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Banchory, United Kingdom

Natural Research

Banchory, United Kingdom
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Van Eeden R.,University of Cape Town | Whitfield D.P.,Natural Research | Botha A.,Birds of Prey Programme | Amar A.,University of Cape Town
PLoS ONE | Year: 2017

Understanding the ranging behaviours of species can be helpful in effective conservation planning. However, for many species that are rare, occur at low densities, or occupy challenging environments, this information is often lacking. The Martial Eagle (Polemaetus bellicosus) is a low density apex predator declining in both non-protected and protected areas in southern Africa, and little is known about its ranging behaviour. We use GPS tags fitted to Martial Eagles (n = 8) in Kruger National Park (KNP), South Africa to describe their ranging behaviour and habitat preference. This represents the first time that such movements have been quantified in adult Martial Eagles. Territorial eagles (n = 6) held home ranges averaging ca. 108 km2. Home range estimates were similar to expectations based on inter-nest distances, and these large home range sizes could constrain the carrying capacity of even the largest conservation areas. Two tagged individuals classed as adults on plumage apparently did not hold a territory, and accordingly ranged more widely (ca. 44,000 km2), and beyond KNP boundaries as floaters. Another two territorial individuals abandoned their territories and joined the 'floater' population, and so ranged widely after leaving their territories. These unexpected movements after territory abandonment could indicate underlying environmental degradation. Relatively high mortality of these wide-ranging 'floaters' due to anthropogenic causes (three of four) raises further concerns for the species' persistence. Habitat preference models suggested Martial Eagles used areas preferentially that were closer to rivers, had higher tree cover, and were classed as dense bush rather than open bush or grassland. These results can be used by conservation managers to help guide actions to preserve breeding Martial Eagles at an appropriate spatial scale. © 2017 van Eeden et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

News Article | March 1, 2017

The discovery of one of the oldest penguin fossils in the world reveals higher diversity of early penguins than previously assumed. Along the Waipara River in New Zealand's Canterbury region are sites rich in avian fossils, many of which were entombed in marine sand not long (relatively speaking) after the extinction of the dinosaurs. One of the more intriguing fossil finds there of late is that of a giant penguin discovered by ornithologist Dr. Gerald Mayr from the Senckenberg Society for Natural Research and a team of colleagues from New Zealand. The Waimanu penguin had a man-sized body length of 150 centimeters (5 feet) and dates back to the Paleocene era with an age of some 61 million years. It is among the oldest penguin fossils in the world. But what makes the Waimanu even more interesting is that the bones are significantly different from other penguin fossils from the same time period, revealing that the diversity of Paleocene penguins was higher than previously thought. The researchers conclude that because of this, the evolution of penguins started much earlier than assumed, likely already during the age of dinosaurs. "What sets this fossil apart are the obvious differences compared to the previously known penguin remains from this period of geological history," says Mayr. "The leg bones we examined show that during its lifetime, the newly described penguin was significantly larger than its already described relatives. Moreover, it belongs to a species that is more closely related to penguins from later time periods." The new (old) penguin lived some 61 million years ago; its impressive size makes it almost as large as the much younger Anthropornis nordenskjoeldi, the largest known fossil penguin, which lived around 45 to 33 million years ago. "This shows that penguins reached an enormous size quite early in their evolutionary history, around 60 million years ago," says Mayr. "The discoveries show that penguin diversity in the early Paleocene was clearly higher than we previously assumed," says Mayr. "In turn, this diversity indicates that the first representatives of penguins already arose during the age of dinosaurs, more than 65 million years ago." Below, an artist illustration of Waimanu on the beach. For more, see: A new fossil from the mid-Paleocene of New Zealand reveals an unexpected diversity of world's oldest penguins in The Science of Nature.

