Mitchell Irwin
Biographic Data
| ID | 5208630 |
|---|---|
| NAME | Mitchell Irwin |
| GIVEN NAMES | Mitchell |
| FAMILY NAME | Irwin |
| SIGNATURE | IRWIN M |
| AFFILIATIONS | Northern Illinois University |
| ORCID | 0000-0003-2088-0028 |
| VERIFIED | Yes |
| TOTAL WORKS | 21 |
| TOTAL CITATIONS | 75 |
| AUTHOR COUNT | 21 |
| EDITOR COUNT | 0 |
| FIRST PUBLICATION YEAR | 2004 |
| LATEST PUBLICATION YEAR | 2026 |
| H-INDEX | 4 |
Contrasting Nutritional Intakes in Sympatric Malagasy Lemurs: Re‐Examining Frugivore and Folivore Strategies and Outcomes Using the “Efficiency‐Velocity” Continuum and Use of Secondary Foods
Importance of Plant Galls to the Diet and Nutrition of a Frugivorous Primate, Varecia variegata
Frugivorous primates may consume unusual food items, such as plant galls, to meet their nutritional requirements; yet, the contributions of these dietary components to their diet, nutrition requirements, and energy intakes are still unclear. We documented the importance of plant galls in these aspects for black‐and‐white ruffed lemurs ( Varecia variegata ) in a Malagasy rainforest. Using daily observation data of lemur foraging and nutritional an…
Dietary and Nutritional Selections by Ecologically Diverse Lemurs in Nonnative Forests
Activity budget and seasonal activity shifts in sympatric lemurs: Increased lean season effort in a cathemeral frugivore contrasts with energy conservation in a diurnal folivore
One of the most fundamental aspects of a species’ behavioral strategy is its activity budget; for primates this generally involves the allocation of available time among resting, feeding, traveling, and social behavior. Comparisons between species, populations, or individuals can reveal divergences in adaptive strategies and current stressors, and reflect responses to such diverse pressures as predation, thermoregulation, nutrition, and social ne…
Melanism in a Wild Sifaka Population: Darker Where Cold and Fragmented
Condensed tannins in the diet of folivorous diademed sifakas and the gap between crude and available protein
Tannins, a type of plant secondary metabolite, are well‐known for their ability to precipitate proteins and thereby reduce the protein available to consumers. Most primate studies have focused on condensed tannins (CTs) as they were thought to be the most effective type of tannin at preventing protein acquisition, but there is growing recognition that other types of tannins can bind to proteins, suggesting the division among tannin types is not a…
Fermented food consumption in wild nonhuman primates and its ecological drivers
OBJECTIVES: Although fermented food use is ubiquitous in humans, the ecological and evolutionary factors contributing to its emergence are unclear. Here we investigated the ecological contexts surrounding the consumption of fruits in the late stages of fermentation by wild primates to provide insight into its adaptive function. We hypothesized that climate, socioecological traits, and habitat patch size would influence the occurrence of this beha…
Competition for dead trees between humans and aye-ayes (Daubentonia madagascariensis) in central eastern Madagascar
The importance of protein in leaf selection of folivorous primates
Protein limitation has been considered a key factor in hypotheses on the evolution of life history and animal communities, suggesting that animals should prioritize protein in their food choice. This contrasts with the limited support that food selection studies have provided for such a priority in nonhuman primates, particularly for folivores. Here, we suggest that this discrepancy can be resolved if folivores only need to select for high protei…
Minerals in the foods and diet of diademed sifakas: Are they nutritional challenges
Minerals, though needed in small quantities, are essential to metabolic processes, and deficiencies can seriously threaten health, reproduction and survival. Despite this, few studies have measured mineral composition of wild primate foods and fewer have quantified mineral intake. Here we measured the concentration of nine minerals in 75 foods of diademed sifakas (Propithecus diadema; five groups) in habitats with varying levels of disturbance at…
Primate genotyping via high resolution melt analysis: Rapid and reliable identification of color vision status in wild lemurs
Averting Lemur Extinctions amid Madagascar's Political Crisis
Community-based management, ecotourism, and researchers' presence are proposed to prevent lemur extinctions.
