Studies on the habitats of Grey Francolin Francolinus pondicerianus (J.F. Gmelin, 1789) (Galliformes: Phasianidae) in northern districts of Tamil Nadu, India

This paper pertains to the habitats of the Grey Francolin Francolinus pondicerianus with specific reference to populations, habitat type, vegetation, foraging, impact of human dwellings, and probable threats to populations in 20 villages covering four northern districts of Tamil Nadu, India. A total of 252 individuals were enumerated. During the non-breeding season, birds move in small groups of 2–6. Of four habitats identified, the maximum number of 143 birds was observed foraging in grasslands, while 61 were seen in dry fallow agricultural lands, 37 in dry lakes/canals, and 11 in harvested fields. No significant association was observed between habitat type and bird behaviour. They feed on termites and spilled paddy grains. Males have repeated loud calls and fight with each other. Four species of tall grasses, six of stunted trees and two shrubs were identified to provide bird habitat. Birds preferred to live away from human dwellings, with 193 found 1,000 m away from settlements. The study area continues to be a suitable habitat for Grey Francolin populations, hence this habitat needs protection.

Get the Vote Out!

Around elections it is common to hear loud calls for citizens of democracies to make themselves heard and vote when important elections take place. This is so prevalent in liberal societies that it oftentimes seems as if the call is to just vote, regardless of how one does so. Is just voting what really matters?

Vocalization Analyses of Nocturnal Arboreal Mammals of the Taita Hills, Kenya

Three poorly known nocturnal mammal species from the montane forests of the Taita Hills in Kenya, were studied via vocalization analysis. Here, their acoustic behaviour is described. The studied animals were the tree hyrax (Dendrohyrax sp.), the small-eared greater galago (Otolemur garnettii), and the dwarf galago (Paragalago sp.). High-quality loud calls were analysed using RAVEN PRO, and compared to calls of presumed closest relatives. Our findings include the first detailed descriptions of tree hyrax songs. Moreover, our results suggest that the tree hyrax of Taita Hills may be a taxon new to science, as it produces a characteristic call, the ‘strangled thwack’, not previously known from other Dendrohyrax populations. Our data confirms that the small-eared greater galago subspecies living in the Taita Hills is Otolemur garnettii lasiotis. The loud calls of the elusive Taita Hills dwarf galago closely resemble those of the Kenya coast dwarf galago (Paragalago cocos). Thus, the population in the Taita Hills probably belongs to this species. The Taita Hills dwarf galagos are geographically isolated from other dwarf galago populations, and live in montane cloud forest, which is an unusual habitat for P. cocos. Intriguingly, two dwarf galago subpopulations living in separate forest patches in the Taita Hills, Ngangao and Mbololo, have clearly different contact calls. The Paragalagos in Mbololo Forest may represent a population of P. cocos with a derived call repertoire, or, alternatively, they may actually be mountain dwarf galagos (P. orinus). Hence, differences in habitat, behaviour, and contact call structure suggest that there may be two different Paragalago species in the montane forests of the Taita Hills.

Baffling: A cheater strategy using self-made tools in tree crickets

Intense sexual selection in the form of mate choice can facilitate the evolution of different alternative reproductive strategies. These strategies can be condition-dependent, wherein genetically similar individuals express the strategy based on their condition. Our study shows that baffling, a mate attraction strategy using self-made acoustic amplifiers, employed by male tree crickets, is a classic example of a condition-dependent alternative strategy. We show that less preferred males, who are smaller or produce less loud calls, predominantly use this alternative strategy. Baffling allows these males to increase their call loudness and advertisement range, and attract a higher number of mates. Baffling also allows these males to deceive females into mating for longer durations with them. Our results suggest that the advantage of baffling in terms of sperm transfer is primarily limited to less preferred males, thus maintaining the polymorphism of calling strategies in the population.Impact statementThis study shows that less preferred tree cricket males use an alternative signaling strategy to call louder, thus attracting and mating with otherwise choosy females using deception.

Modeling active sensing reveals echo detection even in large groups of bats

Active sensing animals perceive their surroundings by emitting probes of energy and analyzing how the environment modulates these probes. However, the probes of conspecifics can jam active sensing, which should cause problems for groups of active sensing animals. This problem was termed the cocktail party nightmare for echolocating bats: as bats listen for the faint returning echoes of their loud calls, these echoes will be masked by the loud calls of other close-by bats. Despite this problem, many bats echolocate in groups and roost socially. Here, we present a biologically parametrized framework to quantify echo detection in groups. Incorporating properties of echolocation, psychoacoustics, acoustics, and group flight, we quantify how well bats flying in groups can detect each other despite jamming. A focal bat in the center of a group can detect neighbors in group sizes of up to 100 bats. With increasing group size, fewer and only the closest and frontal neighbors are detected. Neighbor detection is improved by longer call intervals, shorter call durations, denser groups, and more variable flight and sonar beam directions. Our results provide a quantification of the sensory input of echolocating bats in collective group flight, such as mating swarms or emergences. Our results further generate predictions on the sensory strategies bats may use to reduce jamming in the cocktail party nightmare. Lastly, we suggest that the spatially limited sensory field of echolocators leads to limited interactions within a group, so that collective behavior is achieved by following only nearest neighbors.

Active sensing in groups: (what) do bats hear in the sonar cocktail party nightmare?

ABSTRACTActive sensing animals perceive their surroundings by emitting probes of energy and analyzing how the environment modulates these probes. However, the probes of conspecifics can jam active sensing, which should cause problems for groups of active sensing animals. This problem was termed the cocktail party nightmare for echolocating bats: as bats listen for the faint returning echoes of their loud calls, these echoes will be masked by the loud calls of other close-by bats. Despite this problem, many bats echolocate in groups and roost socially. Here, we present a biologically parametrized framework to quantify echo detection in groups. Incorporating known properties of echolocation, psychoacoustics, spatial acoustics and group flight, we quantify how well bats flying in groups can detect each other despite jamming. A focal bat in the center of a group can detect neighbors for group sizes of up to 100 bats. With increasing group size, fewer and only the closest and frontal neighbors are detected. Neighbor detection is improved for longer call intervals, shorter call durations, denser groups and more variable flight and sonar beam directions. Our results provide the first quantification of the sensory input of echolocating bats in collective group flight, such as mating swarms or emergences. Our results further generate predictions on the sensory strategies bats may use to reduce jamming in the cocktail party nightmare. Lastly, we suggest that the spatially limited sensory field of echolocators leads to limited interactions within a group, so that collective behavior is achieved by following only nearest neighbors.SIGNIFICANCE STATEMENTClose-by active sensing animals may interfere with each other. We investigated if and what many echolocators fly in a group hear – can they detect each other after all? We modelled acoustic and physical properties in group echolocation to quantify neighbor detection probability as group size increases. Echolocating bats can detect at least one of their closest neighbors per call up to group sizes of even 100 bats. Call parameters such as call rate and call duration play a strong role in how much echolocators in a group interfere with each other. Even when many bats fly together, they are indeed able to detect at least their nearest frontal neighbors – and this prevents them from colliding into one another.