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NEWS TIPS FROM THE April 2004 ISSUE OF CONSERVATION BIOLOGY the Journal of the Society for Conservation Biology
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18th ANNUAL MEETING, SOCIETY FOR CONSERVATION BIOLOGYJuly 30-August 2, 2004, New York City
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While many female animals are choosy about their mates, arranged marriages are often necessary in captive breeding programs. The problem is that females reject and even fight with unwanted males. New research in harvest mice shows that odors from desired males can make undesired males more alluring.
"Could we make unpreferred males more attractive?" asked Craig Roberts and Morris Gosling, both of the University of Newcastle, UK, in the April Conservation Biology.
The answer, at least for harvest mice, is yes. Harvest mice are difficult to breed in captivity because the females bite and fight with incompatible males. Incompatible pairs of some captive-bred species go even further - clouded leopards, for example, can injure and even kill each other. One solution may be to figure out why females choose particular males and then try to boost the appeal of the rejected males. In many species, females pick mates based partly on odor because dominant males mark their territories with smelly urine.
Roberts and Gosling tested whether odor could sway mate choice in harvest mice in a captive breeding program. To see if odors from attractive males could make females more interested in unattractive males, the researchers first gave each female the choice between two males at the beginning of the experiment, then collected urine-markings from the preferred male and put them in the unpreferred male's cage every day for a week, and finally gave the female the choice between the same two males again at the end of the experiment.
The results showed that female preferences were indeed swayed: females spent about 30% more time with the unpreferred males at the end of the experiment than they had at the beginning. While female preferences were not reversed, the fact that the unpreferred males were more attractive at all is promising for captive breeding programs, says Roberts.
The researchers believe that this female preference shift is due to the fact that the odor from preferred males made the unpreferred males scent-mark four times as often as they had initially. "We think transferring the odor of competitors alters the social environment of the unpreferred males by increasing the rate of simulated competition, with effects on their behavior (scent-marking rate) and apparently female preferences," says Roberts.
In a second experiment to see if familiarity could make females more interested in particular males, Roberts and Gosling put urine-markings from a male in each female's cage every day for 10 days and then gave her the choice between the familiar male and an unfamiliar male. The results showed that the females spent about twice as much time with the familiar males. In addition, the females were far less aggressive towards the familiar males, attacking and biting them only 6% as often as unfamiliar males. This suggests that female harvest mice would be more likely to mate with familiar males. However, the researchers caution that this will not hold for all species, pointing out that female naked mole-rats prefer unfamiliar males.
Swaying mate choice with odor would be easier and cheaper than artificial insemination and other current approaches to circumventing incompatibility in captive animals. Using odor also has the benefit of preserving animals' natural mating behavior. "Transferring scent marks between cages or collections is an effective and practical behavioral means of improving success in conservation breeding programs," say Roberts and Gosling.
CONTACT:
Craig Roberts: +44 191 222 6265, craig.roberts@ncl.ac.uk
Morris Gosling: +44 191 222 5232, l.m.gosling@ncl.ac.uk
WEBSITE:
Craig Roberts' research
http://www.staff.ncl.ac.uk/craig.roberts/research.htm
BIRDSONG RECORDINGS CAN ATTRACT BIRDS TO BEST HABITAT
Black-capped vireos sing with call boxes, settle nearby
Finding the best places to nest can be tricky for songbirds because people have degraded their habitats, introducing predators and increasing populations of nest parasites. New research shows that birdsong recordings can help guide black-capped vireos to the safest places to nest and breed.
"Our results provide the first experimental evidence that territorial songbirds use each others' presence when deciding where to settle and suggest that this attraction may provide a valuable conservation tool," says Michael Ward, who presents this work with Scott Schlossberg in the April Conservation Biology. Both researchers are at the University of Illinois, Urbana-Champaign.
Long used to reestablish birds that breed in colonies, bird call recordings had been little tested in territorial species. Black-capped vireos are endangered territorial songbirds that breed in the shrublands of Texas, Oklahoma and northern Mexico. The vireo's main threats are habitat loss and brown-headed cowbirds, which parasitize other birds by laying eggs in their nests. While cowbirds are native, their populations are artificially high because they thrive in areas with agriculture and cattle grazing.
To see if conservationists could use birds' calls to attract them to cowbird-free habitat, Ward and Schlossberg played recordings from call boxes during two spring breeding seasons in and around Fort Hood, Texas. The study sites initially had few if any black-capped vireos. Five sites were in Fort Hood, where cowbirds are controlled, and two sites were on private property where cowbirds are not controlled.
The researchers found that call boxes could help reestablish songbird populations. Vireos were attracted to the call boxes and often even sang with them, much as they sing at the edges of each others' territories. During the first year, study sites without call boxes had no vireos while those with call boxes had a total of 73 vireos, many of which bred. "Being able to attract individuals to predetermined locations would allow managers to more effectively and efficiently manage endangered or declining species," say Ward and Schlossberg.
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| Cd player and apparatus used to broadcast vireo vocalizations |
Moreover, during the second year, sites that no longer had call boxes continued to have many vireos. This suggests that one year of playing birdsongs may be enough to establish a population.
The researchers also found that while the vireos nested successfully in the sites with cowbird control, all the nests were parasitized in the sites without cowbird control. This underscores the importance of managing the birds' habitat. "Simply attracting birds to a new site will not provide conservation benefits unless limiting factors are controlled," say the researchers.
