Dylan C. Kesler

Allowing extinction: should we let species go?

We are grateful to Bottrill et al. [1xIs conservation triage just smart decision making?. Bottrill, M.C. et al. Trends Ecol. Evol. 2008; 23: 649–654Abstract | Full Text | Full Text PDF | PubMed | Scopus (267)See all References][1] for revisiting the concept of triage in conservation biology. They argue for the use of triage when allocating resources to competing conservation demands. Contrary to simply being an efficient approach, however, we feel that application of triage has the potential to mimic carnage of the 19th century battlefields from which the practice arose [2xTriage: techniques and applications in decisionmaking. Kennedy, K. et al. Ann. Emerg. Med. 1996; 28: 136–144Abstract | Full Text | Full Text PDF | PubMed | Scopus (128)See all References][2]. Under medical triage, the most injured soldiers were allowed to die when medical resources ran short. Similarly, the model of Bottrill et al. would allow some species and ecosystems to be lost when conservation resources are scarce. This practice would have tremendous philosophical and functional consequences that should be widely debated.Allowing extinction is contrary to the fundamental concepts in conservation biology—that species have inherent value and that extinction is unacceptable [3xA Sand County Almanac. Leopold, A. See all References, 4xConservation or convenience?. Noss, R.F. Conserv. Biol. 1996; 10: 921–922CrossrefSee all References, 5xWhat is conservation biology?. Soule, M.E. Bioscience. 1985; 35: 727–734CrossrefSee all References]. The founder of modern conservation, Aldo Leopold, succinctly stated that ‘the first rule of an intelligent tinkerer is to keep all the pieces’ [3xA Sand County Almanac. Leopold, A. See all References][3]. Under a conservation triage paradigm, however, biologists would assign values to species based on the economics of their recovery. Species and systems requiring costly programs would be deemed ‘inefficient’ and therefore allowed to pass into extinction. Further, if governments that fund conservation tighten the purse strings, conservation biologists using a triage approach would have to respond by assigning more species and systems to the ever-enlarging extinction pile.A change in the philosophical stance of conservation biologists could spread well beyond the ivory tower in which triage approaches are debated. If conservationists sanction extinction in the name of efficiency, what would stop others from justifying extinctions based on interests contrary to conservation? Some would surely argue that efficiency calculations should include the impacts on corporate profits of conservation programs that hinder resource extraction. Their efficiency models might then prescribe additional extinctions when recovery interferes with economic progress. Many politicians are responsible for promoting economic growth, and for setting conservation policy. Those policymakers might have difficulty selecting between the extinction-bound species identified by efficiency-minded conservation biologists and species selected by corporate profiteers hindered by conservation programs.We agree with Bottrill et al. that there is a need for efficient distribution of conservation resources, but we disagree that resource allocation models should include extinction as an acceptable outcome for ecosystems or species falling at the ‘inefficient’ end of the spectrum. Rather, conservation biologists who are ‘squeamish’ about extinction should consider the long-term influences of their decisions and continue to allocate resources to monitoring and recovery of all species and systems. We must always retain hope for breakthroughs that could lead to recovery, even if only minimal resources are dedicated to the direst situations. Advances are a product of initiative and discovery, which cannot occur without investment. Lessons from previously imperiled species that might have been let go under a triage paradigm, including the black-footed ferret (Mustela nigripes), Mauritius kestrel (Falco punctatus) and red-cockaded woodpecker (Picoides borealis), speak to the idea of hope.

