Perch Hunting Research Articles

HABITAT DAN PERILAKU ELANG JAWA (Nisaetus bartelsi ) DI SPTN 1 TEGALDLIMO TAMAN NASIONAL ALAS PURWO, JAWA TIMUR

Javan Hawk-eagle (Nisaetus bartelsi) considered as endangered species by IUCN redlist 2015 and protected species by Government Regulation No . 7/1999. Alas Purwo National Park (APNP) is a conservation area and its one of the natural habitat of Javan Hawk-eagle distribution (endemic species of java). The study was aimed to analysis its habitat and the behavior. Purposive sampling was used on focused observation area base on direct contex with the bird. The habitat analysis was approach with vagetation analysis dan habitat used method. Focal animal sampling used as approach describe to know the daily activities. The result showed that the bird used of natural lowland forest as main habitat and the bird distibute as equal (focused) at natural lowland forest. Characteristic of sheltering site of the bird using tree in A strata and B strata, which have horizontal and strong enough branch. The javan hawk-eagle choising at emergent tree for the nesting site, with characteristic of emergent tree, with crown not so dense of the leaf and the position of the tree close to hunting area. Characteristic of hunting areas of the bird is natural lowland forest with diverse and abundant of preys. The bird like preys on mammals such as giant squirrel and bird such as red jungle fowl. The behavior was most often observed was resting in natural lowland forest with five times encounter (58,06%). But the bird also done activities of preening and observing surrounding to focus on seaching food. Hunting activity was observed used perch hunting in natural low land forest in APNP. Keywords: APNP, habitat, javan hawk-eagle

Echolocation intensity and directionality of perching and flying fringe-lipped bats, Trachops cirrhosus (Phyllostomidae)

The Neotropical frog-eating bat, Trachops cirrhosus, primarily hunts stationary prey, either by gleaning on the wing, or in a sit-and-wait mode hanging from a perch. It listens passively for prey-generated sounds, but uses echolocation in all stages of the hunt. Like other bats in the family Phyllostomidae, T. cirrhosus has a conspicuous nose leaf, hypothesized to direct and focus echolocation calls emitted from the nostrils. T. cirrhosus is highly flexible in its cognitive abilities and its use of sensory strategies for prey detection. Additionally, T. cirrhosus has been observed to echolocate both with closed and open mouth. We hypothesize that its flexibility extends to echolocation call design. We investigated the effect of hunting mode, perching or flying, as well as the effect of mouth opening, on the acoustic parameters and directionality of the echolocation call. We used a multi-microphone array, a high-speed video camera, and a microphone-diode-video system to directly visualize the echolocation sound beam synchronized with the bat's behavior. We found that T. cirrhosus emits a highly directional sound beam with half amplitude angle (HAM) of 12–18° and DI (directionality index) of ~17 dB, among the most directional bat sonar beams measured to date. The directionality was high both when flying and when perching. The emitted intensity was low, around 88 dB SPL at 10 cm from the mouth, when hanging, but higher, around 100 dB SPL at 10 cm, when flying or just before take-off. Our data suggests that the limited search volume of T. cirrhosus sonar beam defined by the high directionality and the rather low intensity of its echolocation calls is adapted to the highly cluttered hunting habitat and to the perch hunting mode.

Eigensurface analysis, ecology, and modelling of morphological adaptation in the falconiform humerus (Falconiformes: Aves)

Studies of morphological adaptation aim to quantify the relationship between an organism's form and its ecology. In the past such studies have been hampered by an over-reliance on either qualitative observations or the collection of a few, marginally representative two-dimensional linear measurements as morphological descriptors. Recent advances in morphometric data acquisition and analysis techniques now provide a means of accurately and comprehensively quantifying the morphological variation inherent in complex three-dimensional (3D) surfaces across a specimen set. Using birds of prey as a model group, we examine how one of these new morphometric methods – eigensurface analysis – can be used to investigate adaptation. Virtual models of the humerus of 50 falconiform species from 29 genera were examined to identify the morphological correlates associated with different flight styles, habitats, and behaviours of these ecologically sensitive predators. Results indicate that strong, consistent, unique, and subtle modes of shape variation are associated with differences in flight speed (fast–slow), flight style (perch hunting, chasing, low flight, soaring flight, hovering), habitat (forested–open landscape) and migratory behaviour (long-distance migrants–sedentary species). In each case, visual modelling of between-groups transitions in morphology can be used to facilitate identification of features of the humerus, such as the size and extent of surface-shape variation within specific regions of muscle attachment, that are important predictors of function and lifestyle. Eigensurface analysis-based representations of 3D morphology, in combination with standard linear discrimination techniques and new shape modelling procedures, represent a way to statistically evaluate hypotheses of morphological adaptation. This approach can be used not only for bird taxa, but more broadly in studies of ecology and adaptation in many vertebrate, invertebrate, and plant species, in ways that cannot be duplicated either by visual observation or by the representation of form using linear measurements, 2D–3D landmark coordinate sets or sets of 2D–3D boundary outline semilandmarks. © 2012 The Trustees of the Natural History Museum. Zoological Journal of the Linnean Society© 2012 The Linnean Society of London, 165, 390–419.

