Dietary strategies of Old World Fruit Bats (Megachiroptera,Pteropodidae): how do they obtain sufficient protein?

The complexity of dietary strategies evolved by megachiropterans (Pteropodidae) is gaining recognition, although there are relatively few reports of feeding habits other than frugivory, and even fewer of non-herbivorous ones. This paper reviews the information obtained so far on how the diets of Old World fruit bats may provide them with sufficient protein, as most fruits are known to be low in this vital nutrient. There is evidence to suggest that pollen, leaves or insects may provide wild pteropodids with the extra protein that studies in captivity have shown to be necessary.     

Fruit consumption by carnivores in Mediterranean Europe

• 1 We reviewed patterns of fruit consumption amongst 10 species of mesocarnivores: red fox Vulpes vulpes, weasel Mustela nivalis, stoat Mustela erminea, polecat Mustela putorius, stone marten Martes foina, pine marten Martes martes, Eurasian badger Meles meles, common genet Genetta genetta, Egyptian mongoose Herpestes ichneumon and wildcat Felis silvestris in Mediterranean Europe.
• 2 The 65 reviewed studies recorded 79 different fruits eaten by carnivores, 58 of which were identified to species. Most records (63%) were of fleshy fruits with high pulp content. The frequency of occurrence of fruit items varied widely amongst species and regions. Four of the carnivore species (red fox, stone marten, badger and common genet) included more than 30 fruit species in their diet.
• 3 A longitudinal pattern was detected in the consumption of fruit in the Mediterranean region, with the frequency of occurrence of fruit consumption increasing towards the east.

     

Insect-eating by sympatric Lowland gorillas (Gorilla g. gorilla) and chimpanzees (Pan t. troglodytes) in the Lopé Reserve,Gabon

Sympatric populations of lowland gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes troglodytes) in the Lopé Reserve in central Gabon consumed insects at similar average frequencies over a 7-year period (30% versus 31% feces contained insect remains). Data came mostly from fecal analysis supplemented by observation and trail evidence. The weaver ant (Oecophylla longinoda) was the species eaten most frequently by both gorillas and chimpanzees. Other species of insects wore eaten but there was virtually no overlap: Chimpanzees used tools to eat Apis bees (and their honey) and two large species of ants; gorillas ate three species of small ants. Thus, despite their shared habitat, the esources utilized were not identical as gorillas do not show the tool-use “technology” of chimpanzees. The frequency of insect-eating by both species of ape varied seasonally and between years but in different ways. This variation did not seem to be related to the ratio of fruit to foliage in their diets. Gorillas of all age-classes ate insects at similar rates. Comparisons with insectivory by other populations of gorillas indicate differences exist. Mountain gorillas (Gorilla g. beringei) in the Virunga Volcanoes, Rwanda, consume thousands of invertebrates daily, eating them inadvertently with handfuls of herbaceous foods but they deliberately ingest insect-foods only rarely. Lowland gorillas at Lopé habitually ate social insects, and their selective processing of herbaceous foods probably minimizes inadvertent consumption of other invertebrates. Gorillas at Belinga in northeastern Gabon, 250 km from Lop6, ate social insects at similar rates but ignored weaver ants in favor of Cubitermes sulcifrons, a small species of termite that occurs at Lopé but was not eaten by gorillas. This indicates that local traditions similar to those reported for chimpanzees also exist amongst populations of gorillas. © 1992 Wiley-Liss, Inc.     

Arthropod remains in the oral cavities of fossil reptiles support inference of early insectivory

Inference of feeding preferences in fossil terrestrial vertebrates (tetrapods) has been drawn predominantly from craniodental morphology, and less so from fossil specimens preserving conclusive evidence of diet in the form of oral and/or gut contents. Recently, the pivotal role of insectivory in tetrapod evolution was emphasized by the identification of putative insectivores as the closest relatives of the oldest known herbivorous amniotes. We provide the first compelling evidence for insectivory among early tetrapods on the basis of two 280-million-year-old (late Palaeozoic) fossil specimens of a new species of acleistorhinid parareptile with preserved arthropod cuticle on their toothed palates. Their dental morphology, consisting of homodont marginal dentition with cutting edges and slightly recurved tips, is consistent with an insectivorous diet. The intimate association of arthropod cuticle with the oral region of two small reptiles, from a rich fossil locality that has otherwise not produced invertebrate remains, strongly supports the inference of insectivory in the reptiles. These fossils lend additional support to the hypothesis that the origins and earliest stages of higher vertebrate evolution are associated with relatively small terrestrial insectivores.     

