Hand-raising a philippine tarsier,Tarsius syrichta

An infant female tarsier (Tarsius syrichta) weighing 20 g at birth was removed for hand-raising at 1 day of age. The infant was maintained in an incubator (32°C, 80% humidity), and fed every 2–3 hours for the first 10 days of life. The infant received a varied formula for the first 4 days. Esbilac (3.3–8.0 cc daily) was given for days 5–10. From days 11 to 67 the infant was fed 6.5–8.0 cc of formula seven times daily. A liver fortified formula was introduced on day 53. Birthweight doubled by day 41 and tripled by day 101. The animals first successful jump was observed at day 25. On day 68 she captured and ate her first live prey. Introduction to adult tarsiers began on day 60. This is the first successful hand-raising of any species of tarsier, which is a genus that reproduces poorly in captivity.     

Predation on a wild Philippine tarsier (Tarsius syrichta)

Little is known about predation on the Philippine tarsier. Only one other case of predation, probably by a cat, has previously been reported. In our study, we present two events of predation, one on a female tarsier by a water monitor lizard, another on an infant tarsier by an unknown predator. We also describe the behaviour of the tarsier mother after losing her infant. Our observations extend current knowledge about predation pressure on the Philippine tarsier.     

Allocare in a nocturnal primate: data on the spectral tarsier, Tarsius spectrum

Non-maternal infant care in many of the small-bodied New World primate species has been hypothesized by some researchers to be related to the high infant/adult weight ratio found in these species. The spectral tarsier, Tarsius spectrum, an Old World primate, has one of the highest infant/adult weight ratios of any primate, with infants weighing between 20-33% of adult weight at birth. On the basis of the hypothesized relationship between allocare and the infant/adult weight ratio, it is predicted that the spectral tarsier will also exhibit extensive allocaretaking behaviour. The results of this study indicate that although spectral tarsiers show care by male and female subadults as well as adult males, it is extremely limited compared to the extensive allocaretaking behavior observed in New World primate species such as Aotus and Callicebus. Spectral tarsier subadult females provide substantially more allocare to infants than do subadult males or adult males. Female subadults were observed sharing food, transporting, grooming, playing, alarm calling, baby-sitting and maintaining physical contact with infants more than other age/sex classes. Although the amount of allocare exhibited by adult males and subadult males was much less than that exhibited by female subadults, the data suggest that adult and subadult male spectral tarsiers do play a small part in the care and socialization of the infant. Adult males and subadult males were both observed occasionally engaging in allocaretaking behaviors such as grooming and playing, as well as frequently patrolling and defending the territory's boundaries. The results from this study suggest that although a high infant/adult weight ratio may be a prerequisite for selection to favor extensive allocare, it is not a causal factor. Additional research is needed in order to understand better the selective pressures involved and the costs and benefits of providing allocare to subadults and adult male spectral tarsiers.     

Positional behavior and social organization of the philippine tarsier (Tarsius syrichta)

This study provides preliminary data on the positional behavior and habitat use of the Philippine tarsier,Tarsius syrichta, which was studied in its natural habitat on the island of Leyte. The locomotor behavior ofT. syrichta is quite comparable to the other species of tarsiers but frequency of use of different postures and support types does seem to distinguish this species from the others.Tarsius bancanus appears to be the most specialized, using vertical clinging postures the most frequently and sitting the least;Tarsius dianae uses vertical clinging the least frequently and sitting the most, andT. syrichta is intermediate. The Philippine tarsier has a small home range similar to that ofT. spectrum. On the other hand, this species likely does not have the small family groups typical of Sulawesi tarsiers but instead uses a noyau system likeT. bancanus. This data supports some apsects ofNiemitz’s (1977) model of anatomical and behavioral specialization among tarsier species.     