Foraging area and hunting technique selection of Common Kestrel ( Falco tinnunculus) in winter: the role of perch sites

In winter, Common Kestrel minimizes energy expenditure by using the low-cost, low-profit technique of perch hunting. Existence of the perch sites is the precondition of perch hunting. Therefore, one can predict that the kestrels would prefer a habitat with more perch sites, and perch sites should have an important role in the kestrels' hunting technique use, habitat selection and habitat use in winter. To test this prediction, the authors manipulated two areas in a grassland. They increased the potential perch sites in one area with bamboo poles (hereafter test area) and kept another as control (hereafter control area). They observed and compared the kestrels' use and their behaviors in these two areas. Far more kestrels appearing in the test area with increasing perch sites than in the control area were recorded. The kestrels stayed in the test area with more perch sites significantly longer than in the control area. And in the test area with more perch sites, kestrels hunted 77.24% of the total hunting with the technique of perch hunting. In the control area, kestrels hunted only with the technique of flight-hunting. There was a significant correlation between the technique used by kestrels and the areas with or without perch sites. In the test area with increasing perch sites kestrels spent 51.8% of their time in perching and 12.1% in air, which were 30.1% and 34.8%, respectively, in the control area. There was no significant difference in hunting profit between areas. The results suggest that perch sites play an important role in the selection of hunting technique and foraging habitat for kestrels in winter, and kestrels appear to prefer the habitat with suitable perch sites in winter.

MORPHOLOGICAL CHARACTERISTICS PREDICT ALTERNATE FORAGING STRATEGY AND MICROHABITAT SELECTION IN THE ORANGE-BELLIED BAT, LAMPRONYCTERIS BRACHYOTIS

Neotropical bat species may coexist because they forage in different places or in different ways. The small insectivorous orange-bellied bat, Lampronycteris brachyotis (Phyllostomidae), differs from coexisting gleaners in key ecomorphological characteristics, including longer, narrower wings and smaller ears. Using telemetry, we measured range size, range use, and activity patterns, and assessed habitat preferences for 9 individuals for 50 nights over 4 months on Barro Colorado Island, Panama. The bats spent the night in individual, medium-sized (22–27 ha) foraging areas within forested regions close to shorelines, up to 4 km away from the day roost. Each bat spent most of its time in a small (3–5 ha) core area. Foraging flights ranged from a few s to more than 70 min. Total flight time per night averaged 3.5 h and flight distance was estimated to be 60 km. There were no distinct activity peaks. Our tracking data suggest that L. brachyotis primarily forages in the canopy, where it gleans insects from vegetation in a combination of perch hunting and continuous flight. This species may also catch insects in air above the canopy. This unique behavior among gleaning insectivorous phyllostomids corroborates our hypothesis that morphological adaptations combined with behavioral flexibility reflect distinct differences in foraging strategies and microhabitat selection. We conclude that differential use of space and hunting strategies promotes coexistence among the species-rich guild of Neotropical insectivorous gleaning bats.

