Dinesh Bhatt

Effect of pinealectomy on free-running reproductive cycle of tropical spotted munia

SummaryThe breeding cycle of the tropical spotted munia (Lonchura punctulata) is regulated by the photoperiodic synchronization of an endogenous circannual rhythm. Since the pineal gland has been implicated in circadian periodicity, in an attempt to understand the functioning of the mechanism(s) involved in photoperiodic synchronization of the circannual clock in the spotted munia the effect of pinealectomy on the reproductive cycle was studied in birds maintained in normal entrained (natural day length, NDL) and free-running (constant light, LL) conditions.Results indicate that pinealectomy had no effect in LL but that the reproductive cycle was altered marginally (in the first cycle only), and the body weight cycle drastically, in NDL conditions. It seems that the marginal effects observed on the overt reproductive cycle in the entrained condition may not be through the circannual oscillator itself but may perhaps reflect interference with processes involved in photoperiodic synchronization of the circannual rhythm. Alternatively, these effects could also result from general metabolic disturbances caused in the body by the absence of the pineal gland.

How relevant are the concepts of species diversity and species richness

Biodiversity is a science that is still in its infancy or, in the words of Ernst Mayr (1997), at the ‘what’ stage. The inventorying and monitoring of biological diversity have just started for a few taxonomic groups and have yet to be initiated for most taxa. As biodiversity equals variety at the species level of biological organization, the terms species richness and species diversity have become key concepts in conservation biology. Both concepts are important characteristics of community structure. Therefore, much has been published on the measurement of the species richness and species diversity of communities (MacArthur 1955; Hurlbert 1971; Peet 1974; Pielou 1975; Magurran 1988, 2004; Schluter and Ricklefs 1993; Colwell and Coddington 1994; Krebs 1999). However, a certain looseness in the use of these terms is still found in the literature, for example when they are used interchangeably (see Cotgreave and Harvey 1994; Harrison et al 2000). This has led to a some confusion. In this Commentary, the concepts of species richness and species diversity are discussed in the light of recent developments. It is suggested that a clear distinction needs to be made between the two if we are to avoid further confusion surrounding these terms. We also introduce a simple diagram through which species number, species abundance, and species diversity can be represented in an integrated manner.

Vocal signals in a tropical avian species, the redvented bulbulPycnonotus cafer: their characteristics and importance

Acoustic signals play an important role in the lives of birds. Almost all avian species produce vocal signals in a variety of contexts either in the form of calls or songs or both. In the present study different types of vocal signals of the tropical avian speciesPycnonotus cafer were characterized on the basis of their physical characteristics and context of production. This species used six types of vocal signals: contact signals, roosting signals, alarm signals, twittering signals, distress signals and begging signals. Two types of alarm signals are produced based on predation pressure. These signals are dissimilar in all physical characteristics except for dominant frequency. Although alarm signal type I and roosting signals are phonetically similar, they have completely different sonogram characteristics.

Nesting success of the oriental magpie robin Copsychus saularis in nest boxes and tree cavities

Information on the nesting success of birds in the Indian subcontinent is almost negligible. In the present study factors affecting nesting success were studied over four years (i.e. 2011–2014) in a color ringed population of the oriental magpie robin (OMR) in an urban habitat of Haridwar district (29°55′N, 78°08′E), Uttarakhand, India. Objectives of our study were 1) to assess whether nest box affects nesting success in the OMR or not 2) to compare breeding data obtained from nest boxes with tree cavities. Out of total 114 nests built in both nest boxes and tree cavities, 80 nests were successful in producing at least one fledgling resulting 69.25% nesting success. Nesting success did not differ significantly between nest boxes and tree cavities or during different years. No correlation was found between territory size and nesting success (correlation coefficient = 0.41). Observations indicated that predation accounted for the maximum egg loss and nestling mortality. Predation rate was higher in tree cavities but did not differ significantly during different years and between nest boxes and tree cavities. In all years but 2011 clutch size was significantly higher in nest boxes than in tree cavities. However, incubation period, provisioning period, number of eggs hatched and number of young fledged did not differ significantly between nest boxes and tree cavities. When provided, nest boxes were occupied more frequently at all study sites indicating that nest box may act as an alternative nesting site for the OMR and perhaps for other secondary cavity nesters facing scarcity of nesting sites due to rapid urbanization.

PROVISIONING OF YOUNG BY THE ORIENTAL MAGPIE-ROBIN (COPSYCHUS SAULARIS)

Abstract Information on provisioning behavior of birds in the Indian subcontinent is almost negligible. We studied provisioning of nestlings of the Oriental Magpie-robin (Copsychus saularis) in 11 nests in relation to brood size, nestling age, and time of day during March–July 2006. Both parents fed the nestlings. However, the rate of provisioning trips by females was higher (t = 9.51, df = 10, P < 0.01) than for males. Brood size and time of day did not affect the provisioning rate. Age of nestlings was an important factor affecting rate of parental provisioning. Nestlings were fed more as they became older and there was correlation (Spearmans rho = 1) between parental provisioning trips and nestling age.

