Environmental and hormonal control of vernal migration in redheaded bunting (Emberiza bruniceps)

This paper reviews the factors and mechanisms which result in the development of the metabolic state characteristic of migration with special reference to a palaeotropic migrant the redheaded bunting, Emberiza bruniceps. Changes in climatic conditions and food supply act as proximate triggers of migratory behaviour in partial migrants. Typical migrants like buntings use daylength as a cue but the exact mechanism of how photoperiodic information is translated in terms of migratory events is still not known. Almost entirely the photoperiodic effects have been explained on the basis of the involvement of hypothalamo/hypophyseal system. We feel mechanism(s) other than those acting through neuroendocrine system may be equally important. Furthermore the role of temperature has not been adequately explored so far. Our observations indicate the possibility that redheaded buntings might integrate the information received from photoperiod with environmental temperature (and other factors?) resulting in the development of migratory state. The physiological control of avian migration is much less understood. Majority of papers have centered around the 'gonadal hypothesis' of Rowan supporting or contradicting it without providing conclusive evidence. Pituitary prolactin has also been shown to be implicated although the mechanism of action is only speculative. Conclusive evidence for the involvement of thyroid hormones (thyroxine, T4; triiodothyronine, T3) in the physiological timing of migration has been produced attributing independent roles to T4 and T3. It is suggested that seasonal variation in peripheral conversion of T4 to T3 could serve as an effective strategy to render available the required thyroid hormones T4 and/or T3 during different phases of the year thus accounting for the metabolic switch over from T4-dependent moult to T3-dependent migratory fat deposition and zugunruhe and also ensuring preclusion of simultaneous occurrence of these mutually incompatible events. Considering that the number of environmental and physiological factors influence this mechanism and considering that thyroid hormone molecule has been put to a wide range of usage during the course of evolution the mechanism(s) of peripheral conversion of T4-T3 may assume great flexibility and have selective value-especially in migration which is known to have evolved several times in diverse avian families. The attractiveness of this hypothesis lies in the fact that it has potential to explain the both physiological development of the metabolic state of migration and at the same time the physiological timing of migration not only with respect to the cycle of environment but also with respect to other conflicting seasonal events (moult and reproduction)

Chronobiotic effect of melatonin following phase shift of light/dark cycles in the field mouse Mus booduga

The objective of this study was to assess whether melatonin accelerates the re-entrainment of locomotor activity after 6 h of advance and delay phase shifts following exposure to LD 12:12 cycle (simulating jet-lag/shift work). An experimental group of adult male field mice Mus booduga were subjected to melatonin (1 mg/kg) through i.p. and the control group were treated with 50 % DMSO. The injections were administered on three consecutive days following 6h of phase advance and delay, at the expected time of "lights off". The results show that melatonin accelerates the re-entrainment after phase advance (29%) when compared with control mice. In the 6 h phase delay study, the experimental mice (melatonin administered) take more cycles for re-entrainment (51%) than the control. Further, the results suggest that though melatonin may be useful for the treatment of jet-lag caused by eastward flight (phase advance) it may not be useful for westward flight (phase delay) jet-lag

Genetic diversity within and among populations of the Indian short-nosed fruit bat, Cynopterus sphinx assessed through RAPD analysis

Genetic diversity was studied among 40 different zone samples in the Indian short-nosed fruit bat, Cynopterus sphinx. Samples were collected from 127 locations in different districts of southern Tamil Nadu, India. Polymorphism at molecular level was studied by random amplified polymorphic DNA marker technique. Polymerase chain reaction (PCR) with 30 arbitrary decamer oligonucleotide primers was applied to the 40 zone samples. Out of 30 random primers screened, 22 gave reproducible polymorphic bands. PCR product of bat genome revealed a total of 234 bands, out of which 171 were found to be polymorphic. The dendrogram displaying the relative genetic similarities between the zones ranged from 0.42 to 0.92. Principal coordinates analysis revealed that the first two components accounted for 51.4% of the total variation. The results show that considerable genetic diversity was observed in this species from different zonal populations, possibly due to complete dispersal of juveniles of both sexes from their natal groups and gene flow between the zones. The results obtained from this study suggest not only a predictive framework for future studies, but also the use of genetic data in the management and meaningful conservation of this species