Nutritional correlates of the “lean season”: Effects of seasonality and frugivory on the nutritional ecology of diademed sifakas
Primate field studies often identify “lean seasons,” when preferred foods are scarce, and lower‐quality, abundant foods (fallback foods) are consumed. Here, we quantify the nutritional implications of these terms for two diademed sifaka groups ( Propithecus diadema ) in Madagascar, using detailed feeding observations and chemical analyses of foods. In particular, we sought to understand 1) how macronutrient and energy intakes vary seasonally, inc…
A glance to the past: Subfossils, stable isotopes, seed dispersal, and lemur species loss in Southern Madagascar
The Spiny Thicket Ecoregion (STE) of Southern and southwestern Madagascar was recently home to numerous giant lemurs and other “megafauna,” including pygmy hippopotamuses, giant tortoises, elephant birds, and large euplerid carnivores. Following the arrival of humans more than 2,000 years ago, dramatic extinctions occurred. Only one‐third of the lemur species which earlier occupied the STE survive today; other taxa suffered even greater losses. W…
Variation in physiological health of diademed sifakas across intact and fragmented forest at Tsinjoarivo, eastern Madagascar
As undisturbed habitat becomes increasingly rare, managers charged with ensuring the survival of endangered primate species must increasingly utilize disturbed and degraded habitats in species survival plans. Yet we have an imperfect understanding of the true long‐term viability of primate populations in disturbed habitat, and census data can be misleading because density is not necessarily correlated with habitat quality and population viability…
Does Eulemur cinereiceps exist? Preliminary evidence from genetics and ground surveys in southeastern Madagascar
Although appearing in the literature as early as 1890, the brown lemur form Eulemur cinereiceps has recently resurfaced as a potentially valid taxon, distinct from neighboring, presumably closely related species such as white‐collared lemurs ( Eulemur albocollaris ). We propose two scenarios for the potential separation of E. cinereiceps and E. albocollaris : (1) coastal and interior populations represent two distinct taxa and (2) the coastal pop…
Feeding Ecology of Propithecus diadema in Forest Fragments and Continuous Forest
Diademed sifakas ( Propithecus diadema ) use olfaction to forage for the inflorescences of subterranean parasitic plants (Balanophoraceae: (Langsdorffia sp., and Cytinaceae: Cytinus sp.)
Primates usually locate food resources using visual cues and memory, yet the potential for olfactory‐guided (or olfactory‐assisted) food location remains relatively unexplored. Here we report observations of wild Propithecus diadema that strongly suggest that olfaction is used to locate the inflorescences of two subterranean parasitic plant species ( Langsdorffia sp. and Cytinus sp.). These valued but seasonal food resources are found obscured in…
Living in forest fragments reduces group cohesion in diademed sifakas ( Propithecus diadema ) in eastern Madagascar by reducing food patch size
Forest fragmentation is thought to threaten primate populations, yet the mechanisms by which this occurs remain largely unknown. However, fragmentation is known to cause dietary shifts in several primate species, and links between food resource distribution and within‐group spatial dynamics are well documented. Thus, fragmentation has the potential to indirectly affect spatial dynamics, and these changes may present additional stresses to fragmen…
A broad view of evolution: A symposium in honor of George Williams
Ontogenetic correlates of diet in Malagasy lemurs
There is a well-documented relationship between development and other life-history parameters among anthropoid primates. Smaller-bodied anthropoids tend to mature more rapidly than do larger-bodied species. Among anthropoids of similar body sizes, folivorous species tend to grow and mature more quickly than do frugivorous species, thus attaining adult body size at an earlier age. This pattern conforms to the expectations of Janson and van Schaik'…
Ontogenetic correlates of diet in Malagasy lemurs
There is a well-documented relationship between development and other life-history parameters among anthropoid primates. Smaller-bodied anthropoids tend to mature more rapidly than do larger-bodied species. Among anthropoids of similar body sizes, folivorous species tend to grow and mature more quickly than do frugivorous species, thus attaining adult body size at an earlier age. This pattern conforms to the expectations of Janson and van Schaik'…
Feeding Ecology of Propithecus diadema in Forest Fragments and Continuous Forest
