Socio-economic and spatial determinants of anthropogenic predation on Yellow-spotted River Turtle, Podocnemis unifilis (Testudines: Pelomedusidae), nests in the Brazilian Amazon: Implications for sustainable conservation and management

Norris, D. Ryan; Michalski, Fernanda

doi:10.1590/s1984-46702013000500003

Cited by 33 publications

(48 citation statements)

References 23 publications

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“…Additionally, the settlements in Bolivia were selected because residents ate turtle meat. In contrast the riverine residents in our study rivers do not appear to target adult turtles for their meat (Norris & Michalski, ). Indeed Coway‐Gomez () attribute the observed differences in basking adults directly to the effect of hunting pressure reducing the abundance of adults along the rivers.…”

Section: Discussionmentioning

confidence: 99%

“…The other three variables, related to the riverine settlements, were: (1) distance from the centroid point of each nest‐site to the nearest house (based on GPS fixes obtained in situ at the sampling period); (2) presence of houses within a 1 km buffer; and (3) number of houses within a 5 km buffer. Buffer zones were set based on usual distances covered by the locals when fishing [<1 km, Norris & Michalski ()] and P. unifilis movement patterns [home ranges average 5.2 km, Naveda‐Rodríguez, Cueva & Zapata‐Ríos ()].…”

Section: Methodsmentioning

confidence: 99%

“…Most nesting occurs on beaches and river banks with dry and relatively exposed sandy-silty substrates (Escalona & Fa, 1998;Ferreira J unior & Castro, 2003), but nesting has also been recorded in pasture (Santos, 2013) and even on top of crocodilian nests (Maffei & Da Silveira, 2013). The nests of P. unifilis typically contain 20-30 oval hard shelled eggs (Ojasti, 1996;Norris & Michalski, 2013) and adult females weigh 5-11 kg (Ojasti, 1996). Both eggs and adults of P. unifilis have been exploited since the pre-colonial period (pre 18th century) and are still consumed by indigenous and riverine communities across Amazonia (Smith, 1979;Harju, Sir en & Salo, 2018).…”

Section: Study Speciesmentioning

confidence: 99%

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Nest removal by humans creates an evolutionary trap for Amazonian freshwater turtles

et al. 2019

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Nest‐site selection exerts a fundamental maternal effect on offspring fitness in oviparous species. In many freshwater turtles, females do not care for their eggs after oviposition but rather rely on a nest's micro‐environment to incubate developing embryos although linkages between oviposition choices and overall fitness remain poorly evaluated. We tested predictions derived from multiple hypotheses to examine nesting patterns of the yellow‐spotted river turtle Podocnemis unifilis, a species imperiled by egg harvesting by humans throughout its range, based on data collected from 73 nesting sites along 118 km of river in the eastern Brazilian Amazon. Nesting area size largely explained nest‐site selection by turtles, but only weakly explained turtle egg harvesting by humans. Despite the wide availability of alternative nesting habitats, turtles do not appear to be capable of avoiding hazardous nesting sites associated with increased egg harvesting by humans. Because signals used by female turtles to select nesting areas are apparently not sufficient for avoiding nesting along rivers accessible to humans, direct conservation action will be vital for persistence of these and likely other Amazonian freshwater turtles.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Study Speciesmentioning

confidence: 99%

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Nest removal by humans creates an evolutionary trap for Amazonian freshwater turtles

et al. 2019

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“…manioc flour) in local markets. There are some 54 properties upstream of the nearest town (Porto Grande 67 ). There has never been any expansive clearcutting in the region and there are no monocultures (e.g.…”

Section: Methodsmentioning

confidence: 99%

Big trees drive forest structure patterns across a lowland Amazon regrowth gradient

