HUNTING BEHAVIOUR OF THE CHEETAH IN THE SERENGETI NATIONAL PARK, TANZANIA

Eighty-nine per cent, of 136 cheetah kills in the Serengeti National Park consisted of Thomson's gazelles, the most abundant and readily available species in the size category (60 kg or less) preferred by the cheetah. Fifty-four per cent, of the Thomson's gazelle kills were subadult; among the adults all age classes were represented. One female cheetah captured 24 Thomson's gazelles in 26 days, a killing rate of 10 kg/day. The actual food intake of this female was about 4 kg/day. The hunting success of cheetah pursuing large subadult and adult Thomson's gazelles was about 50 per cent. The hunting methods–including the various means of approaching prey–are described as are the typical ways of killing and feeding. Twelve per cent, of the cheetah kills were appropriated by lions and hyaenas.     

Landscape scale, heterogeneity, and the viability of Serengeti grazers

Species persistence can be threatened by substantial temporal variation in food resources over time. On the other hand, spatial heterogeneity in resources at the landscape scale might allow mobile consumers to compensate for temporal variability in resource availability at the local scale. We evaluated this hypothesis, using an extensive data set on foraging, grass growth, and movement by Thomson's gazelles living on the Serengeti Plains. Here we show that modelled populations of Thomson's gazelles can only persist under Serengeti conditions in the face of observed levels of rainfall stochasticity by making adaptive movements to take advantage of ephemeral spatial distributions of food resources. More importantly, our models suggest that Thomson's gazelles in Serengeti require unrestricted access to relatively large areas of grassland (> 1600 km²) to guarantee long‐term persistence, particularly when there is positive spatial autocorrelation in resource abundance, as is the case in Serengeti. If this proves to be true for other species and/or other systems, then understanding of complex behavioural responses to spatially and temporally heterogeneous food supplies may be essential to successful conservation of grazing herbivores.     

Migration patterns of Thomson's gazelles and cheetahs on the Serengeti Plains

Monthly changes in abundance of Thomson's gazelles at 142 locations on the Serengeti Plains are presented over a 3½ year period. Numbers of gazelles on the eastern plains were strongly correlated with rainfall, whereas numbers in the central and western plains appeared to be related to other variables. Movements of female cheetahs and non-resident male cheetahs corresponded closely to the movements of Thomson's gazelles but those of resident male cheetahs remained relatively independent of the gazelle migration.     

The impacts of burning on Thomson's gazelles', Gazella thomsonii,vigilance in Serengeti National Park,Tanzania

Alterations to habitats that increase the distance at which prey can detect predators can decrease the risk of predation. In grasslands, burning may have this effect for mammalian herbivores by decreasing vegetation height, potentially making burned areas safer habitats. However, few studies have tested the impacts of burning on the perceived predation risk of herbivores. Vigilance can be used as a measure of habitat safety and therefore should be lower in burned areas than unburned areas. We tested the impacts of prescribed burning on vigilance by Thomson's gazelles in Serengeti National Park, Tanzania. Both individual vigilance, proportion of time an individual spends looking, and group vigilance, proportion of a group looking, of Thomson's gazelles was observed in burned and unburned areas before and after presenting a model cheetah to each group. Surprisingly, both individual and group vigilance was the same in both habitats pre‐ and post‐cheetah addition and removal. This is despite the fact that both vegetation height and biomass were lower in burned areas than unburned areas. Thus, it does not appear that Thomson's gazelles perceive burned areas to be safer habitats than unburned areas.     

Breeding of the lappet-faced and white-headed vultures (Torgos tracheliotus Forster and Trigonoceps occipitalis Burchell) on the Serengeti Plains, Tanzania

The lappet-faced and white-headed vulture nests in a 1636 km² study area on the Serengeti Plains were kept under observation from June 1972 to August 1973. Active nests were inspected from a light aircraft at intervals of approximately 2 weeks. The inverse nesting densities were estimated as 43 km²/pair for the lappet-faced vulture and 409 km²/pair for the white-headed vulture. Nests were built of sticks in exposed sites on the crowns of trees, Acacia tortilis being the most popular species. Where the previous history was known, 44% of lappet-faced vulture nests were newly constructed, and the rest re-used from the previous year. The incubation period was about 55 days and the fledging period about 100 days in both species. Juveniles continued to frequent their nests after they could fly, sometimes for several months. Most lappet-faced vultures laid their eggs in April-May, the white-headed vultures in June-August. This means that the lappet-faced vultures raised their young during the dry season, when Grant's and Thomson's gazelles were the only animals present in any numbers on the plains. By contrast, the Ruppell's griffons nesting in the nearby Gol Escarpment colony raise their young during February-May, when the wildebeest and zebra herds are normally on the plains. The survival rate of lappet-faced vultures from laying to fledging was about 40%. The chicks are thought to be vulnerable to predation by tawny eagles, and one was known to have been killed by a leopard. Three adult vultures were killed on their nests, from unknown causes. Food remains from lappet-faced vulture nests showed a heavy preponderance of Grant's and Thomson's gazelles in all cases, with golden jackal the next most commonly occurring species. No food remains were obtained from white-headed vulture nests. The possibility of using aerial counts of vulture nests as an indicator of productivity is discussed.     