Avian species distribution in different elevation zone forest (Sal, Pine Mixed And Oak) in nainital district of uttarakhand, India

The present study were made to estimate the avian fauna in terms of species richness and diversity and guild structure in forest habitats of Nainital district of Uttarakhand (350–2.450 m asl; 29° N). Field studies were conducted during January 2007 to December 2008. Total 43, 62 and 42 species were recorded from, Haldwani, Bhowali and Nainital forest habitats. Results indicate the species relationship between Bird species richness (BSR) and elevation sections (forest habitats) was not decline simultaneously along elevation; it shows hump shaped. BSR varied considerably along elevational gradient (43 to 62 species), was highest (62 species) at mid elevation (Mixed pine forest, 1.350–1.700 m asl) and decreased (20 species) at high elevation (Conifer forest, 1900–2450 m asl). It seems that mid altitude bulge is not caused by the presence of a group of mid altitude specialists but rather that there is an overlap in the distribution of low land and high elevation specialists at this altitude. A checklist of 79 avian species has also produced of Nainital district forest habitats. It is suggested that this study provide a base line structure for further study on species distribution in different forest habitats and along different elevation section in Western Himalayas (India).

Mitochondrial and Nuclear DNA Based Genetic Assessment Indicated Distinct Variation and Low Genetic Exchange Among the Three Subspecies of Swamp Deer ( Rucervus duvaucelii )

The swamp deer (Rucervus duvaucelii) occurs, primarily, in the wet grasslands of the Himalayan foothills as well as the dry grasslands of central India. Three subspecies have been identified, namely R. duvaucelii duvaucelii, R. duvaucelii branderi and R. duvaucelii ranjitsinhi. Degradation of grassland habitats led to a drastic decline in the total swamp deer population in the early 19th century. Even though the species has recently shown signs of recovery, it is still vulnerable to the small-population paradigm. Effective management plans need to be put in place to increase the population through scientific intervention. The current genetic variation within the three subspecies of R. duvaucelii is unclear, and this is hindering effective conservation planning. We examined the genetic variability, population structure and demography of the three subspecies of swamp deer using the mtDNA control region and microsatellite analysis. Despite the spatial isolation of the populations, we found a high level of variation and weak divergence among the subspecies. The genetic differentiation (FST) between the subspecies and the mismatch distribution of haplotypes indicated recent colonization by these subspecies. Population bottleneck analysis indicated that the existing subspecies and their populations are at demographic equilibrium and are stable. The study highlights the need for effective conservation management intervention to maintain the population size and genetic diversity. It also indicates that all the subspecies need to be managed as separate conservation units.

Relationship Between Song Repertoire Size With Nesting Success, Territory Size, and Territorial Conflict In Pied Bush Chat (Saxicola capratA)

ABSTRACT.— We studied the relationship between song repertoire size, territorial behavior, and nesting success in Pied Bush Chat (Saxicola caprata) in Haridwar (Himalayan foothills), India for three consecutive years (2013–2015). Our findings indicate song repertoire size is correlated with nesting success, but pre-nesting territory size, average territory size, and territorial conflicts are independent of song repertoire size. It may be inferred that larger territories are not necessarily better territories. The findings suggest that larger territory size is more susceptible to increased territorial conflict. Significant differences were apparent between territory size and territorial conflicts in the different stages of the nesting cycle. The findings suggest that larger territory size is more susceptible to increased territorial conflict. We propose that even if territorial conflicts are independent of song repertoire size, the amount of territorial conflict may be constrained by the stage of nesting cycle or size of the territory. Depending upon breeding requirements, male Pied Bush Chats tailor their territory sizes and territorial conflicts during the course of the breeding season.

Singing Patterns of Male Pied Bush Chats (Saxicola caprata) Across Years and Nesting Cycles

ABSTRACT.— We investigated singing patterns of Pied Bush Chats across years and nesting cycles. We recorded the seasonal singing activity of 25 males in their natural habitats in Haridwar, Himalayan foothills, India for three consecutive years. The vocal patterns, especially song repertoire size of males, remained largely constant, and this restricted annual variation suggests that the Pied Bush Chats are closed-end learners. Analysis of song bouts during different stages of the nesting cycle and across years indicates that the Pied Bush Chat is an immediate variety singer. The song output in terms of song complexity, song rate, song bout length, and percentage performance time was highest at the beginning of egg laying and during incubation compared to pre-nesting, nest building, and provisioning stages. Such singing peaks with respect to different stages of the nesting cycle indicated mate guarding by male Pied Bush Chats and announcement of fertility status of the guarded female.

Response of Male Pied Bushchats Saxicola caprata to Playback of the Songs of Neighbours and Strangers

Abstract Discrimination between neighbours and strangers, on the basis of acoustic cues, has been clearly demonstrated in many temperate avian species, but experiments on neighbour-stranger recognition have received less attention in tropical habitats, particularly in the Indian subcontinent. With this in mind, neighbour—stranger discrimination experiments were conducted on tropical male Pied Bushchats Saxicola caprata in the District Haridwar, of the Himalayan foothills, India. The sound levels of broadcasted songs were kept as close as possible to natural song levels. The results of the parameters analysed (including song rate, song repertoire, flights toward the speaker, distance from the speaker, and latency) did not differ significantly between neighbour and stranger song playbacks. It seems that male Pied Bushchats responded evenly toward the playback and may be incapable of discriminating between neighbours and strangers.