Factors affecting female space use in ten populations of prairie chickens

Conservation of wildlife depends on an understanding of the interactions between animal movements and key landscape factors. Habitat requirements of wide-ranging species often vary spatially, but quantitative assessment of variation among replicated studies at multiple sites is rare. We investigated patterns of space use for 10 populations of two closely related species of prairie grouse: Greater Prairie- Chickens (Tympanuchus cupido) and Lesser Prairie-Chickens (T. pallidicinctus). Prairie chickens require large, intact tracts of native grasslands, and are umbrella species for conservation of prairie ecosystems in North America. We used resource utilization functions to investigate space use by female prairie chickens during the 6-month breeding season from March through August in relation to lek sites, habitat conditions, and anthropogenic development. Our analysis included data from 382 radio-marked individuals across a major portion of the extant range. Our project is a unique opportunity to study comparative space use of prairie chickens, and we employed standardized methods that facilitated direct comparisons across an ecological gradient of study sites. Median home range size of females varied ;10-fold across 10 sites (3.6-36.7 km 2 ), and home ranges tended to be larger at sites with higher annual precipitation. Proximity to lek sites was a strong and consistent predictor of space use for female prairie chickens at all 10 sites. The relative importance of other predictors of space use varied among sites, indicating that generalized habitat management guidelines may not be appropriate for these two species. Prairie chickens actively selected for prairie habitats, even at sites where ;90% of the land cover within the study area was prairie. A majority of the females monitored in our study (.95%) had activity centers within 5 km of leks, suggesting that conservation efforts can be effectively concentrated near active lek sites. Our data on female space use suggest that lek surveys of male prairie chickens can indirectly assess habitat suitability for females during the breeding season. Lek monitoring and surveys for new leks provide information on population trends, but can also guide management actions aimed at improving nesting and brood-rearing habitats.

Quantitative and qualitative approaches to identifying migration chronology in a continental migrant

The degree to which extrinsic factors influence migration chronology in North American waterfowl has not been quantified, particularly for dabbling ducks. Previous studies have examined waterfowl migration using various methods, however, quantitative approaches to define avian migration chronology over broad spatio-temporal scales are limited, and the implications for using different approaches have not been assessed. We used movement data from 19 female adult mallards (Anas platyrhynchos) equipped with solar-powered global positioning system satellite transmitters to evaluate two individual level approaches for quantifying migration chronology. The first approach defined migration based on individual movements among geopolitical boundaries (state, provincial, international), whereas the second method modeled net displacement as a function of time using nonlinear models. Differences in migration chronologies identified by each of the approaches were examined with analysis of variance. The geopolitical method identified mean autumn migration midpoints at 15 November 2010 and 13 November 2011, whereas the net displacement method identified midpoints at 15 November 2010 and 14 November 2011. The mean midpoints for spring migration were 3 April 2011 and 20 March 2012 using the geopolitical method and 31 March 2011 and 22 March 2012 using the net displacement method. The duration, initiation date, midpoint, and termination date for both autumn and spring migration did not differ between the two individual level approaches. Although we did not detect differences in migration parameters between the different approaches, the net displacement metric offers broad potential to address questions in movement ecology for migrating species. Ultimately, an objective definition of migration chronology will allow researchers to obtain a comprehensive understanding of the extrinsic factors that drive migration at the individual and population levels. As a result, targeted conservation plans can be developed to support planning for habitat management and evaluation of long-term climate effects.

The role of wildfire, prescribed fire, and mountain pine beetle infestations on the population dynamics of black-backed woodpeckers in the black hills, South Dakota.

Wildfire and mountain pine beetle infestations are naturally occurring disturbances in western North American forests. Black-backed woodpeckers (Picoides arcticus) are emblematic of the role these disturbances play in creating wildlife habitat, since they are strongly associated with recently-killed forests. However, management practices aimed at reducing the economic impact of natural disturbances can result in habitat loss for this species. Although black-backed woodpeckers occupy habitats created by wildfire, prescribed fire, and mountain pine beetle infestations, the relative value of these habitats remains unknown. We studied habitat-specific adult and juvenile survival probabilities and reproductive rates between April 2008 and August 2012 in the Black Hills, South Dakota. We estimated habitat-specific adult and juvenile survival probability with Bayesian multi-state models and habitat-specific reproductive success with Bayesian nest survival models. We calculated asymptotic population growth rates from estimated demographic rates with matrix projection models. Adult and juvenile survival and nest success were highest in habitat created by summer wildfire, intermediate in MPB infestations, and lowest in habitat created by fall prescribed fire. Mean posterior distributions of population growth rates indicated growing populations in habitat created by summer wildfire and declining populations in fall prescribed fire and mountain pine beetle infestations. Our finding that population growth rates were positive only in habitat created by summer wildfire underscores the need to maintain early post-wildfire habitat across the landscape. The lower growth rates in fall prescribed fire and MPB infestations may be attributed to differences in predator communities and food resources relative to summer wildfire.

