IBIS | Volume 157 | Issue 1 | January 2015
The January issue of Ibis contains 12 full papers, including one review paper, 7 Short Communications, book reviews and reports from the BOUâ€™s Records Committee and Taxonomic Sub-committee.
A review of the impacts of corvids on bird productivity and abundance | Christine Madden, Beatriz Arroyo & Arjun Amar
Our Review article in this issue is an important assessment of the impacts of corvids (crows and magpies) on other groups of birds. This is an important and potentially controversial contribution, as corvids are often blamed for declining populations of a number of other species, including species of commercial importance, and their numbers are often controlled as a result. In their review, Christine Madden, Beatriz Arroyo and Arjun Amar undertake a meta-analysis of published work, including both correlative and experimental removal studies, dividing their data into studies that assessed the impacts of corvids on productivity of other species and those that examined their impacts on population size. They find that in the majority of cases, there was no evidence for an effect of corvid predation on either measure, though where an effect was found, it tended to be at the level of productivity and not population level. Importantly, experimental studies that removed only corvids were significantly less likely to have a positive impact than those removing corvids together with other predators, suggesting that the impacts of corvids are small compared to other predator groups. The authors conclude that in the majority of cases, though by no means all, corvid removal is unlikely to be a cost effective way of increasing the productivity or populations of other birds.
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Low incubation investment in the burrow-nesting Crab Plover Dromas ardeola permits extended foraging on a tidal food resource | Giuseppe De Marchi, et al.
The Crab Plover Dromas ardeola is a remarkable member of the shorebird family. Uniquely in the group, it nests colonially in burrows. Giuseppe De Marchi of the University of Pavia and his colleagues investigate the consequences of this habit on the parentsâ€™ behaviour during nesting at a colony in Eritrea. Using GPS trackers, they find that during incubation, parents forage up to 26km from the nest and may stay away on foraging trips for up to two days, a pattern more reminiscent of seabirds foraging for their chicks than a wader. However, this did not indicate that birds struggle to find food, since they also spent plenty of time in the breeding colony not feeding, but mostly outside the nest. The authors conclude that the favourable thermal properties of the nest promote passive incubation, allowing parents to forage widely, so reducing competition with other members of the dense colony, and to spend a lot of time outside the nest even when in the colony, making the incubation period safer for the parents.
Assessing the short-term effects of capture, handling and tagging of sandgrouse | FabiÃ¡n Casas, et al.
Fitting tracking devices to birds is increasingly used to answer a wide range of questions in ecology and conservation, but the impacts of these devices on the birds is rarely assessed. In this issue, FabiÃ¡n Casas of the Spanish EstaciÃ³n Experimental de Zonas Ãridas and his colleagues assess the effects on post-tagging survival on two species of sandgrouse (Pterocildae). Although they found no impacts on survival in one species, in the other species they recorded significantly elevated mortality in the two weeks after the tags were fitted. Moreover, the authors found a significant effect of both tag weight and handling time; mortality was higher with heavier tags and longer handling time. The authors conclude that tags should not exceed 3% of body weight and that handling time should not exceed 20 minutes if the birds are not to suffer from the process.
A Plains-wanderer (Pedionomidae) that did not wander plains: a new species from the Oligocene of South Australia | Vanesa Pietri, et al.
Another remarkable species is Australiaâ€™s Plains-wanderer Pedionomus torquatus, an enigmatic quail-like bird that is the only living member of its family. Its closest relatives are thought to be the seedsnipes (Thinocoridae) of South America, but the ancestral roots of the two families are unknown. In this issue, Vanesa De Pietri and colleagues at Flinders University in Australia describe a new genus and species of plains-wanderer from a fossil dating from the Oligocene. They suggest that Oligonomus milleri was a woodland species, and that the extant speciesâ€™ distribution in open grassland is a derived characteristic, perhaps driven by the spread of grasslands across Australia during the Late Miocene/Pliocene. The age of the fossil suggests a Gondwanan origin for the ancestors of the plains-wanderers and the seedsnipe.
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