Determinants of isotopic variation in two sympatric mouse lemur species from northwestern Madagascar

Heck, Laura; Crowley, Brooke E.; Thorén, Sandra; Radespiel, Ute

doi:10.1017/cbo9781139871822.015

Cited by 6 publications

(7 citation statements)

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“…½″ diameter; 12–40 mg) from each lemur’s hip, thigh, tail base, or side of torso on a bi-monthly basis starting in February 2017 and ending in March 2018 (eight shaves total, see Table 2 ). I focused on the base of the tail region because it is where I have previously sampled fur for isotopic research [ 25 , 26 , 27 ], and is not typically chewed or groomed. Following each shave, regrowth was measured on a bi-weekly basis using calipers (study subjects were handled as described above).…”

Section: Methodsmentioning

confidence: 99%

“…First, cheirogaleids exhibit the most pronounced seasonal metabolic changes of any primate [ 22 ], and thus are well-suited for examining potential seasonal fluctuations in fur growth. Second, both genera (but particularly mouse lemurs) have been the study subjects of both isotopic and hormonal research over the past decade, e.g., [ 23 , 24 , 25 , 26 , 27 , 28 ]. Researchers have typically assumed constant fur growth, and estimated growth rates based on ad-hoc observations in the field, e.g., [ 4 ], or data for murid rodents, e.g., [ 26 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

“…However, as noted by Rakotoniaina and colleagues [ 4 ]: “At present, the lack of precise information on hair growth rate in M. murinus limits our estimation about the period of accumulation of cortisol recorded with the hair sample”. Given the growing interest in investigating seasonal trends in diet, e.g., [ 23 , 26 , 27 ], monitoring seasonal variability in stress hormones, e.g., [ 4 ], and using cheirogaleids as proxies for tracking baseline isotopic differences among habitats in Madagascar, e.g., [ 24 , 25 ], establishing how their fur grows is both necessary and timely.…”

Section: Introductionmentioning

confidence: 99%

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Captive Dwarf and Mouse Lemurs Have Variable Fur Growth

Crowley

2020

Animals

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Researchers typically assume constant fur and hair growth for primates, but the few studies that have investigated growth explicitly suggest this may not be the case. Instead, growth may vary considerably among individuals and across seasons. One might expect this variability to be most pronounced for species that have seasonally variable activity patterns (e.g., Madagascar’s Cheiorogaleidae). In particular, dwarf lemurs (Cheirogaleus spp.) undergo considerable changes in their daily activity levels (torpor) in the austral fall, when nights get shorter. I monitored regrowth of shaved fur patches for eight adult captive fat-tailed dwarf lemurs (Cheirogaleus medius) and gray mouse lemurs (Microcebusmurinus) on a bi-weekly basis for 21 months in total. Regrowth varied considerably both within and among individuals. Overall, fur regrew in spurts and was faster for mouse lemurs (0–14 to 215–229 days) than dwarf lemurs (27–40 to 313–327 days). There were significant differences between species and an obvious influence of season for dwarf lemurs, but no clear influence of shave location, age, or sex. Similar trends have been previously reported for captive lemurids, suggesting that seasonal fur growth may be widespread across Lemuroidea. Researchers are cautioned against using primate fur or hair to investigate variables confounded by seasonality (such as diet and body condition) until patterns of growth are better understood.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Captive Dwarf and Mouse Lemurs Have Variable Fur Growth

Crowley

2020

Animals

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“…Specifically, values are highest in the xerophytic spiny thicket in SW Madagascar and lowest in the humid forests in the east and north. There can also be pronounced differences among microhabitats in the same region (Crowley et al, 2012(Crowley et al, , 2014Heck et al, 2016). Plants and animals living on saline coastal soils that are influenced by marine-derived nitrates may also have higher δ 15 N values than those that live inland (Heaton, 1987;Sparks and Crowley, 2018;Mosher et al, 2020;Hixon et al, submitted).…”