Non-Permanent Radiotelemetry Leg Harness for Small Birds

ABSTRACT I developed a modified leg harness for mounting radiotelemetry transmitters to small birds, which includes a weak link that allows telemetry equipment to be shed. Over 4 years, I mounted 62 transmitters on 49 Tuamotu kingfishers (Todiramphus gambieri) using weak-link harnesses. Kingfishers retained 86% of transmitters for the duration of monitoring periods (23–66 days) whereas 22 of 23 transmitters were shed from birds resighted after 6–15 months. Apparent mortality was no higher for radio-marked birds than for birds without transmitters. The weak-link harness is an improvement to existing transmitter attachment techniques and provides a useful, effective, and ethical means of studying bird movements.

Reevaluating the Cost of Natal Dispersal: Post-Fledging Survival of Red-Bellied Woodpeckers

Abstract. Accurate estimates of juvenile survival are critical to understanding population processes. However, information about post-fledging vital rates is lacking for most avian species because of the difficulty of following individuals after they leave the nest. We radio-tagged 43 Red-bellied Woodpeckers (Melanerpes carolinus) as nestlings. We tracked the birds for 5 months after fledging, during exploratory forays and after natal dispersal. We modeled the influence of intrinsic, temporal, social, and landscape factors with the potential to affect survival during the post-fledging period. Estimates of post-fledging survival were best explained by fledgling age. Predictions of weekly survival rates were 0.94 for birds 1 week after fledging, then quickly increased to over 0.99 for birds 7–22 weeks after fledging. We calculated period survival for the entire 5 months as 0.80 (95% CI: 0.65–0.90). We observed no mortalities after the birds departed natal territories, suggesting that exploratory and dispersal behaviors are not costly in this species.

Crash and rebound of indigenous populations in lowland South America

Lowland South America has long been a battle-ground between European colonization and indigenous survival. Initial waves of European colonization brought disease epidemics, slavery, and violence that had catastrophic impacts on indigenous cultures. In this paper we focus on the demography of 238 surviving populations in Brazil. We use longitudinal censuses from all known indigenous Brazilian societies to quantify three demographic metrics: 1) effects of European contact on indigenous populations; 2) empirical estimates of minimum viable population sizes; and 3) estimates of post-contact population growth rates. We use this information to conduct population viability analysis (PVA). Our results show that all surviving populations suffered extensive mortality during, and shortly after, contact. However, most surviving populations exhibit positive growth rates within the first decade post-contact. Our findings paint a positive demographic outlook for these indigenous populations, though long-term survival remains subject to powerful externalities, including politics, economics, and the pervasive illegal exploitation of indigenous lands.

Translocation of Tuamotu Kingfishers, Postrelease Exploratory Behavior, and Harvest Effects on the Donor Population

Abstract: Conservationists previously described the need for research into using translocation to rescue threatened populations. We conducted an experimental translocation of Tuamotu kingfishers (Todiramphus gambieri gertrudae) to provide foundational information about movement ecology and inform conservation planning for the critically endangered bird. We captured and radio-marked mated pairs of kingfishers on Niau Atoll, French Polynesia, where approximately 125 individuals compose the last remaining population of Tuamotu kingfishers. One bird from each pair was translocated to a reintroduction site on the opposite side of the island, and the other pair member was released back onto the home territory. Home-ranging pair members remained on territories and used habitats disproportional to availability, as determined by Brownian bridge analysis. Translocated individuals made multiple forays from the release site to explore the surrounding landscape, during which habitats were used in proportions similar to availability. The exploratory behavior resembled that of dispersing juvenile birds, which suggested that adults retain the ability to explore, and that dispersal theory may be a useful basis for planning translocations. Vacancies on donor territories were filled within 1–10 days. Our results indicated that translocation was not effective for range expansion on Niau because birds readily returned to donor areas; however, translocation to other islands remains a potential conservation strategy for Tuamotu kingfishers.