Foraging ecology of the horseshoe bat, Rhinolophus megaphyllus (Rhinolophidae), in eastern Australia

The foraging ecology of the eastern horseshoe bat, Rhinolophus megaphyllus, was examined at five sites spread along 2100 km of its Australian distribution in coastal Queensland. Foraging strategy and prey-capture behaviour of light-tagged bats were similar across sites. Bats were observed foraging during continuous flight at all sites, whereas perch hunting was observed (rarely) at only one site. Bats captured insects by aerial hawking, with a single record of gleaning. In rainforest bats spent most time close to vegetation whereas openings were favoured in open forest/woodland. Only flying insects were captured and, although a wide range of taxa was taken, Lepidoptera (all sites) and Coleoptera (all sites except one) were the primary prey. Occurrence in faeces of Lepidoptera, Coleoptera, and other taxa combined, varied across sites and across seasons, but there was no three-way interaction between taxon, site and season. Comparison of insect taxa in faeces with those captured in a light-trap set at foraging grounds indicated that insects were selectively captured by R. megaphyllus. The foraging ecology of R. megaphyllus is similar to that of other horseshoe bats in its relative stability across a large geographic range. Although the species is currently not of conservation concern in Australia, aspects of its foraging ecology suggest that it may become regionally threatened in areas with high levels of vegetation clearance.

The relationships between echolocation calls, morphology and diet in insectivorous bats

AbstractIn this study we explored quantitatively the relationships between the size of bats, the frequencies in their echolocation calls, and the incidence of moths and beetles in their diets. We focused on the predictions of the allotonic frequency hypothesis which states that some insectivorous bats increase their access to moths that can hear echolocation calls by shifting to frequencies to which the ears of these insects are less sensitive. The hypothesis predicts that the frequencies dominating the echolocation calls of bats may be correlated with the incidence of moths in their diets. We collected data for 62 species of bats that take airborne prey, usually flying insects, 25 species of high duty cycle echolocating bats (Rhinolophidae and Hipposideridae) and 37 species that are low duty cycle echolocators (Vespertilionidae and Molossidae). For bats whose echolocation calls are dominated by frequencies < 100 kHz our regression analyses showed a parabolic dependency between moth consumption (% volume or % frequency) and echolocation call frequency (kHz), supporting the allotonic frequency hypothesis. The use of echolocation calls dominated by frequencies outside the range of best hearing by moths may indeed increase the availability of these insects to the bats. However, when the same analysis was performed with only the bat species using echolocation calls dominated by sounds > 100 kHz, the relationship was not statistically significant, suggesting that morphological characteristics rather than echolocation call frequency may limit the range of potential prey items. Our analyses also demonstrate the importance of jaw morphology as a predictor of the incidence of beetles or moths in the diets of bats, and reveal that generally bigger species (as defined by forearm length) use echolocation calls dominated by lower frequencies than smaller species. In both high duty and low duty cycle echolocating bats the relationship between body size and dominant call frequency was best described by a linear model. We also propose that perch hunting was central in the development of the high duty cycle approach to echolocation.

The relationships between echolocation calls, morphology and diet in insectivorous bats

In this study we explored quantitatively the relationships between the size of bats, the frequencies in their echolocation calls, and the incidence of moths and beetles in their diets. We focused on the predictions of the allotonic frequency hypothesis which states that some insectivorous bats increase their access to moths that can hear echolocation calls by shifting to frequencies to which the ears of these insects are less sensitive. The hypothesis predicts that the frequencies dominating the echolocation calls of bats may be correlated with the incidence of moths in their diets. We collected data for 62 species of bats that take airborne prey, usually flying insects, 25 species of high duty cycle echolocating bats (Rhinolophidae and Hipposideridae) and 37 species that are low duty cycle echolocators (Vespertilionidae and Molossidae). For bats whose echolocation calls are dominated by frequencies < 100 kHz our regression analyses showed a parabolic dependency between moth consumption (% volume or % frequency) and echolocation call frequency (kHz), supporting the allotonic frequency hypothesis. The use of echolocation calls dominated by frequencies outside the range of best hearing by moths may indeed increase the availability of these insects to the bats. However, when the same analysis was performed with only the bat species using echolocation calls dominated by sounds > 100 kHz, the relationship was not statistically significant, suggesting that morphological characteristics rather than echolocation call frequency may limit the range of potential prey items. Our analyses also demonstrate the importance of jaw morphology as a predictor of the incidence of beetles or moths in the diets of bats, and reveal that generally bigger species (as defined by forearm length) use echolocation calls dominated by lower frequencies than smaller species. In both high duty and low duty cycle echolocating bats the relationship between body size and dominant call frequency was best described by a linear model. We also propose that perch hunting was central in the development of the high duty cycle approach to echolocation.

