Highlights from the latest issue
January 2016 | Vol. 158, issue 1
A packed January issue of IBIS contains 15 full papers and four Short Communications. Here are just four of the highlights.
Here are just four of the many highlights in this issue.
- Trade and habitat change virtually eliminate the Grey Parrot Psittacus erithacus from Ghana
Nathaniel N. D. Annorbah, Nigel J. Collar & Stuart J. Marsden
The Grey Parrot is one of the most heavily traded bird species on the planet, but the effects of poaching for the cage-bird trade and habitat loss on the species’ population have not so far been assessed. Nathaniel Annorbah and colleagues from Manchester Metropolitan Museum and BirdLife International undertook counts of the species across Ghana and revisited roost sites known from previous decades. Their findings suggest an extraordinary rate of population decline of 90-99% since 1992, due to trapping and the loss of large, commercially important trees. The authors conclude that this rate of loss is likely to apply throughout the range of this species and the recently split Timneh Parrot Psittacus timneh and that the two species’ conservation status urgently needs to be re-evaluated.
- Limitations and mechanisms influencing the migratory performance of soaring birds: a test of a density-dependent mechanism
Tricia A. Miller, Robert P. Brooks, Michael J. Lanzone, David Brandes, Jeff Cooper, Junior A. Tremblay, Jay Wilhelm, Adam Duerr & Todd E. Katzner
Migrating birds need to balance the costs of time, energy and safety in determining their optimal migration strategy, which may differ between age and sex classes. Tricia Miller of Pennsylvania State University and colleagues used GPS telemetry to study the migratory strategies of Golden Eagles in North America. In spring, adults left their wintering sites earlier than young birds and moved north more quickly, but adults moving the furthest distances appeared to take advantage of energy-conservation strategies such as a decreasing their compensation for wind drift. On southward migration in autumn, however, all age classes moved south at the same slow rate, but those leaving later had faster migration, suggesting some time limitation. At all times of year, adults had higher flight performance than young birds. The results suggest that age and seasonal variation in time and energy minimization strategies are not necessarily exclusive of one another.
- Classification success of six machine learning algorithms in radar
Isabel M. D. Rosa, Ana Teresa Marques, Gustavo Palminha, Hugo Costa, Miguel Mascarenhas, Carlos Fonseca & Joana Bernardino Wanless
Radar systems have been increasingly used to monitor birds, for example in risk assessments of wind farm developments. To take full advantage of the large datasets provided by radars, researchers have implemented machine learning (ML) techniques that automatically read and attempt to classify targets. Isabel Rosa of Bio3 in Portugal and Imperial College and colleagues assess how well six different ML algorithms perform in identifying targets as birds and how well the can classify birds to species. All the algorithms performed well at identifying targets as birds, but there was greater variation between methods in classifying targets to functional groups or species, only Random Forests having an accuracy above 80% in all classifications. The results inform the use of automated processing of the data produced by radar.
- High within-winter and annual survival rates in a declining Afro-Palaearctic migratory bird suggest that wintering conditions of not limit populations
Emma Blackburn & Will Cresswell
The declining populations of many Afro-Palaearctic migratory bird species are causing concern among conservationists but it is still unclear whether these declines are due to environmental changes on the European breeding grounds or in the African wintering grounds. Emma Blackburn and Will Cresswell of the University of St Andrews examine the within-winter survival rates of Whinchats Saxicola rubetra in West Africa. By close observation of colour-ringed birds, the authors conclude that within-winter survival is extremely high, and suggest that most mortality occurs along the migration routes or on the European breeding grounds. Together with previously published data on the availability of Whinchat habitat in West Africa, the results suggest that over-winter conditions are not likely to be the cause of recent declines in this species’ populations.
- Book reviews View