Nutritional correlates of the “lean season”: Effects of seasonality and frugivory on the nutritional ecology of diademed sifakas
Primate field studies often identify “lean seasons,” when preferred foods are scarce, and lower‐quality, abundant foods (fallback foods) are consumed. Here, we quantify the nutritional implications of these terms for two diademed sifaka groups ( Propithecus diadema ) in Madagascar, using detailed feeding observations and chemical analyses of foods. In particular, we sought to understand 1) how macronutrient and energy intakes vary seasonally, inc…
Fermented food consumption in wild nonhuman primates and its ecological drivers
OBJECTIVES: Although fermented food use is ubiquitous in humans, the ecological and evolutionary factors contributing to its emergence are unclear. Here we investigated the ecological contexts surrounding the consumption of fruits in the late stages of fermentation by wild primates to provide insight into its adaptive function. We hypothesized that climate, socioecological traits, and habitat patch size would influence the occurrence of this beha…
A broad view of evolution: A symposium in honor of George Williams
Ontogenetic correlates of diet in Malagasy lemurs
There is a well-documented relationship between development and other life-history parameters among anthropoid primates. Smaller-bodied anthropoids tend to mature more rapidly than do larger-bodied species. Among anthropoids of similar body sizes, folivorous species tend to grow and mature more quickly than do frugivorous species, thus attaining adult body size at an earlier age. This pattern conforms to the expectations of Janson and van Schaik'…
Diademed sifakas ( Propithecus diadema ) use olfaction to forage for the inflorescences of subterranean parasitic plants (Balanophoraceae: (Langsdorffia sp., and Cytinaceae: Cytinus sp.)
Primates usually locate food resources using visual cues and memory, yet the potential for olfactory‐guided (or olfactory‐assisted) food location remains relatively unexplored. Here we report observations of wild Propithecus diadema that strongly suggest that olfaction is used to locate the inflorescences of two subterranean parasitic plant species ( Langsdorffia sp. and Cytinus sp.). These valued but seasonal food resources are found obscured in…
Living in forest fragments reduces group cohesion in diademed sifakas ( Propithecus diadema ) in eastern Madagascar by reducing food patch size
Forest fragmentation is thought to threaten primate populations, yet the mechanisms by which this occurs remain largely unknown. However, fragmentation is known to cause dietary shifts in several primate species, and links between food resource distribution and within‐group spatial dynamics are well documented. Thus, fragmentation has the potential to indirectly affect spatial dynamics, and these changes may present additional stresses to fragmen…
Does Eulemur cinereiceps exist? Preliminary evidence from genetics and ground surveys in southeastern Madagascar
Although appearing in the literature as early as 1890, the brown lemur form Eulemur cinereiceps has recently resurfaced as a potentially valid taxon, distinct from neighboring, presumably closely related species such as white‐collared lemurs ( Eulemur albocollaris ). We propose two scenarios for the potential separation of E. cinereiceps and E. albocollaris : (1) coastal and interior populations represent two distinct taxa and (2) the coastal pop…
Feeding Ecology of Propithecus diadema in Forest Fragments and Continuous Forest
Variation in physiological health of diademed sifakas across intact and fragmented forest at Tsinjoarivo, eastern Madagascar
As undisturbed habitat becomes increasingly rare, managers charged with ensuring the survival of endangered primate species must increasingly utilize disturbed and degraded habitats in species survival plans. Yet we have an imperfect understanding of the true long‐term viability of primate populations in disturbed habitat, and census data can be misleading because density is not necessarily correlated with habitat quality and population viability…
A glance to the past: Subfossils, stable isotopes, seed dispersal, and lemur species loss in Southern Madagascar
The Spiny Thicket Ecoregion (STE) of Southern and southwestern Madagascar was recently home to numerous giant lemurs and other “megafauna,” including pygmy hippopotamuses, giant tortoises, elephant birds, and large euplerid carnivores. Following the arrival of humans more than 2,000 years ago, dramatic extinctions occurred. Only one‐third of the lemur species which earlier occupied the STE survive today; other taxa suffered even greater losses. W…
Averting Lemur Extinctions amid Madagascar's Political Crisis
Community-based management, ecotourism, and researchers' presence are proposed to prevent lemur extinctions.