Colony sizes, roost use and foraging ecology of Hipposideros diadema reginae, a rare bat from tropical Australia

Hipposideros diadema reginae is a rare subspecies of Diadem Leafnosed Bat confined to tropical Queensland. Few data are available on its population size or ecology. From July, 1990 to December, 1993, I conducted colony counts at Chillagoe and Iron Range to assess its abundance, and radio-tagged six males at Chillagoe to provide data on roosting and foraging ecology for management purposes. I recorded the subspecies in nine of 18 caves surveyed at Chillagoe. Two or more bats were regularly observed in only four caves, each of which had =250 m of passage, large chambers with high domed ceilings, and multiple entrances. The largest colony was found in Trezkinn Cave (range of 6?65 bats). Both Trezkinn and a nearby cave, Donna, were fully developed tourist caves, but were frequently used as day roosts by radio-tagged bats. Each cave had a gate at its entrance. At Iron Range, between 70 and 250 bats roosted in Gordon's Mine. Bats used multiple day roosts, but did not change roost every day. The main foraging behaviour was perch hunting, with continuous flight as a secondary behaviour. The mean foraging range of tagged bats was 1.08 km from the day roost (range of 0.3?2.5 km). Foraging occurred within all available types of vegetation; use of vegetation showed intraspecific variation. Hipposideros d. reginae exhibits flexibility in its foraging ecology, but has specific roost requirements. Recommended management actions are: prevent or regulate human access to roosts, search for additional colonies at Chillagoe by targeting potentially suitable caves, and ban scientific collecting at both sites.

The diets of British bats (Chiroptera)

Sixty‐one studies of the diets of 15 species of bats found in the British Isles are reviewed. Fourteen studies describe the diets of more than one species. Barbastella barbastellus and Plecotus spp. eat mainly Lepidoptera. Eptesicus serotinus takes mainly Coleoptera, but feeds on a wide range of prey, found in several habitats. Rhinolophus ferrumequinum hunts mainly Coleoptera and Lepidoptera by hawking, gleaning and perch hunting. Myotis bechsteinii takes mostly woodland families of Diptera and Lepidoptera. The remaining nine species eat mainly Diptera. Myotis nattereri feeds almost entirely on diurnal Diptera, gleaned from their nightly resting places. Rhinolophus hipposideros and Myotis mystacinus take mostly swarming crepuscular Diptera by hawking, probably near water and in damp wooded areas; both also glean. Myotis brandtii feeds on Diptera by hawking and gleaning; Nyctalus noctula by hawking. Myotis daubentonii, Pipistrellus spp. and Nyctalus leisleri eat many aquatic Diptera, and may therefore be expected to feed close to freshwater habitats. M. daubentonii hunts by trawling aquatic Diptera from the surface of water.

Morphometrics and Flight Performance of Southern African Peregrine and Lanner Falcons

Twenty-four morphometric parameters were measured from samples of live southern African Peregrine Falcons Falco peregrinus minor and Lanner Falcons F. biarmicus biarmicus. The two species were different in most measurements, especially those relevant to prey capture and handling techniques, and flight performance (bill size, foot size, wing span, wing area, tail length and wing loading). Flight performance parameters calculated from mensural data predicted significant differences in the flying abilities of the two species, notably that Peregrines should fly faster in level powered and gliding flight, but incur greater fuel costs in terms of both time and distance flown. Peregrines should glide less efficiently and be restricted in their ability to soar in thermals. These predictions were compared with observations of Peregrines and Lanners under uniform environmental conditions, and mostly were confirmed. Peregrines flew faster but for less time, flapped more and soared in thermals less than Lanners. Theoretically, Peregrines should tend more towards sedentary perch hunting than Lanners, and be more habitat selective as a result. Observations and distributional data from South Africa corroborate this. Form and functional differences in these two falcons are relatable to differences in foraging mode, distribution and abundance. I suggest that similar inferences may be drawn from morphological comparisons of other large falcons to provide proximal explanations for broad-scale patterns of distribution.