Population survey of the Philippine tarsier (Tarsius syrichta) in Corella, Bohol

In 1986, in response to the rapid habitat destruction throughout the archipelago, the Philippine tarsier was classified as endangered. Since that time, this tarsier has been reclassified as data deficient and more recently as near threatened despite a significant lack of information on the population density of the species. Data were collected at the Philippine Tarsier Foundation Sanctuary from June to October 2010. Population density was estimated using a modified form of the quadrat census method. A total of 55 individuals were located within the sampled area. This is equivalent to approximately 1.55 tarsiers per hectare. Ecologically, there were significantly more tarsiers found in the young secondary forest than in areas characterized as old secondary forest. Extrapolating to the entire protected area, as many as 258 tarsiers may reside in the sanctuary. The vegetation plots where tarsiers were found had substantially more trees per plot, contained trees with larger diameters, and contained slightly taller trees than did the plots where no tarsiers were observed.     

Comparison of ultrasonic vocalizations emitted by rodent pups.

Ultrasonic vocalizations (USVs) emitted by rodent pups, mouse, rat, Syrian hamster, vole, and Mongolian gerbil, were compared as a basic study for a screening test of anti-panic drugs. USVs of rodent pups, separated from their mother under a low temperature condition, were collected by Real-Time Spectrogram (RTS) apparatus, and transformed into spectrograms and power spectra by SIGNAL software. Waveforms of USVs emitted by the rodent pups showed several characteristic features, and species specificity of USVs was shown. We think that the species specificity might be due to differences of the anatomical structures in the respiratory tract and respiratory patterns in rodent pups.     

The skin of primates. XLIII. Further observations on the Philippine tarsier (Tarsius syrichta)

Underneath the volar friction surfaces is a highly developed, anastomosing system of alkaline phosphatase-reactive capillaries; numerous cholinesterase-positive hederiform nerve end-organs are present in the scalp, forehead, lower abdomen, back, and perianal region; sinus hair follicles occur on the flexor surface of the antebrachium; and a dense field of gigantic sebaceous and admixed apocrine glands constitutes the epigastric gland.     

Age affects photoentrainment in a nocturnal primate

The endogenous circadian clock is entrained by external cues, mainly the light-dark cycle received by photopigments located in the retina. The authors investigated (1) the effect of aging on the synchronization of the rest-activity rhythm and (2) the physiological basis of light photoreception in the gray mouse lemur, a nocturnal Malagasy primate. Old individuals were tested at different irradiance levels under 3 different light wavelengths previously shown to trigger maximal response in young adults. Investigators analyzed animal activity and temperature waveforms and used 2 reference treatments, strong white light and continuous darkness. The investigation revealed manifold effects of aging picturing a general loss of responsiveness to light and age-related changes in activity and temperature. In addition, the investigation shows that photoentrainment is a continuous process. Short wavelengths (430 nm) are more efficient than longer wavelengths (470-540 nm) at low light levels at dawn and across all light levels at dusk. This suggests an implication of S-cones, differential at dawn and dusk. This results, surprising for several reasons, calls for further investigation. The study brings an interesting contribution to the understanding of the physiological processes underlying synchronization to light.     

Transmission characteristics of primate vocalizations: implications for acoustic analyses

Acoustic analyses have become a staple method in field studies of animal vocal communication, with nearly all investigations using computer-based approaches to extract specific features from sounds. Various algorithms can be used to extract acoustic variables that may then be related to variables such as individual identity, context or reproductive state. Habitat structure and recording conditions, however, have strong effects on the acoustic structure of sound signals. The purpose of this study was to identify which acoustic parameters reliably describe features of propagated sounds. We conducted broadcast experiments and examined the influence of habitat type, transmission height, and re-recording distance on the validity (deviation from the original sound) and reliability (variation within identical recording conditions) of acoustic features of different primate call types. Validity and reliability varied independently of each other in relation to habitat, transmission height, and re-recording distance, and depended strongly on the call type. The smallest deviations from the original sounds were obtained by a visually-controlled calculation of the fundamental frequency. Start- and end parameters of a sound were most susceptible to degradation in the environment. Because the recording conditions can have appreciable effects on acoustic parameters, it is advisable to validate the extraction method of acoustic variables from recordings over longer distances before using them in acoustic analyses.     

