Lead (Pb) toxicity is a threat to scavenging wildlife across the globe. To allow inexpensive measurement of long-term lead exposure from archived wildlife tissues, portable X-ray fluorescence (XRF) devices have been optimized to measure lead concentrations in bone samples from avian species. In this study, we assessed portable XRF for hair lead measurement in an Australian mammalian scavenger, the threatened Tasmanian devil (Sarcophilus harrisii). We attempted to first validate the method by analysing relatively large (~1.0 g) hair samples from 39 deceased animals initially with XRF, and then with inductively coupled plasma mass spectrometry (ICP-MS) (validation study). We then measured lead concentrations via XRF only in a further 61 hair samples taken from live devils trapped in a plantation forestry landscape, where devils may scavenge on browsing marsupials that are regularly culled using lead ammunition (plantation study). Portable XRF hair lead measurement demonstrated a positive correlation with ICP-MS results (R2 = 0.95), although the relationship was weak at low lead concentrations. In the validation study, 95% of sampled Tasmanian devils had relatively low lead levels (≤ 3 mg/kg), but the remaining two animals showed considerably elevated lead levels (> 15 mg/kg), suggesting that harmful long-term lead exposure can occur in this species. In the plantation study, lead levels were comparable to those found in the hair of mammals in other studies, though a higher proportion (11%) of devils showed levels > 3 mg/kg than in the validation study, suggesting devils may have higher exposure to lead in a landscape subjected to regular culling of browsing mammals. Our results suggests that portable XRF is a promising emerging technology, and after some refinement, may allow non-invasive real-time measurement of lead concentrations in the hair of mammals.
Landscape modification is a major threat to carnivores worldwide, but modified landscapes can also provide important habitat for these species, as protected areas alone are insufficient. Understanding how carnivores move through modified landscapes, such as production forests, can inform management strategies to improve the value of these landscapes to carnivores. Little is known about habitat selection by marsupial carnivores in production forests, where they occupy a similar ecological niche to their more well-studied eutherian counterparts. We used GPS tracking, Hidden Markov Models, and Manly’s selection ratios to identify the habitat selected in 3 movement states indicating resting/feeding, foraging, and travel by the largest marsupial carnivore, the Tasmanian devil (Sarcophilus harrisii), in a timber plantation-dominated landscape. Devils did not show preferences for any of native forest, native grassland, and plantation in any movement state. Within plantations, devils preferred a plantation age of 4–7 years (selection ratio [wi] = 1.52) and slightly avoided older plantations (8–13 yearswi= 0.74, 14+ yearswi= 0.65). Devils preferred roads (state 1:wi =2.71, state 2:wi= 2.48, state 3:wi= 2.97) and plantation edges (state 1:wi =2.38, state 2:wi= 2.24, state 3:wi= 2.78) in all movement states, and moved faster on roads (0.06 [95% CI 0.04 to 0.09] m.sec-1) and edges (0.08 [0.06 to 0.10] m.sec-1) than away from them, indicating they use them for foraging and travel. No measured habitat variables influenced devil home range size. To support devils in plantation landscapes, we recommend maintaining a heterogeneous landscape of different plantation ages and native remnants and reducing the risk of vehicle collisions by minimizing forestry traffic at night. Tasmanian devils share similar adaptable traits to generalist eutherian carnivore species in their use of modified landscapes. Plantations can provide valuable habitat for this and other threatened predator species.
1. Unmodified forests are increasingly rare worldwide, with forestry a major contributor to habitat modification. Extending conservation practices beyond protected areas is important to conserve forest ecosystems. 2. We investigate the response of native mammalian carnivores (both Order Carnivora and Family Dasyuridae) to production forests globally, including harvested native forest and timber plantations. We examine how carnivores recorded in production forests use these forests versus other land uses, particularly native and unharvested forest; how habitat use relates to threatened status, body size, diet, and harvesting method; carnivore responses to habitat features within production forests; and carnivore denning, breeding, and predation behaviour in production forests. 3. We review 294 studies recording 132 carnivore species in production forests. Carnivores generally show higher use of native and unharvested forests and lower use of agricultural land than production forests. Threatened species and large carnivores respond more negatively to production forests than non-threatened species and small carnivores respectively. Hypercarnivores respond more negatively than omnivores to plantations compared to native forest, but there was no difference in the use of harvested and unharvested native forest between these dietary groups. 4. Surprisingly, a high proportion of carnivore species use clearfelled more than unharvested native forest. In forest with partial harvesting or reduced-impact logging, most species show no difference in use between harvested and unharvested forest. 5. Carnivores generally respond positively to habitat features such as riparian areas and coarse woody debris. Several carnivores were recorded denning and breeding in production forests. Production forests often influence the prey availability, hunting success, and diet of carnivores. 6. We show that many carnivores use production forests, and how they respond to production forestry varies with species traits. We recommend that production forests are managed as valuable carnivore habitat, and highlight strategies to enhance the use of these forests by carnivores.
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