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Noticias de ornitología

 
Dec. 14, 2012 — A study of closely-related bird species has found that they do not coexist in the same region because they remain too ecologically similar and will out-compete each other, not because of geographical barriers or unsuitable habitats.

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Campylorhamphus trochilirostris. (Credit: Joseph Tobias)

Oxford University scientists examined 'sister' species -- species that are each other's closest relatives -- of the 'ovenbird' family from South America. They compared data on when these species diverged and where they live today and found that those that have been separated for longest and have evolved very different beaks were able to coexist more rapidly after they became two separate species.
The findings suggest that species displaced due to climate change may not be able to survive in what appears to be a suitable new habitat because a related species already living there will out-compete them for resources.
A report of the research appears this week in Ecology Letters.
'Competitive exclusion between species is generally thought to be limited to relatively small spatial scales, such as between individual birds or across local patches of habitat,' said Dr Alex Pigot of Oxford University's Department of Zoology, lead author of the report. 'In our work we are able to show that competition is a major factor responsible for excluding closely-related species from entire regions. The key was being able to rule out other explanations like geographical barriers, such as rivers, or unsuitable habitats from being the main barriers to 'sister' species co-existing.'
'Ovenbirds' (Furnariidae), so called because in some species their domed nests resemble a traditional Dutch oven, are found throughout South America; there are hundreds of species inhabiting a range of environments from deserts and grasslands to tropical forests. The Oxford team chose to study them because their very diverse beaks give useful information on how related species have evolved to fill particular ecological niches.
'The beak is the main tool used by birds for capturing and consuming food items and so has been moulded by natural selection to fit this purpose,' said Dr Pigot. 'In ovenbirds some species have evolved bizarrely long curved bills in order to prise insects from bamboo stems or beneath the bark of trees, but only one such species tends to live in any given place. Our results suggest that it can take a long time to evolve a foraging niche different enough to allow coexistence amongst related species.'
As environments become hotter or drier, for instance due to climate change, it has been generally assumed that species will track suitable conditions and move to new locations. This new research shows that the area of suitable habitats could be much smaller than current estimates suggest, as many regions will already be occupied by related species that will out-compete any newcomers. This implies that the full impact of environmental change cannot be understood without considering competitive interactions between species.


Story Source:
The above story is reprinted from materials provided by University of Oxford.

ScienceDaily:

Dec. 14, 2012 — A new tool developed by the Wildlife Conservation Society (WCS) and its partners is being used by scientists and land managers to model how noise travels through landscapes and affects species and ecosystems -- a major factor in land and wildlife management decisions such as where to locate new roads or recreational trails.

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“A new tool is being used by scientists and land managers to model how noise travels through landscapes and affects wildlife.” (Credit: Julie Larsen Maher, copyright WCS)

The tool, SPreAD-GIS, uses spatial data layers to predict how sound spreads from a source through the surrounding landscape and how it is affected by such factors as vegetation, terrain, weather conditions, and background sound levels. By determining how sound propagates, potential impacts to wildlife can be forecasted. Such impacts can include reducing habitat quality, altering the geographic distribution of species, disrupting animal communication, and causing stress.
In an example discussed in the paper, the sensitivities of humans and owls to motor vehicle sound levels were compared. The results of the SPreAD-GIS analysis showed that in the same location, motor vehicle noise would affect owls in an area 45 percent larger than the area affected for humans. Exposure to noise may affect an owl's livelihood as the animal relies on its acute sense of hearing to detect even the slightest movement of its prey.
WCS Scientist Sarah Reed said, "Exposure to human-caused noise can change the game for many species. Those species that are less tolerant of noise can be put at a disadvantage and ultimately, this may result in a loss in biodiversity. By predicting what the effects of sound will be on a bird or mammal species in advance, we can more adequately balance our land-use planning decisions with conservation considerations."
Reed and colleagues are currently using SPreAD-GIS and field measurements of motor vehicle noise to forecast the area affected for bird and mammal communities in the Sierra National Forest in California. In addition, the model has been downloaded by hundreds of users in more than 25 countries and used for diverse education, research, and management applications. This includes modeling potential noise propagation from roads, recreational activity, heavy equipment, residential development, and natural resource extraction.
Reed added, "Most existing tools are used to understand noise in human-dominated environments and don't incorporate factors affecting noise propagation in natural systems. This tool is free and relatively user-friendly for the average desktop GIS user, and comes at a time when ecologists are just beginning to understand the critical role that sound disturbances play in affecting wildlife."
Reed started the SPreAD-GIS project as a scientist with The Wilderness Society (TWS) and completed it as a Smith Conservation Research Fellow and WCS employee. The model is available for download from TWS's Landscape Collaborative (www.landscapecollaborative.org) website.
The tool is described in the November print edition of the journal Environmental Modeling & Software. Authors include Sarah E. Reed of the Wildlife Conservation Society and Colorado State University, Jennifer L. Boggs, formerly of The Wilderness Society, and Jacob P. Mann.


