Evaluating effects of deforestation, hunting, and El Niño events on a threatened lemur

Dunham, Arthur E.; Erhart, Elizabeth M.; Overdorff, Deborah J.; Wright, Patricia C.

doi:10.1016/j.biocon.2007.10.006

Cited by 64 publications

(65 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As in a related study (Dunham et al, 2008), fecundity of P. edwardsi was found to be lower when the second 6 months of life coincided with the warmer phases of ENSO (Spearman's P 5 0.55, df 5 19, P 5 0.01); in other words, during El Niñ o years fecundity was significantly lower than non-El Niñ o years (GLM, F 1, 16 5 5.5, Po0.02) (Fig. 3).…”

Section: Overall Fecunditysupporting

confidence: 52%

“…In cases where sex was unknown, parameters were estimated under the assumption of equivalent mortality levels among sexes and a 1 : 1 sex ratio at birth. Like most lemurs, P. edwardsi are sexually monomorphic in size (Dunham & Rudolf, 2009) and a previous study of the same population (Dunham et al, 2008) showed no significant difference in survival to 1 year of age when offspring of known sex were compared (Student's t-test, t 5 0.20, df 5 17, P 5 0.842). We focused on fecundity because population growth rate of this species has been shown to be sensitive to changes in this parameter (Dunham et al, 2008) and it may be the most sensitive parameter to environmental change (King et al, 2005).…”

Section: Demographic Datamentioning

confidence: 79%

“…Generalized linear models of fecundity, and its subcomponents of birth rate and female first year survival, were constructed using Akaike's information criterion (AIC). We focused our environmental variables for the analysis on precipitation patterns during the wet and dry seasons because they are thought to be biologically relevant to the lemurs and are predicted to change with a changing climate (Dunham et al, 2008), as well as ENSO phase and cyclone presence. Variables included in the models were: (1) ENSO phase (based on JMA index), (2) average monthly dry season rainfall ( July-October), (3) months of drought, defined as the number of months of below average dry season rain (o150 mm), (4) average monthly wet season rainfall (January-March), (5) months with extreme rain, defined as the number of months with rainfall 4550 mm (an arbitrary threshold level of rainfall determined as that occurring 10% of an average year) and (6) presence/absence of cyclones during the year.…”

Section: Statistical Analysesmentioning

confidence: 99%

“…Over 80% of the forest cover has already been lost and the populations of many remaining species are small and fragmented (Whitmore, 2000). While there has been much research discussing the effects of habitat loss and hunting pressures on the viability of wildlife populations in Madagascar (Sommer & Hommen, 2001;Irwin et al, 2005;Lehman et al, 2005Lehman et al, , 2006Mittermeier et al, 2006), the confounding effects of recent climate change and global climate cycles such as El Niñ o Southern Oscillations (ENSO) have rarely been broached (Wright, 2006;Raxworthy et al, 2008; but see Dunham et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…In the southeastern rainforest of Madagascar, this strict seasonality results in weaning schedules of diurnal lemurs to coincide with a seasonal peak in fruit and young leaf availability (Wright, 1999(Wright, , 2006, suggesting the potential importance of reproductive timing to infant survival for a whole guild of arboreal primates. We assembled 49 years of data of ENSO cycles and regional rainfall patterns in southeastern Madagascar and synthesized 20 years of demographic data on an endangered lemur of the southeastern rainforests, Propithecus edwardsi (Milne Edwards' sifaka) (Dunham et al, 2008;Erhart & Overdorff, 2008b;Wright, 1995). With these data, we evaluated associations between variables to address the following questions: (1) How are rainfall patterns in southeastern Madagascar associated with ENSO?…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Global climate cycles and cyclones: consequences for rainfall patterns and lemur reproduction in southeastern Madagascar