Liminana R.,Institute Investigacion en Recursos Cinegeticos IREC | Arroyo B.,Institute Investigacion en Recursos Cinegeticos IREC | Terraube J.,University of Turku | McGrady M.,Natural Research | Mougeot F.,CSIC - Estación Experimental De Zonas Áridas
ORYX | Year: 2015

Understanding the ecology of migratory birds during the non-breeding season is necessary for ensuring their conservation. Using satellite telemetry data we describe winter ranging behaviour and movements of pallid harriers Circus macrourus that bred in Kazakhstan. We developed an ecological niche model for the species in Africa, to identify the most suitable wintering areas for pallid harriers and the importance of habitat in determining the location of those areas. We also assessed how well represented suitable areas are in the network of protected areas. Individual harriers showed relatively high fidelity to wintering areas but with potential for interannual changes. The ecological niche model highlighted the importance of open habitats with natural vegetation. Most suitable areas for the species were located in eastern Africa. Suitable areas had a patchy distribution but were relatively well included in the network of protected areas. The preferential use of habitats with natural vegetation by wintering pallid harriers and the patchiness of the most suitable areas highlight the harrier's vulnerability to land-use changes and the associated loss of natural vegetation in Africa. Conservation of harriers could be enhanced by preserving natural grasslands within protected areas and improving habitat management in the human-influenced portions of the species' core wintering areas. Copyright © Fauna & Flora International 2014.

Vergara P.,University of Aberdeen | Martinez-Padilla J.,CSIC - National Museum of Natural Sciences | Mougeot F.,CSIC - Estación Experimental De Zonas Áridas | Leckie F.,Natural Research | Redpath S.M.,James Hutton Institute
Journal of Evolutionary Biology | Year: 2012

Numerous studies have shown positive associations between ornaments and condition, as predicted by indicator models of sexual selection. However, this idea is continuously challenged by opposite results, which reveal our lack of full understanding of how sexual selection works. Environmental heterogeneity may explain such inconsistencies, but valid field tests of this idea are currently lacking. We first analysed the relationship between condition and ornament expression from nine populations over 7years in a wild bird, the red grouse Lagopus lagopus scoticus. We then manipulated male aggressiveness at the population level by means of testosterone implants in a replicated field experiment. We found that the relationship between condition and ornamentation varied greatly between environments and became stronger when environmental conditions (ECs) were worse or when aggressiveness in the population was experimentally increased. Some ornaments may therefore reliably advertise a better condition only in adverse ECs. Considering environmental heterogeneity can help reconcile conflicting findings regarding the reliability of ornaments as indicators of condition and will help our understanding of sexual selection processes. © 2011 The Authors. Journal of Evolutionary Biology © 2011 European Society For Evolutionary Biology.

Reid T.,University of Cape Town | Kruger S.,University of Cape Town | Whitfield D.P.,Natural Research | Amar A.,University of Cape Town
Journal of Applied Ecology | Year: 2015

Summary: Concerns over CO2 emissions during energy generation and its effect on climate change have led to increases in the use of renewables, such as wind energy. However, there are also serious environmental concerns over this type of energy production due to its impacts on bats and birds. In southern Africa, bearded vultures have declined by >30% during recent decades. They are now regionally critically endangered with only around 100 active pairs remaining. This species is considered vulnerable to collision with wind turbines which are planned within their southern African range. In this study, we develop habitat use models using data obtained from 21 bearded vultures of different ages fitted with GPS tags from 2009 to 2013. We further refined these models by incorporating flying heights at risk of collision to predict important areas of use that may conflict with wind turbines. Adult and non-adult bearded vultures mostly used areas with high elevations and steep and rugged topography in the core area; adults tended to use areas in relatively close proximity to their nest sites, whereas non-adult birds used areas dispersed over the entire species range and were more likely to fly at risk-height in areas that were less used by adults. Altitudes of fixes of adults and non-adults showed that they spent 55% and 66% of their time, respectively, at heights that placed them at risk of collision. Examining the locations of two proposed wind farms in relation to our model of predicted 'at risk' usage suggested poor positioning. Indeed, one of these wind farms was located within the 1% of 'worst' (most heavily used) sites for non-adult bearded vultures suggesting that its current location should be reconsidered to reduce the impact on this vulnerable species. Synthesis and applications. We demonstrate the value of habitat use models for identifying intensively used areas, in order to greatly reduce conflicts with developments such as wind turbines. This tool is operable at the scale of regional and national development plans informed by the habitat use of potentially vulnerable species. Such models should provide important supplementary assessments of site-specific development proposals. We demonstrate the value of habitat use models for identifying intensively used areas, in order to greatly reduce conflicts with developments such as wind turbines. This tool is operable at the scale of regional and national development plans informed by the habitat use of potentially vulnerable species. Such models should provide important supplementary assessments of site-specific development proposals. © 2015 The Authors. Journal of Applied Ecology © 2015 British Ecological Society.