The foraging behaviour and ecology of animal-eating bats

The results of recent studies of the foraging behaviour of animal-eating bats are considered in this review. The advent of small (&lt; 1 g) radio transmitters has made it possible to collect data on individual variations in foraging behaviour for species with body mass over 15 g. These data can be combined with those from wing morphology and echolocation call design to assess the flexibility achieved by some bats. The information concerning bats can be placed in a broader perspective by considering it in the light of current ideas about foraging theory. In this review, information about bat foraging is considered in the context of structural and functional features, the former relating to bats' access to habitats of different complexity and the latter to their behavioural responses. Mechanical features involving wing morphology and perceptual features, such as the ability of echolocating bats to deal with clutter, combine to influence the behavioural flexibility of individuals. This, in turn, affects access to prey and patterns of community structure. Bats relying on airborne prey appear to be limited to small prey items, whereas those hunting nonairborne targets may take much larger prey. Variation in individual behaviour means that terms such as gleaning, perch hunting, piscivory, and carnivory do not accurately define the foraging of animal-eating bats. Morphological and behavioural data suggest that sympatric animal-eating bats of similar size will show considerable overlap in prey taken and in patterns of habitat use.

Foraging behavior and echolocation of wild horseshoe bats Rhinolophus ferrumequinum and R. hipposideros (Chiroptera, Rhinolophidae)

1. Echolocation and foraging behavior of the horseshoe bats Rhinolophus ferrumequinum and R. hipposideros feeding under natural conditions are described. 2. The calls of both species consisted predominantly of a long CF segment, often initiated and terminated by brief FM sweeps of substantial bandwidth. 3. R. hipposideros typically flew close to vegetation, and fed by aerial hawking, gleaning and by pouncing on prey close to the ground. R. hipposideros called with a CF segment close to 112 kHz which is the second harmonic of the vocalization; its calls included low intensity primary harmonics, and had prominent initial and terminal FM sweeps of considerable bandwidth. When searching for prey on the wing it had longer interpulse intervals than R. ferrumequinum, but emitted shorter pulses at a higher repetition rate; overall it had a similar duty cycle to R. ferrumequinum. 4. R. ferrumequinum, calling with a CF segment close to 83 kHz, also used harmonics other than the dominant secondary in its calls, and modified its echolocation according to ecological conditions. This species showed certain parallels with R. rouxi of Asia. It was observed feeding by aerial hawking and by flycatching. When scanning for prey from a perch (perch hunting), calls were of shorter duration, and interpulse intervals were on average longer, than when bats were flying. Mean duty cycle was longer in flight, and the bandwidths and frequency sweep rates of the FM segments in the calls increased in comparison with perched bats. 5. FM information may facilitate determination of target range and the location and nature of obstacles; it may also be involved in the interpretation of echoes and the detection of moving targets among clutter. The rising FM sweep initiating the call in both species when flying (and to a lesser extent perch hunting) in the wild must have a significant adaptive role, and should be considered an essential component of the call; rhinolophids should be termed ‘FM/CF/FM’ bats.

Foraging Strategies of American Kestrels During Breeding

Of the two hunting methods most commonly used by American Kestrels (Falco sparverius), hovering cost more but yielded more per unit time perch—hunting. Birds increased their use of hovering relative to other hunting methods as wind speed increased (lowering the energetic cost of hovering flight), and as the number and size of their dependents rose. Perch—hunting kestrels left a foraging site shortly after reward rate fell below the average reward rate for all sites, a behavior consistent with maximizing net energy intake when travel costs are considered. Larger prey were preferentially transported to the mate or young, as predicted by central place foraging models. In three pairs, males provides females during egg—laying, incubation, and brooding, but one pair foraged individually and shared incubation. Each pair foraged in ways that minimized the costs of energy acquisition in its particular situation.

ECOLOGY AND BEHAVIOUR OF THE GYMNOGENE

Summary Thurow, T. L. & Black, H. L. 1981. Ecology and behaviour of the Gymnogene. Ostrich 52:25-35. Observations were made on two pairs of Gymnogenes Polyboroides typus throughout most of the 1978 breeding season. The nests were attended by at least one of the pair 98% of the daytime, with both parents participating in the 35–36 day incubation period. Changes in facial colour and exchange of nesting material were apparently stimuli necessary for cooperative nest relief. After chicks had hatched, the male returned to the nest only to deliver prey to the female. Changes in the male's facial colour also accompanied food transfers. By the fourth week the female began hunting and the male no longer approached the nest but transferred prey to her away from the nest site. Four general hunting methods were used: low soaring, high soaring, perch hunting and canopy-ground hunting. Of 85 prey items identified during this study 33% were birds (primarily nestlings), 41% reptiles and amphibians, 15% small mammals and ...