First experimental evidence for female mate choice in a nocturnal primate

Female mate choice can be hypothesised in most nocturnal primates, since females show a higher investment in their offspring than males. The aim of this experimental study was to investigate if female grey mouse lemurs perform mate choice and whether age, relatedness (to the male), or male advertisement call activity systematically influence their decisions. A two-way mate choice design was developed in which females could choose between two males. Mate choice was deduced from the time spent in proximity to the males and from mating behaviour. During oestrus 12 of 17 females participated actively in the experiment and all of them showed either a significant spatial (n=11) or behavioural (n=1) preference for one male. In four cases copulations were observed. The influence of age on female mate choice was not statistically significant. In the cases with copulations, however, females mostly preferred the older male. This might indicate a preference for older age as an indicator of experience, fitness, and/or status. The influence of relatedness on female mate choice could not be definitely clarified. However, results imply a mechanism of kin recognition on the basis of familiarity. In the majority of choices, females preferred the male with higher trill call activity. Since trill call activity correlates with the relative dominance status of males, these results suggest an importance of the male dominance status for female mate choice in grey mouse lemurs. Altogether our findings indicate that females use a complex of different cues to choose their mates.     

Prolactin levels and maternal behavior induced by ultrasonic vocalizations of the rat pup.

The relationship among ultrasonic vocalization (USV), prolactin and maternal behavior was investigated in lactating rat mothers and their pups. The lactating mother had a cannula inserted into the external jugular vein, and was exposed to USVs emitted from a pup immediately. Changes of prolactin and maternal behavior were determined. Prolactin increased dramatically during exposure to USVs, when maternal search, retrieving and nest building behavior appeared significantly. These results suggested that the relationship among USV, prolactin and maternal behavior was included in communication between lactating mother and pup.     

Ontogenetic changes of ultrasonic vocalizations emitted from infant rats.

Ontogenetic changes of USVs were investigated to establish an index of stress in infant rats. The USVs were obtained by exposing infant rats to cold stress and were analyzed by real-time spectrography. USV waveforms consisted of four types, R-I, II, III and IV. These USVs were closely monitored at the age of 3-7 days in both sexes. From day 14, the frequency and incidence of USVs gradually decreased and had disappeared completely at the age of 21 days. Therefore, USVs should be useful in estimating the stress of infant rats between the ages of 3-7 days.     

Structure of rat ultrasonic vocalizations and its relevance to behavior

Rats are known to emit ultrasonic vocalizations (USVs). These USVs have been hypothesized to hold biological meaning, and the relationship between USVs and behavior has been extensively studied. However, most of these studies looked at specific conditions, such as fear-inducing situations and sexual encounters. In the present experiment, the USVs of pairs of rats in ordinary housing conditions were recorded and their features were examined. Three clusters of USVs in the 25-, 40-, and 60-kHz range were detected, which roughly corresponded to fighting, feeding, and moving, respectively. We analyzed sequential combinations of two or more clusters using a state transition model. The results revealed a more specific correspondence between the USVs and behaviors, suggesting that rat USV may work as a type of communication tool.     

Acoustic location of conspecifics in a nocturnal bird: the corncrake Crex crex

Although the use of sounds in spatial orientation is widespread among animals, only a few groups advanced such specific adaptations as echolocation. In contrast, practically all animals and night-active species in particular, must occasionally orient themselves relative to invisible but audible objects such as a hidden rival or predator. In this study, I would like to determine the impact of locating which involves the use of acoustic parameters of sender’s vocalisations by receivers and changes of positions and triangulation of sender’s vocalisations by receivers in estimating the distance to the sender during night-time territorial interactions of the corncrake (Crex crex). Males were subjected to two kinds of stimuli: approaching one, imitating the change of the distance of the calling intruder toward the focal male while keeping the direction constant, or stationary stimuli, involving acoustic stimulation with no motion. Although males subjected to approaching stimulation moved longer distances, in both stimuli groups, males moved predominantly toward or out of the playback speaker, and only occasionally made sideway movements. However, the results gave no evidence of corncrakes moving specifically in order to locate the source of the sound; they suggest that males moved toward or away from the already located sound. The fact that males moved longer distances in response to approaching than stationary stimuli indicates that they were able to perceive the change of the distance to the playback speaker based only on structural parameters or amplitude of the calls played.