Caron¹,

Chuma

Sandi

et al. 2020

Preprint

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1Degraded Amazonian forests can take decades to recover and the ecological results of natural 2 regeneration are still uncertain. Here we use field data collected across 15 lowland Amazon 3 smallholder properties to examine the relationships between forest structure, mammal diversity, 4 regrowth type, regrowth age, topography and hydrography. Forest structure was quantified together 5 with mammal diversity in 30 paired regrowth-control plots. Forest regrowth stage was classified into 6 three groups: late second-regrowth, early second-regrowth and abandoned pasture. Basal area in 7 regrowth plots remained less than half that recorded in control plots even after 20-25 years. Although 8 basal area did increase in sequence from pasture, early to late-regrowth plots, there was a significant 9 decline in basal area of late-regrowth control plots associated with a decline in the proportion of 10 large trees. There was also contrasting support for different non-mutually exclusive hypotheses, with 11 proportion of small trees (DBH <20cm) most strongly supported by topography (altitude and slope) 12 whereas the proportion of large trees (DBH >60cm) supported by plot type and regrowth class. These 13 findings support calls for increased efforts to actively conserve large trees to avoid retrogressive 14 succession around edges of degraded Amazon forests. 15 16 17 Healthy tropical forests provide goods and services to human populations. Yet tropical forests show 18 worrying rates of forest loss with an elevated loss / gain ratio and a statistically significant trend in 19 annual forest loss of 2101 km 2 /year 1 . One option to revert tropical forest loss is the restoration of 20 degraded forests and deforested landscapes 2,3 . Although the post-disturbance restoration of forest 21 ecosystems often involves passive restoration strategies (i.e. natural regeneration), the ecological 22 results of this type of restoration are still uncertain 2-4 . 23 Continuing widespread forest losses across Amazonia compromises vital ecosystem services 24 such as carbon storage, regulation of hydrological cycles and climate patterns 5-7 . Riverside forests 25 are particularly threatened and suffer losses due to the conversion of forest cover to pastures, 26 compromising the maintenance of water flows 8 . The recovery of degraded areas is necessary to 27 recuperate the standing forest value and the Amazon offers an excellent recovery opportunity due to 28 its natural potential for regeneration 9,10 . Yet, the regrowth rate of degraded Amazon forests can be 29 slow, as abandoned areas are typically on compacted poor quality soils 11,12 and due to the high 30 structural and biological diversity of the original forests 13 . 31Separating the complex interactions driving recruitment and recovery patterns of highly diverse 32 Amazon forests is challenging 2,3,14,15 , yet we know that different faunal groups can modulate and 33 generate key impacts [16][17][18][19] . Indeed, the successional trajectory of natural regeneration in degraded 34 forests ...

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“…There are a total of 8 families who live along the ANF border and a further 23 within 20 km (Norris and Michalski, 2013). It is estimated that 12.5 ha of permanent açaí cultivation would be required to provide the equivalent net present value of commercially valuable timber purchased by a sawmill (Fortini and Carter, 2014).…”

mentioning

confidence: 99%

Too rare for non-timber resource harvest? Meso-scale composition and distribution of arborescent palms in an Amazonian sustainable-use forest

Norris

Chuma

Arévalo-Sandi

et al. 2016

Forest Ecology and Management

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Highlights The occurrence, density and biomass of adult arborescent palms were measured in a National Forest in the eastern Brazilian Amazon. Commercially important arborescent palms were rare. Density and biomass were related to hydrographic and topographic variables. Subsidised agroforestry practices are required to facilitate the commercialization of palm NTFPs. Published as:Norris, D., Chuma, V.J.U.R., Arevalo-Sandi, A.R., Paredes, O.S.L. and Peres, C.A., 2016. Too rare for non-timber resource harvest? Meso-scale composition and distribution of arborescent palms in an Amazonian sustainable-use forest. Forest Ecology and Management, 377,. oleracea, an economically important species. The presence, biomass, and density of palms were uncorrelated with geographic distances among plots. The hydrographic model significantly explained variation in palm presence and biomass, whereas density was only explained by the topographic model. Our findings indicate that arborescent palms are currently too rare to be efficiently harvested as NTFPs in the study area. Yet, comparisons with published estimates suggest that there is significant potential for agroforestry to facilitate the commercialization of palm NTFPs for community based extractive activities.

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Socio-economic and spatial determinants of anthropogenic predation on Yellow-spotted River Turtle, Podocnemis unifilis (Testudines: Pelomedusidae), nests in the Brazilian Amazon: Implications for sustainable conservation and management

Cited by 33 publications

References 23 publications

Nest removal by humans creates an evolutionary trap for Amazonian freshwater turtles

Nest removal by humans creates an evolutionary trap for Amazonian freshwater turtles

Big trees drive forest structure patterns across a lowland Amazon regrowth gradient

Too rare for non-timber resource harvest? Meso-scale composition and distribution of arborescent palms in an Amazonian sustainable-use forest

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