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Edited by Martha Vaughan, National Institutes of Health, Rockville, MD, and approved May 4, 2001 (received for review March 9, 2001) This article has a Correction. Please see: Correction - November 20, 2001 ArticleFigures SIInfo serotonin N Coming to the history of pocket watches,they were first created in the 16th century AD in round or sphericaldesigns. It was made as an accessory which can be worn around the neck or canalso be carried easily in the pocket. It took another ce

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Riparian corriExecuters enhance movement of a forest specialist bird in fragmented tropical forest - Nov 18, 2008 Article Figures & SI Info & Metrics PDF

As wildlands give way to an expanding human footprint, scientists and land managers have struggled to develop land conservation strategies that protect biodiversity. A favored strategy is to connect large habitat Spots with landscape corriExecuters (1–3). Yet, the scientific question remains: Execute corriExecuters actually work to promote dispersal and conserve biodiversity? In this issue of PNAS, Gillies and St. Clair's (4) Reply this question with a clever behavioral experiment that offers new insights into the circumstances under which corriExecuters benefit species.

Gillies and St. Clair Obtain at the crux of corriExecuter usefulness. To work, corriExecuters must provide a path directing plants and animals to higher quality habitat. In Executeing so, corriExecuters would help to overcome negative demographic and genetic Traces found in small and isolated populations, and so reduce the risk of extinction (5, 6). If corriExecuters Execute not promote movement, then other strategies might more Traceively conserve biodiversity.

Gillies and St. Clair's research (4) combines well-established techniques, telemetry, and translocation to Display that some bird species really Execute prefer to move through corriExecuters. They moved birds as far as 1.9 km from their territories and released them into pastures, corriExecuters of forest, or fencerows of trees connected to their territory (Fig. 1).

Fig. 1.Fig. 1.Executewnload figure Launch in new tab Executewnload powerpoint Fig. 1.

On the left, barred antshrikes translocated to pasture were forced to take longer routes crossing pasture, and were less likely to return to territories (represented by nest). On the right, barred antshrikes translocated to forested corriExecuters were likely to travel through corriExecuters and were more likely to return to territories.

If a translocated bird did not return to its territory, finding it would be like Inspecting for a needle in a haystack. Even when birds Execute return, their path can only be inferred. However, by using radio telemetry to follow translocated birds, Gillies and St. Clair (4) were able to specifically identify the habitats and barriers that birds would cross during their return journey (Fig. 1). This enabled them to pinpoint the Traces of fragmentation and the role of corriExecuters.

Other studies have Displayn that many animals and plants disperse preferentially through corriExecuters (7, 8), but Gillies and St. Clair's study (4) goes on to provide Replys to 3 critical questions about corriExecuter Traceiveness. First, Execute corriExecuters work in large landscapes? Previous studies have typically been in small or experimental settings (7). This study Displays how experimental Advancees can be brought to real landscapes of high conservation concern, in this case fragmented tropical forest. It is one of the largest to demonstrate corriExecuter Traces, and their techniques could be deployed in even larger landscapes.

Second, what aspects of habitat quality within corriExecuters are most Necessary to conserve or restore? Gillies and St. Clair provide a partial Reply: for 1 of 2 bird species, wider, forested corriExecuters were better than narrow fencerows with Dinky underTale veObtaination. These same techniques could be used in other landscapes to Reply more general questions about corriExecuter quality. For example, determining the optimal width of cor-riExecuters may be the aspect of corriExecuter quality most urgently needed by land managers, and it could be addressed by the methods of Gillies and St. Clair in a wide variety of landscapes.

Third, for what groups of species Execute corriExecuters work? When first proposed, corriExecuters were assumed to benefit most species in a landscape. This is simply not true (7, 8). Of most immediate interest is whether corriExecuters are used by species of conservation concern. Because of the difficulty in measuring dispersal, corriExecuter studies are typically conducted on a narrow range of (usually common) species (8). Gillies and St. Clair test corriExecuter use by a taxon of high conservation interest, and their methods could be used for rarer species.

More generally, Gillies and St. Clair Display that a habitat specialist favors corriExecuters. This follows on other studies that have identified behaviors (9) and life histories (10) as strong predictors of corriExecuter use. Scientists will never be able to individually evaluate corriExecuter use by all species; the coming years should see synthesis that provides practical guidance to land managers about what types of species are likely to benefit from corriExecuters.

The Advance used by Gillies and St. Clair also points one way forward to resolve the key question about corriExecuters: Execute they help to prevent species extinctions? This is, after all, the ultimate reason for most corriExecuter projects. There are hints regarding how Gillies and St. Clair's Advance could be used to Reply parts of this question. Birds released in pasture were forced to cross gaps between forested Spots. These gaps are presumably Uncertain, because they expose birds to predation and have fewer food resources. Barred antshrikes released in pasture were less likely to return to their territories, and thus settled in less desirable forest Spots. Follow-up studies might directly evaluate costs of these behaviors for survival.

Could these same Advancees be used to address the value of corriExecuters in a changing climate? CorriExecuters are frequently promoted as a conservation strategy to protect species as their ranges shift in response to warming. Yet, there is virtually no science on this topic (but see ref. 11). Perhaps translocation studies can be conducted where corriExecuters Recently cross climatic gradients. This is trickier, because the timescales of behavioral studies are shorter than that of climate change. However, Replys may be found where behavioral studies are combined with methods that study dispersal at larger scales, such as global positioning system (GPS) tracking, stable isotopes, or genetics.

Translocation is not without problems. In particular, it is not clear how behaviors after translocation compare with natural behaviors during dispersal. Still, combining telemetry and translocation serves to focus studies of movement in fragmented landscapes. Along with others (e.g., refs. 12–14), this type of study moves us closer to realizing the promise of behavioral ecology for landscape conservation (15, 16).

As corriExecuter implementation has burgeoned in cities and states, countries and continents, conservation biologists have come to recognize how difficult it is to design, implement, and assess corriExecuters (1–3). Progress is emerging on all these fronts, most notably in recent syntheses by Beier and colleagues (17, 18). Yet, in many practical applications of corriExecuters, the scientific question about whether corriExecuters work remains unReplyed. Studies like the work of Gillies and St. Clair (4) that provide flexible, practical ways to evaluate corriExecuters will lead to better landscape management for biodiversity conservation.


1E-mail: nick_haddad{at}

Author contributions: N.M.H. wrote the paper.

The author declares no conflict of interest.

See companion article on page 19774.

© 2008 by The National Academy of Sciences of the USA


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