Dunham

Erhart

Wright

2010

Global Change Biology

Self Cite

107

View full text Add to dashboard Cite

Most studies that examine the influence of climatic change on flora and fauna have focused on northern latitudes; however, there is increasing recognition that tropical regions are also being affected. Despite this, regions such as Madagascar, which are rich in endemic biodiversity but may have low adaptive capacity to climatic change, are poorly represented in studies examining the effects of climate variability on biota. We investigated how El Niñ o Southern Oscillations (ENSO) influence precipitation patterns in the rainforest region of southeastern Madagascar (1962Madagascar ( -2006 and then constructed models to assess the potential contribution of climatic variables on the reproductive parameters of the Milne Edward's sifaka, a threatened lemur species (Propithecus edwardsi), over a 20-year period. The Southern Oscillation Index of sea surface temperature (SST) anomalies in the tropical Pacific was associated with precipitation patterns including wetter wet seasons during warmer phases and drier dry seasons following cooler phases. The bestsupported models of lemur fecundity (female offspring per female that survive to 1 year of age per year) included cyclone presence during gestation and ENSO phase before conception and during the first 6 months of life. Models also suggested that heavy rains during gestation may limit birth rates and that prolonged drought during female lactation may limit first year offspring survival; although these variables were given little importance for predicting overall fecundity relative to ENSO phases and cyclone presence. Our results linking lemur reproduction with climatic variability suggest that climatic changes may be an additional threat to Madagascar's unique and already endangered flora and fauna. The association between precipitation in southeastern Madagascar and SST anomalies in the tropical Pacific suggests that dynamics of wildlife populations even in tropical areas such as Madagascar can be affected by global climate cycles making them potentially vulnerable to global climate change.

show abstract

Section: Overall Fecunditysupporting

confidence: 52%

Section: Demographic Datamentioning

confidence: 79%

Section: Statistical Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Global climate cycles and cyclones: consequences for rainfall patterns and lemur reproduction in southeastern Madagascar

Dunham

Erhart

Wright

2010

Global Change Biology

Self Cite

107

View full text Add to dashboard Cite

show abstract

Influence of environmental conditions on population growth and age‐specific vital rates of a long‐lived primate species in two contrasted habitats

et al. 2023

View full text Add to dashboard Cite

As wildlife is increasingly affected by environmental change, identifying how vital rates vary with ecological factors is essential to predict the consequences of environmental perturbations on wild population dynamics. We explored the effects of habitat constraints on the demographic and life history patterns of two Barbary macaque (Macaca sylvanus) populations living in two contrasted habitats in Algeria. Using 11 years of field data, we estimated age‐specific survival rates of females and of infants of both sexes, as well as female reproduction rates. We investigated how these vital rates were influenced by both intra‐ and inter‐habitat environmental variations. We parameterized age‐structured female‐only transition matrices and conducted a prospective analysis to estimate the contribution of each vital rate to the populations' asymptotic growth rates (λ). A retrospective analysis (LTRE, Life Table Response Experiment) was also conducted to determine how each vital rate contributed to the observed differences in λ between populations. The macaques exhibited common patterns of survival and reproduction (low rates at young ages, and then high and stable until a decrease at old ages), with first evidence of both actuarial and reproductive senescence. Both populations were growing. In both populations, adult and immature survival had the highest elasticities, and remained stable in changing environmental conditions. By contrast, infant survival and female reproduction had low elasticities, and varied more with environmental variations. As Barbary macaque habitats are increasingly degrading, we provide robust estimates of their vital rates with conservation implications, in particular to predict population responses to anthropogenic perturbations.

show abstract

Frugivory in four sympatric lemurs: implications for the future of Madagascar's forests

Wright

Tecot

Erhart

et al. 2011

American J Primatol

Self Cite

View full text Add to dashboard Cite

Although some conservationists accept that not all species can be saved, we illustrate the difficulty in deciding which species are dispensable. In this article, we examine the possibility that the integrity of a forest relies on its entire faunal assemblage. In Madagascar, one faunal group, the lemurs, accounts for the greatest biomass and species richness among frugivores. For example, 7 of the 13 sympatric lemur species in Madagascar's eastern rainforests consume primarily fruit. Because of this, we suggest that some tree species may rely heavily on particular lemur taxa for both seed dispersal and germination. In Ranomafana National Park, the diets for four of the day-active lemur frugivores have been documented during annual cycles over a 5-year period. We predicted that, although the fruit of some plant taxa would be exploited by multiple lemur species, the fruit of others would be eaten by one lemur species alone. Analyses reveal that while lemurs overlap in a number of fruit taxa exploited, 46% (16/35) of families and 56% (29/52) of genera are eaten exclusively by one lemur species. We, therefore, predict local changes in forest composition and structure if certain of these lemur species are eliminated from a forest owing to hunting, disease, or habitat disturbance. We also suggest that this result may be of global significance because carbon sequestration by the tropical forests in Madagascar may be reduced as a result of this predicted change in forest composition.

show abstract

Evaluating effects of deforestation, hunting, and El Niño events on a threatened lemur

Cited by 64 publications

References 31 publications

Global climate cycles and cyclones: consequences for rainfall patterns and lemur reproduction in southeastern Madagascar

Global climate cycles and cyclones: consequences for rainfall patterns and lemur reproduction in southeastern Madagascar

Influence of environmental conditions on population growth and age‐specific vital rates of a long‐lived primate species in two contrasted habitats

Frugivory in four sympatric lemurs: implications for the future of Madagascar's forests

Contact Info

Product

Resources

About