Diet of Alouatta belzebul discolor in an Amazonian Rain Forest of Northern Mato Grosso State, Brazil

Prior field studies of Alouatta showed the highest frugivory in A. belzebul. During 10 mo between October 1999 and October 2000, we studied the feeding ecology of a group of 7–9 red-handed howlers (Alouatta belzebul discolor) in a primary forest on the banks of a tributary of the Teles Pires River, near Paranaíta, MT, Brazil (9°34S; 56°19W). The howlers used 3 types of habitat: upland (terra firme) forest, flood plain forest (igapó) and palm forest (açaizal). During 45 complete days of observation, the group fed on 67 plant species (N = 2039 feeding records) in 24 families. The 2 most used families were Leguminosae and Moraceae, with 17 species each. Fruits predominated (40–80%) in every month, except June, when young leaves accounted for 54% of the diet. Dialium guianense (Leguminosal, Caesalpinioideae) was the most consumed species. Flower (6%) and mature leaf (5%) consumptions were low. Tree bark, live and decayed wood, and woody twig monthly consumption varied from 0 to 26%, and occurred only in igapó, where they used mostly Macrolobium acaciaefolium (Leguminosae, Caesalpinioideae), Clitoria amazonum (Leguminosae, Papilionoideae) and Licania cf. canescens (Chrysobalanaceae). Our study on Alouatta belzebul discolor complements the high frugivory in A. b. belzebul and documents uncommon dietary items for the species. Although there is intraspecific variation in howler diets and new studies have shown higher frugivory for more folivorous species, Alouatta belzebul seems to be the most frugivorous howler species, in spite of its wide geographical distribution and, in this case, sympatry with Ateles chamek, a frugivore.     

Sources of Assimilated Proteins in Old and New World Phytophagous Bats

Dietary proteins are considered crucial for growth and maintenance in mammals, but many fruit‐eating mammals feed largely on a protein‐poor diet. In the Chiroptera, frugivory has evolved twice, in the Old World Pteropodidae and in the New World Phyllostomidae, especially the Stenodermatinae. Recent studies based on the analysis of nitrogen isotope ratios (δ¹⁵N) suggest that phyllostomids feed to varying degrees on arthropods to meet their nitrogen (N) requirements. Arthropod feeding has rarely been observed in Pteropodidae. Thus, we asked whether pteropodids meet their N requirements by feeding exclusively on plant matter. We predicted that tissue from pteropodid wing membranes should be depleted in ¹⁵N relative to those of obligate insectivorous rhinolophoid, vespertilionid or emballonurid bats, if pteropodids acquire proteins exclusively from fruits, leaves or nectar. We found that δ¹⁵N in pteropodids were significantly lower than in obligate insectivorous bats. In addition, mean δ¹⁵N of Old World pteropodids was similar to that of obligate frugivorous stenodermatines of the New World tropics. We infer from these data that pteropodids are predominantly phytophagous bats. From a nutritional perspective, pteropodids and stenodermatines are very similar, suggesting that they share convergent physiological adaptations to compensate for the lack of dietary nitrogen.     

Morphological relationships of passerine birds from Australia and New Guinea in relation to their diets

Beak, wing, leg and intestinal lengths, and gizzard widths, were all significantly related to body mass in 51 honeyeater species from Australia, 48 honeyeater species from New Guinea and 31 purely insectivorous passerine bird species from Australia. The nectar-feeding honeyeaters had smaller gizzards and intestines than wholly insectivorous birds of comparable size, although their wing and leg lengths did not differ; New Guinean and Australian honeyeaters were similar in these respects. Overall, honeyeaters had longer beaks than pure insectivores. Among Australian honeyeaters, those genera consuming more nectar than insects had longer beaks than the less nectarivorous, more insectivorous genera. Indeed, the latter group had beaks comparable in length to wholly insectivorous birds. All morphological differences revealed were attributable to known differences in diet.