascension Island to investigate which cues these turtles might use to locate and return to the island; the results suggested that cues transported by wind might be involved in the final stages of navigation.

Access to social insurance in urban China: a comparative study of rural-urban and urban-urban migrants in Beijing

 Since 1958 the hukou (household registration) system has assigned Chinese citizens either a rural or urban status. Some studies argue that the rural-to-urban migrants in China who do not have urban hukou are not entitled to urban social insurance schemes, due to institutional discrimination, which applies differing treatment to urban and rural hukou (chengxiang fenge). Although rural-urban migrants participate less in the social insurance system than their counterparts with urban hukou, a closer examination of recent policy developments shows that migrants actually do have the legal right to access the system. This implies that discrimination between rural and urban workers has been declining, and distinctions based on household registration status are less able to explain China's current urban transition. This paper provides a new way of examining Chinese migrants' social insurance participation, by adopting a framework that includes both rural-to-urban migrants and urban-to-urban migrants, which are an important, but less studied, migrant group. Among our key findings are that urban migrants are more likely to sign a labour contract than rural migrants; urban migrants have higher participation rates in social insurance than rural migrants; having a labour contract has a greater impact than hukou status in determining whether Beijing's floating population accesses social insurance; and urban migrants who have signed a labour contract have higher participation rates in social insurance than either rural migrants or urban migrants without a labour contract. © 2013 Elsevier Ltd.