Section: Introductionmentioning

confidence: 99%

Ecological Consequences of a Millennium of Introduced Dogs on Madagascar

et al. 2021

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Introduced predators currently threaten endemic animals on Madagascar through predation, facilitation of human-led hunts, competition, and disease transmission, but the antiquity and past consequences of these introductions are poorly known. We use directly radiocarbon dated bones of introduced dogs (Canis familiaris) to test whether dogs could have aided human-led hunts of the island’s extinct megafauna. We compare carbon and nitrogen isotope data from the bone collagen of dogs and endemic “fosa” (Cryptoprocta spp.) in central and southwestern Madagascar to test for competition between introduced and endemic predators. The distinct isotopic niches of dogs and fosa suggest that any past antagonistic relationship between these predators did not follow from predation or competition for shared prey. Radiocarbon dates confirm that dogs have been present on Madagascar for over a millennium and suggest that they at least briefly co-occurred with the island’s extinct megafauna, which included giant lemurs, elephant birds, and pygmy hippopotamuses. Today, dogs share a mutualism with pastoralists who also occasionally hunt endemic vertebrates, and similar behavior is reflected in deposits at several Malagasy paleontological sites that contain dog and livestock bones along with butchered bones of extinct megafauna and extant lemurs. Dogs on Madagascar have had a wide range of diets during the past millennium, but relatively high stable carbon isotope values suggest few individuals relied primarily on forest bushmeat. Our newly generated data suggest that dogs were part of a suite of animal introductions beginning over a millennium ago that coincided with widespread landscape transformation and megafaunal extinction.

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“…The escalating frequency and size of dry season fires poses a serious threat to plant and animal habitats in our study area, eliciting deep concern among the managers of Ankarafantsika National Park. This issue also reverberates with the local communities, especially those in Ambodimanga village, who are legally allowed to use community forest zone within the park and rely on its ecosystem services for their livelihood and well-being [27,35]. Our study is the first to show quantitatively that extensive forest fire in this area is a recent phenomenon in the last five years.…”

Section: Discussionmentioning

confidence: 78%

Non fire-adapted dry forest of Northwestern Madagascar: escalating and devastating trends revealed by remote-sensing data

Percival,

Sato,

Razanaparany

et al. 2023

Preprint

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Ankarafantsika National Park (ANP), the last significant remnant of Northwestern Madagascar's tropical dry forests, is facing rapid degradation due to increased incidences of fire. This poses severe threats to biodiversity, local livelihoods, and vital ecosystem services. Our study, conducted on 3052 ha of ANP's pristine forests, employed advanced remote-sensing techniques to assess fire impacts during the past 37 years. Our aims were to understand historical fire patterns and evaluate forest recovery and susceptibility to repeated fires following initial burns. Using data from multiple Landsat satellite sensors, we constructed a time series of fire events since 1985, which revealed no fire activity before 2014. The Global Ecosystem Dynamics Investigation (GEDI) lidar sensor data were used to observe forest structure in both post-fire areas and undisturbed zones for comparison. We recorded six fire incidents from 2014-2021, during which the fire-affected area exponentially grew. A significant fire incident in October 2021 impacted 1052 hectares, 59% of which had experienced at least one fire in 2-4 years prior, with 60% experiencing 2 preceding incidents: one in 2017 and another in 2019. The initial fire drastically reduced plant cover and tree height, with subsequent fires causing minor additional loss. Post-fire recovery was negligible within the initial four years, even in patches without recurrent fires. The likelihood for an initial burn to trigger subsequent fires within a few years was high, leading to larger, more severe fires. We conclude that ANP's dry forests exhibit high vulnerability and low resilience to anthropogenic fires. Prompt preventive measures are essential to halt further fire spread and conserve the park's unique and invaluable biodiversity.

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Determinants of isotopic variation in two sympatric mouse lemur species from northwestern Madagascar

Cited by 6 publications

References 70 publications

Captive Dwarf and Mouse Lemurs Have Variable Fur Growth

Captive Dwarf and Mouse Lemurs Have Variable Fur Growth

Ecological Consequences of a Millennium of Introduced Dogs on Madagascar

Non fire-adapted dry forest of Northwestern Madagascar: escalating and devastating trends revealed by remote-sensing data

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