Weston E.D.,University of Aberdeen | Whitfield D.P.,Natural Research | Travis J.M.J.,University of Aberdeen | Lambin X.,University of Aberdeen
BMC Ecology | Year: 2013

Background: Dispersal comprises three broad stages - departure from the natal or breeding locations, subsequent travel, and settlement. These stages are difficult to measure, and vary considerably between sexes, age classes, individuals and geographically. We used tracking data from 24 golden eagles, fitted with long-lived GPS satellite transmitters as nestlings, which we followed during their first year. We estimated the timing of emigration from natal sites using ten previously published methods. We propose and evaluate two new methods. The first of these uses published ranging distances of parents as a measure of the natal home range, with the requirement that juveniles must exceed it for a minimum of 10 days (a literature-based measure of the maximum time that a juvenile can survive without food from its parents). The second method uses the biggest difference in the proportion of locations inside and outside of the natal home range smoothed over a 30 day period to assign the point of emigration. We used the latter as the standard against which we compared the ten published methods.Results: The start of golden eagle dispersal occurred from 39 until 250 days after fledging (based on method 12). Previously published methods provided very different estimates of the point of emigration with a general tendency for most to apparently assign it prematurely. By contrast the two methods we proposed provided very similar estimates for the point of emigration that under visual examination appeared to fit the definition of emigration much better.Conclusions: We have used simple methods to decide when an individual has dispersed - they are rigorous and repeatable. Despite one method requiring much more information, both methods provided robust estimates for when individuals emigrated at the start of natal dispersal. Considerable individual variation in recorded behaviour appears to account for the difficulty capturing the point of emigration and these results demonstrate the potential pitfalls associated with species exhibiting complex dispersal behaviour. We anticipate that coupled with the rapidly increasing availability of tracking data, our new methods will, for at least some species, provide a far simpler and more biologically representative approach to determine the timing of emigration. © 2013 Weston et al.; licensee BioMed Central Ltd.

Whitfield D.P.,Natural Research | Marquiss M.,Natural Research | Reid R.,Lag Na Greine | Grant J.,Natural Research | And 2 more authors.
Bird Study | Year: 2013

Capsule The breeding season diets of White-tailed Eagles and Golden Eagles in western Scotland were different, and there was no evidence of competition between the two species. Aim To test the hypothesis that the reintroduced White-tailed Eagles will have an adverse effect on Golden Eagles through competition for food. Methods Collections of prey remains at nests and regurgitated pellets during the breeding season were analysed. Temporal change in Golden Eagle territory occupancy and breeding productivity where the influence of White-tailed Eagles should be most evident was also examined. Results Diet breadth was similar between species but diet composition was significantly different, with White-tailed Eagles taking more sheep and aquatic or coastal food items, whereas Golden Eagles took more gamebirds (Galliformes), lagomorphs and other terrestrial prey. Diet overlap comparisons, between species-pairs that nested close together or far apart, rejected a hypothesis that there was competition for food, but partially supported an alternative hypothesis that diet overlap indicated abundant shared food. There was no indication that White-tailed Eagles have had any long-term effect on the breeding productivity or abundance of territorial Golden Eagles. Conclusions There is no evidence that reintroduced White-tailed Eagles are having an adverse effect on Golden Eagles through competition. © 2013 British Trust for Ornithology.