Habitat and social factors influence nest-site selection in Arctic-breeding shorebirds

ABSTRACT Habitat selection theory suggests that shorebirds should choose nest sites that maximize survival and fitness. We investigated how habitat, and proximity to conspecific or heterospecific nesting birds, was related to nest-site selection in American Golden-Plovers (Pluvialis dominica), Dunlin (Calidris alpina), Long-billed Dowitchers (Limnodromus scolopaceus), Pectoral Sandpipers (C. melanotos), Red Phalaropes (Phalaropus fulicarius), and Semipalmated Sandpipers (C. pusilla) in Barrow, Alaska, USA, between 2005 and 2012. We used remote-sensing data to link habitat information to used and unused nest sites, and we measured distances from nests to other nearby nesting shorebird neighbors. Results from an information-theoretic approach to identify best-approximating models indicated that all species selected nest sites on the basis of both habitat and social cues. Macroscale tundra moisture level within 50 m of the nest, which was closely associated with vegetation community, was an informative variable for Dunlin, Long-billed Dowitcher, and Red Phalarope, which all selected wetter habitat. Enhanced tundra microrelief increased the probability of nest-site selection for American Golden-Plover, Long-billed Dowitcher, Pectoral Sandpiper, and Semipalmated Sandpiper. American Golden-Plover, Dunlin, Pectoral Sandpiper, and Semipalmated Sandpiper selected sites farther from conspecific nests than predicted by chance. Our results indicate that shorebirds select nest sites on the basis of habitat features, and that some are also influenced by proximity to other nesting shorebirds. These findings indicate that shorebirds select nests that are likely to aid incubation abilities, reduce predator detection of nesting birds, enhance detection of predators, enhance foraging, and reduce competition from conspecifics. The variable needs of the different Arctic-breeding shorebirds indicate that climate change will have both beneficial and harmful consequences. Our habitat models may be useful for predicting areas of high shorebird importance throughout the Arctic Coastal Plain, allowing mitigation of proposed anthropogenic developments.

Apparent foraging success reflects habitat quality in an irruptive species, the Black-backed Woodpecker

ABSTRACT Dramatic fluctuations in food resources are a key feature of many habitats, and many species have evolved a movement strategy to exploit food resources that are unpredictable in space and time. The availability of food resources may be a particularly strong determinant of habitat quality for irruptive bird species. We studied the apparent foraging success of Black-backed Woodpeckers (Picoides arcticus), an irruptive species that responds opportunistically to pulsed food resources in burned forests and mountain pine beetle (MPB) infestations. Prior investigations revealed that the highest population growth rates of Black-backed Woodpeckers occurred in habitat created by summer wildfire, with intermediate population growth rates in MPB infestations, and the lowest population growth rates in habitats created by prescribed fire in fall. We tested whether apparent foraging success was associated with known habitat quality in order to assess the potential for food availability to regulate population growth. We counted the number of successfully captured wood-boring beetle larvae and “small” prey on each tree that a Black-backed Woodpecker used for foraging and modeled these counts as a function of habitat, tree diameter, number of years postfire, and tree disturbance category. Total apparent foraging success (the sum of observed captures of wood-boring beetle larvae and small prey per tree) did not vary across habitats, but woodpeckers foraging in habitats created by summer wildfire were expected to capture 2.2 and 2.0 times more wood-boring beetles than woodpeckers foraging in habitats created by fall prescribed fire and MPB infestations, respectively. These results suggest that the availability of food resources may contribute to population regulation in this irruptive species. Furthermore, population growth in irruptive species may be highly sensitive to the availability of preferred food resources. Forests recently burned by summer wildfires provide relatively abundant food resources for Black-backed Woodpeckers and represent high-quality habitat for this species of conservation concern.