Story Source:

The above story is reprinted from materials provided by Wildlife Conservation Society.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Ruth Muñiz con águila harpía herida. Fuente El PaísEl 21 de octubre a las 19h30 en el Topic de Tolosa tendrá lugar una conferencia de la bióloga Ruth Muñiz bajo el título ‘Ruth Muñiz y el águila harpía: donde la ciencia y los sueños se hacen realidad’.
La entrada es libre y será presentada por Alberto Luengo uno de los habituales organizadores de las jornadas tolosarras de viajes, naturaleza y antropología Amalur.

Fuente: ScienceDaily

Dec. 13, 2012 — Scientists have developed a new method for studying parasite numbers in the stomachs of individual seabirds in the wild. The technique enables the recording of video footage of worms inside seabird stomachs and is an important step forward in understanding the impact of parasites on seabird populations.

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Shag on the Isle of May. (Credit: Mark Newell / Centre for Ecology & Hydrology)

The research is published today (Dec. 13, 2012) in the scientific journal Methods in Ecology and Evolution.
The research team trialled the use of endoscopy, often used in human and veterinary medicine but rarely in field situations, to measure natural parasite loads, or burdens, of European shags, a member of the cormorant family. The new study is part of ongoing work into how different factors such as gut parasites might affect the breeding success or survival of seabirds.


Shags have nematode worms (Contracaecum rudolphii) in their stomachs, obtained from their fish diet. These worms feed directly on food obtained by the birds, reducing for the food available to both parent and chicks.
The team behind today's study was led by Dr Sarah Burthe from the NERC Centre for Ecology & Hydrology (CEH) in the UK. Dr Burthe and colleagues from CEH collaborated with scientists from the University of Edinburgh (UK), Biomathematics and Statistics Scotland (UK), Aarhus University, (Denmark) and the Natural History Museum, London (UK). The study was carried out on the Isle of May NNR, an important seabird colony off the east coast of Scotland which has been intensively studied since the 1970s.


Dr Burthe said, "Endoscopy is used routinely in veterinary and human medicine but to our knowledge has not been used to measure parasites in wild animals. Our new method using an endoscope is a rapid, reliable and repeatable way of looking at gut parasites in European shags which has no obvious adverse effects."
The study found that all birds had parasitesranging from low burdens of several worms through to high burdens of more than 40 worms. Burdens were significantly higher in males and in late breeders. There was a slight seasonal decline in worm counts within individuals.


One way to get an understanding of the impact of parasites on breeding success and survival is to treat birds with an anti-parasite drug to reduce or remove worm burdens and then compare to untreated birds. However, until now the lack of a method to measure parasite numbers effectively has made it difficult to know whether such treatments have worked. The use of the endoscope enabled the researchers to conclude that, at a suitable dose, the anti-parasite drug completely removed nematode worms from the stomach of treated shags.
Study co-author Dr Francis Daunt, a population ecologist at the NERC Centre for Ecology & Hydrology said, "Being able to monitor individual parasite burdens is a major step forward in this field of research. We are hopeful this new technique could be applied to other wild animal systems, possibly including reptile, mammal and other bird hosts."


Dr Burthe added, "Endoscopy opens up some interesting research questions, enabling us to more fully explore the role parasites play in impacting the breeding success and survival of seabirds, particularly how impacts may vary with changes in prey availability."


Why use endoscopy to study parasites in wild seabirds?


Parasites are an important part of ecosystems, occurring in all wild animal species and playing an important part in the evolutionary process. Relatively few studies have focussed on gut parasites in wild animals, in part because it is very difficult to measure parasite levels in hosts without resorting to examining animal carcasses or counting eggs in faeces, both of which can be unreliable measures. Some previous ways of studying parasites in wild populations have involved killing birds.


The endoscopy method is rapid and well suited to species that routinely swallow large prey items and/or where chicks feed by inserting their heads into the parent's throat. Observations from this study confirmed that Shags went straight back to their broods and their breeding success was as high as pairs that were not endoscoped.


Endoscopy is a licensed procedure and was undertaken under a Home Office Project Licence and conducted by trained personnel. The work had full ethical approval from the University of Edinburgh and CEH's Ethics Committees and the Home Office. As this was a novel technique that is usually undertaken in a clinical setting, the work was initially carried out under full independent veterinary supervision.


Story Source:

The above story is reprinted from materials provided by Centre for Ecology and Hydrology.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

  1. Sarah Burthe, Mark A. Newell, Gidona Goodman, Adam Butler, Thomas Bregnballe, Eileen Harris, Sarah Wanless, Emma J.A. Cunningham, Francis Daunt. Endoscopy as a novel method for assessing endoparasite burdens in free-ranging European shags (Phalacrocorax aristotelis). Methods in Ecology and Evolution, 2012; DOI: 10.1111/2041-210x.12015

Cartel Segundas Jornadas de las Aves. Autor:

En los próximos días, del 16 al 30 de septiembre y primer fin de semana de octubre, se celebrarán las "Segundas Jornadas de las Aves" en las cuales se desarrollarán diferentes actividades en Etxalar, Auritz-Burguete y el Parque Natural del Señorío de Bertiz.

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