Evans R.J.,RSPB Scotland Headquarters | Pearce-Higgins J.,RSPB Scotland Headquarters | Whitfield D.P.,Natural Research | Grant J.R.,RSPB Scotland Headquarters | And 2 more authors.
Bird Study | Year: 2010

Capsule: Golden and White-tailed Eagles selected different habitats for nesting. Aim: To investigate differences in nesting habitat used by sympatrically breeding eagles in western Scotland, following reintroduction of White-tailed Eagles from 1975 onwards. Methods: Nest-site locations from national surveys in 2003-05 were entered into a geographical information system (GIS) in order to measure a set of geographic parameters for each nest site. Binary logistic regression with backwards deletion of non-significant terms was used to derive minimum adequate models at two spatial scales of the likelihood of an eagle nest belonging to one species or the other. We compared changes in occupancy between 1992 and 2003 of Golden Eagle territories inside and outside a GIS model of potential White-tailed Eagle habitat and according to proximity to White-tailed Eagle nests. Results: White-tailed Eagles nested at lower altitudes than Golden Eagles, in more wooded habitats with more open water close by, tending to nest in trees where these were present. There were 3359 km 2 of potential White-tailed Eagle nesting habitat within 25 km of existing White-tailed Eagle nests, containing 54 Golden Eagle territory centres, but we found no difference in change of occupancy for Golden Eagle territories close to White-tailed Eagles compared with those further away. Conclusion: White-tailed and Golden Eagles appear to partition nesting habitat in the west of Scotland by altitude. This corresponds with behaviour in western Norway and with the situation described in historical accounts of nest-sites in western Scotland prior to extinction of White-tailed Eagles. It is also consistent with recent studies showing little overlap in breeding season diet of Golden and White-tailed Eagles in western Scotland, and likely partitioning of foraging habitat by altitude. We conclude that the likelihood of competitive exclusion is less than previously suggested. © 2010 British Trust for Ornithology.

Evans R.J.,RSPB Scotland | O'toole L.,Golden Eagle Trust Ltd. | Whitfield D.P.,Natural Research
Bird Study | Year: 2012

Capsule The loss of eagles from large tracts of lowland and upland habitat in Britain and Ireland over the last 1500 years is attributed to human activity. Aim To estimate changes in past distribution and population size of Britain and Ireland's two native eagle species. Methods Placenames suggesting the past presence of eagles were categorized according to modern knowledge of the species' ecology. Together with documented historical locations, these sites were mapped to derive approximate former ranges. Population estimates were made for each species at about 500 and 1800 CE. Results Estimated range at about 500 CE was 110 250 km 2 for White-tailed Eagles Haliaeetus albicilla and 98 500 km 2 for Golden Eagles Aquila chrysaetos, with 44 600 km 2 of overlap. Population sizes were 800-1400 pairs of White-tailed Eagles and 1000-1500 pairs of Golden Eagles, declining to 150 and 300-500 pairs, respectively, by 1800. Conclusion Our results provide evidence for the presence within the last 1500 years of one or other species of eagle throughout much of Britain and Ireland. The influence of climate change on eagle habitat has been subsumed by the effects of habitat destruction and persecution as primary causes of absence from much of their former range. © 2012 British Trust for Ornithology.

Vergara P.,University of Aberdeen | Mougeot F.,CSIC - Estación Experimental De Zonas Áridas | Mougeot F.,Institute Investigacion en Recursos Cinegeticos | Martinez-Padilla J.,CSIC - National Museum of Natural Sciences | And 3 more authors.
Behavioral Ecology | Year: 2012

Indicator models of sexual selection predict that the expression of sexual ornaments should be condition dependent. This is only partly supported by data, as many studies do not find positive associations between ornaments and condition. The reason for this inconsistency remains poorly understood. It has been hypothesized that environmental context may explain variation in the condition dependence of sexual traits, with stronger relationships between ornaments and condition expected in harsher environments. However, field tests of this idea are scarce. We studied 9 populations of wild red grouse Lagopus lagopus scoticus over 11 years, and compared the relationship between ornamentation and body mass (an index of body condition) in relation to environmental variability. We used the abundance of a key parasite in this system, Trichostrongylus tenuis, as an index of environmental conditions. We found that both ornament expression and body mass negatively correlated with parasite infection at both population and individual levels. More interestingly, we found that the relationship between ornamentation and body mass was stronger in populations with high parasite infection levels. Our findings support the idea that the condition dependence of secondary sexual ornaments varies in relation to environmental context. In sites and years when parasites are abundant, sexual ornaments provide better signals of condition. © 2012 The Author.

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