CONTACT:
Mike Ward: 217-333-2235 (office), 217-621-8759 (cell), mpward@uiuc.edu
Scott Schlossberg: 217-333-2235 (office), 812-345-3917 (cell), schlssbr@uiuc.edu
PUBLIC ACCESS KEY TO SUPPORT FOR WETLAND MITIGATION
More important than protecting endangered species
Because many wetlands are destroyed for roads, flood control and other public works, the public must pay the hefty costs of conserving or creating wetlands elsewhere. What makes people willing to pay? A new survey shows that public access is one of things they care about most.
"Public access may be critically important to gaining public support for mitigation projects," say Stephen Swallow and Dana Bauer, both of the University of Rhode Island, Kingston, and Nicole Cyr, who did this work while at the University of Rhode Island and is now at Tufts University in Boston, Massachusetts, in the April Conservation Biology.
The policy and science of wetland mitigation are somewhat at odds in the U.S. The "no net loss of wetlands" policy ranks restoration first, creation second and preservation third. In contrast, conservationists favor preservation first and restoration second, and view creation as a last resort. This is because new and restored wetlands are no substitute for natural wetlands. But no one knows where the public, which foots the bill, stands on this debate.
To learn more about what people want from wetland mitigation, the researchers surveyed 289 people in South Kingstown, Rhode Island. The survey assessed the relative importance of factors including cost, size, public access, presence of endangered species, and type of mitigation (preservation, restoration or creation). The people surveyed were familiar with the Galilee Bird Sanctuary Salt Marsh Restoration Project, a roughly 125-acre Rhode Island Department of Transportation wetland mitigation project.
Swallow and his colleagues found that public access was more desirable than the presence of endangered species in wetland mitigation projects. People were willing to pay twice as much for projects with boardwalks as for those with endangered species (about $54/year vs. about $25/year). Moreover, using a model of how people would vote given the choice of four mitigation scenarios, the researchers found they would choose a restored wetland with public access over a natural wetland that was bigger and cheaper (the former got about half of the votes while the latter got about a third).
Knowing that people want access to wetlands can help conservationists tailor mitigation projects to both please them and meet conservation goals. "If the cost of providing public access, such as a boardwalk or viewing tower, is relatively small, the gain in public support for mitigation expenditures may well allow a substantial expansion of the number of acres involved in mitigation projects and thus a greater increase in the amount of habitat conserved," say Swallow and his colleagues.
CONTACT:
Stephen Swallow: 401-874-4589, swallow@uri.edu
Dana Bauer: danabauer@uri.edu
Nicole Cyr: nicole.poirier@tufts.edu
WEBSITES:
Rhode Island Habitat Restoration: Restoring Coastal Habitats
http://www.edc.uri.edu/restoration/html/backgrnd.htm
University of Rhode Island's Office of Marine Programs
omp.gso.uri.edu
CONSERVING NATURALLY SMALL POPULATIONS
Some ice-age survivors will never "recover"
Iberian lynx (left) and Imperial eagle(Photos: Donana National Park, Spain)
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Many species that survived ice-ages or evolved on islands have small populations naturally, making extinction a constant threat. A new analysis of two such relict species - the Spanish Imperial eagle and Iberian lynx - argues that rather than trying to increase these populations, managers should just try to stave off extinction for as long as possible.
"Recovery plans aimed at getting those species off the endangered list are doomed to fail because their populations are and have been chronically scarce," say Miguel Ferrer and Juan Negro, both of the Estacion Biologica de Donana C.S.I.C., Sevilla, Spain, in the April Conservation Biology.
The Spanish Imperial eagle and Iberian lynx are found only in Spain's Iberian Peninsula, where the Mediterranean forests and scrublands they prefer have been cut by more than half over the last century. Despite 20 years and millions of dollars worth of efforts to boost their populations, the two species are close to extinction. There are fewer than 200 breeding pairs of the eagle and only about 150 lynx left.
The problem is that the eagle and lynx are naturally prone to extinction, say Ferrer and Negro. Genetic studies indicate that the two species originated nearly a million years ago, during a 100,000-year glacial period when the Iberian Peninsula was a major refuge for Eurasian animals. The ancestors of the eagle and lynx presumably preyed on the abundant rabbits, which were restricted to the Iberian Peninsula until relatively recently (10,000 years ago). Today this eagle and lynx still rely almost entirely on rabbits for food.
"Their extreme dietary adaptations made them prisoners of the rabbit in its formerly small distribution area," say Ferrer and Negro. Being limited to a small area obviously limits a species' abundance, and smaller populations are more likely die out sooner.
While the researchers believe that the Iberian eagle and lynx cannot be "saved", the species' extinction could be delayed. Simply maintaining the current populations of the Iberian eagle and lynx is "an enormous challenge that will demand continuous action from wildlife managers," they say. Ferrer and Negro recommend managing the two species jointly by increasing the rabbit populations and preserving the Iberian Peninsula scrublands that they both depend on.
CONTACT:
Miguel Ferrer: 954 232 340 (office), 609 587 869 (cell), mferrer@ebd.csic.es
Juan Negro: 954 232 340, negro@ebd.csic.es
WEBSITE:
Donana Biological Station
http://ebd03.ebd.csic.es/eng/iinvestig44.html
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