Early ontogeny of foraging behaviour in the short-nosed fruit bat Cynopterus sphinx (Megachiroptera) : preliminary results

This article does not have an abstract

Plant ecology meets animal cognition: impacts of animal memory on seed dispersal

We propose that an understanding of animal learning and memory is critical to predicting the impacts of animals on plant populations through processes such as seed dispersal, pollination and herbivory. Focussing on endozoochory, we review the evidence that animal memory plays a role in seed dispersal, and present a model which allows us to explore the fundamental consequences of memory for this process. We demonstrate that decision-making by animals based on their previous experiences has the potential to determine which plants are visited, which fruits are selected to be eaten from the plant and where seeds are subsequently deposited, as well as being an important determinant of animal survival. Collectively, these results suggest that the impact of animal learning and memory on seed dispersal is likely to be extremely important, although to date our understanding of these processes suffers from a conspicuous lack of empirical support. This is partly because of the difficulty of conducting appropriate experiments but is also the result of limited interaction between plant ecologists and those who work on animal cognition

<span style="font-size: 20.0pt;mso-bidi-font-size:14.0pt;font-family:"Times New Roman","serif"; color:black">Roosting patterns in a captive colony of short-nosed fruit bat <i>Cynopterus sphinx </i>(Vahl) </span>

1187-1190<span style="font-size: 14.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif";="" color:black"="">Development of roosting patterns under a limited resource was studied in the short-nosed fruit bat <span style="font-size:15.0pt; mso-bidi-font-size:9.0pt;font-family:" times="" new="" roman","serif";color:black"="">C. sphinx <span style="font-size:14.5pt;mso-bidi-font-size: 8.5pt;font-family:" times="" new="" roman","serif";color:black"="">in captivity. Spatial fidelity during the resting period (day time) and the individual male bat's presence/absence in the roost <span style="font-size: 14.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif";="" color:black"="">(occupancy index) were estimated during the active period (night time). Results show the presence of three groups on the basis of spatial fidelity. The first group was associated with the tent consisting of a harem male and seven females. The <span style="font-size: 14.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif";="" color:black"="">second group stayed near to the harem. The third group consisting of two males showed little occupancy index and no spatial fidelity. Female turnover between the first and second groups, and harem male replacement were observed. These findings of male groupings and female loyalty on the basis of "resource", suggest that resource defence pulygyny is the primary mating strategy in <span style="font-size:15.0pt;mso-bidi-font-size: 9.0pt;font-family:" times="" new="" roman","serif";color:black"="">C. sphinx. </span

Presence of single as well as double clicks in the echolocation signals of a fruit bat, Rousettus leschenaulti (Chiroptera : Pteropodidae)

We studied the structure of calls emitted by the echolocating fruit bat Rousettus leschenaulti (Megachiroptera: Pteropodidae) while flying inside a free-flight room. The echolocation sounds consists of both single as well as double clicks, with single clicks emitted either in the beginning or at the end of click sequences. The duration of clicks was brief, about 1.6 ms and most of the acoustic energy is between 18 to 32 kHz. The use of simple, brief impulsive clicks and the reduction of interpulse interval and duration, when approaching the sides of the walls suggest that they have a good capability of obstacle avoidance as similar to microchiropteran bats. Furthermore, the production of both single as well as double clicks like cave swiftlets in orientation flights has an implication for the evolution of echolocation in bats

Seasonal Food Preference of the Indian Short Nosed Fruit Bat Cynopterus Sphinx(Vahl) (Chiroptera: Pteropodidae)

Volume: 96Start Page: 24End Page: 2

Performance characteristics of organic–inorganic composite electrodes in magnesium reserve batteries

Electrochemical characteristics of m-dinitrobenzene (m-DNB) based composite cathode materials involving compounds such as AgCl, TiO2, HgO and CuCl have been investigated and (Mg AZ31 alloy anode) as an activated battery system using 2 M magnesium perchlorate aqueous electrolyte. The concentration of the composites has been optimized so as to obtain high electrochemical performance of Mg/m-DNB reserve batteries through constant current discharge studies. Mg/m-DNB cells containing 5-wt % of HgO when discharged at current density of 2.1 mA cm)2 delivered 5.3 Ah capacity corresponds to a columbic efficiency of 97% as compared to the cells without composite