Nutritional correlates of the “lean season”: Effects of seasonality and frugivory on the nutritional ecology of diademed sifakas
Primate field studies often identify “lean seasons,” when preferred foods are scarce, and lower‐quality, abundant foods (fallback foods) are consumed. Here, we quantify the nutritional implications of these terms for two diademed sifaka groups ( Propithecus diadema ) in Madagascar, using detailed feeding observations and chemical analyses of foods. In particular, we sought to understand 1) how macronutrient and energy intakes vary seasonally, inc…
Primate genotyping via high resolution melt analysis: Rapid and reliable identification of color vision status in wild lemurs
Competition for dead trees between humans and aye-ayes (Daubentonia madagascariensis) in central eastern Madagascar
The importance of protein in leaf selection of folivorous primates
Protein limitation has been considered a key factor in hypotheses on the evolution of life history and animal communities, suggesting that animals should prioritize protein in their food choice. This contrasts with the limited support that food selection studies have provided for such a priority in nonhuman primates, particularly for folivores. Here, we suggest that this discrepancy can be resolved if folivores only need to select for high protei…
Minerals in the foods and diet of diademed sifakas: Are they nutritional challenges
Minerals, though needed in small quantities, are essential to metabolic processes, and deficiencies can seriously threaten health, reproduction and survival. Despite this, few studies have measured mineral composition of wild primate foods and fewer have quantified mineral intake. Here we measured the concentration of nine minerals in 75 foods of diademed sifakas (Propithecus diadema; five groups) in habitats with varying levels of disturbance at…
Condensed tannins in the diet of folivorous diademed sifakas and the gap between crude and available protein
Tannins, a type of plant secondary metabolite, are well‐known for their ability to precipitate proteins and thereby reduce the protein available to consumers. Most primate studies have focused on condensed tannins (CTs) as they were thought to be the most effective type of tannin at preventing protein acquisition, but there is growing recognition that other types of tannins can bind to proteins, suggesting the division among tannin types is not a…
Fermented food consumption in wild nonhuman primates and its ecological drivers
OBJECTIVES: Although fermented food use is ubiquitous in humans, the ecological and evolutionary factors contributing to its emergence are unclear. Here we investigated the ecological contexts surrounding the consumption of fruits in the late stages of fermentation by wild primates to provide insight into its adaptive function. We hypothesized that climate, socioecological traits, and habitat patch size would influence the occurrence of this beha…
Activity budget and seasonal activity shifts in sympatric lemurs: Increased lean season effort in a cathemeral frugivore contrasts with energy conservation in a diurnal folivore
One of the most fundamental aspects of a species’ behavioral strategy is its activity budget; for primates this generally involves the allocation of available time among resting, feeding, traveling, and social behavior. Comparisons between species, populations, or individuals can reveal divergences in adaptive strategies and current stressors, and reflect responses to such diverse pressures as predation, thermoregulation, nutrition, and social ne…
Melanism in a Wild Sifaka Population: Darker Where Cold and Fragmented
Dietary and Nutritional Selections by Ecologically Diverse Lemurs in Nonnative Forests
Importance of Plant Galls to the Diet and Nutrition of a Frugivorous Primate, Varecia variegata
Frugivorous primates may consume unusual food items, such as plant galls, to meet their nutritional requirements; yet, the contributions of these dietary components to their diet, nutrition requirements, and energy intakes are still unclear. We documented the importance of plant galls in these aspects for black‐and‐white ruffed lemurs ( Varecia variegata ) in a Malagasy rainforest. Using daily observation data of lemur foraging and nutritional an…
Contrasting Nutritional Intakes in Sympatric Malagasy Lemurs: Re‐Examining Frugivore and Folivore Strategies and Outcomes Using the “Efficiency‐Velocity” Continuum and Use of Secondary Foods
Biology (19 works) · Primate Behavior and Ecology (18 works) · Ecology (16 works) · Primate (13 works) · Lemur (12 works) · Amphibian and Reptile Biology (10 works) · Habitat (9 works) · Zoology (8 works) · Frugivore (7 works) · Wildlife Ecology and Conservation (7 works)