The functions of stotting in Thomson's gazelles: some tests of the predictions

Stotting in Thomson's gazelles (Gazella thomsoni) was found to have a negligible time cost in slow flights and it was normally shown in safe situations when prey were unlikely to be captured. Despite its probable energy cost and time cost during fast flights there was no evidence to show that, once a chase occurred, stotting gazelles were caught more or less often than gazelles that did not stott.Eleven hypotheses concerning the benefits of stotting were tested using a number of predictions about the stotting individual, its conspecifics and the predator (usually cheetahs), some of which were pertinent to several hypotheses. Although a number of hypotheses were supported by some of the predictions, most were refuted by one or more pieces of evidence. Only two were satisfactorily supported by all of them: stotting appears to inform the predator that it has been detected, but it does not invite or deter the predator from pursuing the gazelle. In neonate Thomson's gazelles, stotting probably has a different function, it informs the mother that the neonate has been disturbed and is in need of defence. In addition, mothers whose neonates escaped capture by cheetahs stotted significantly more during the attempt than mothers whose neonates were caught. Hypotheses concerning the prey signalling its health, startling or confusing the predator; group cohesion; anti-ambush behaviour; play in young animals; warning of conspecifics; and pursuit invitation or deterrence were dismissed by data presented here.     

Seroprevalence of Sheep and Goat Pox,Peste Des Petits Ruminants and Rift Valley Fever in Saudi Arabia

Sheep and goat pox, peste des petits ruminants and Rift Valley fever are important diseases of small ruminant livestock. Sheep and goat pox, along with peste des petits ruminants, are endemic throughout most of Africa, Asia and the Middle East. Whereas Rift Valley fever is endemic in Africa, outbreaks in the Middle East have been reported over the past decade, including the Arabian Peninsula. Saudi Arabia is a major importer of livestock, and understanding the prevalence of these viral infections would be useful for disease control. In this study, sera from sheep and goats were collected from 3 regions in Saudi Arabia. They were evaluated for antibodies specific to sheep and goat pox, peste des petits ruminants and Rift Valley fever by virus neutralization assays. To the best of our knowledge, this is the first study to evaluate the seroprevalence of these viruses in sheep and goats.     

A seasonal feast: long-term analysis of feeding behaviour in the spotted hyaena (Crocuta crocuta)

The feeding behaviour of the Talek clan of spotted hyaenas in the Masai Mara National Reserve, Kenya, was monitored continuously for 7 years. Talek hyaenas adapted to large temporal variations in prey abundance by being opportunistic predators. During the first half of the year, the hyaenas fed on resident ungulates, and their diet consisted mainly of topi and Thomson's gazelles. Upon arrival of the migratory herds of wildebeest and zebra from the Serengeti, Talek hyaenas switched to feeding on the wildebeest which provided them with a superabundance of food for about 3 months. After the migratory animals returned to the Serengeti, Talek hyaenas experienced a period of reduced prey abundance due to the temporary dispersion of resident ungulates. At this time hyaenas hunted the few remaining wildebeest, and also increased their use of the remaining resident animals. Although Talek hyaenas were generally opportunistic in their feeding behaviour, they did exhibit clear dietary preference for larger prey species, particularly wildebeest. Finally, carrion comprised only 5% of the biomass consumed by Talek hyaenas, the lowest proportion of carrion in the diet of any Crocuta population studied to date.     

Length–weight relationships for eight fish species from the Ravi River,north‐western India

Length–weight relationships (LWRs) were evaluated for Badis badis (n = 25), Sperata seenghala (n = 26), Labeo gonius (n = 34), Rasbora rasbora (n = 30), Bagarius bagarius (n = 24), Gagata cenia (n = 27), Glyptothorax stoliczkae (n = 24) and Channa orientalis (n = 28) from the Ravi River tributary in North India. Altogether 218 samples of eight species were obtained between May and November 2014 using cast nets and gill nets. LWRs for these species were unknown to FishBase, and new maximum lengths were recorded for two of these species.     

Enzymatic reporting of peste des petits ruminants virus genes ligating two specific probes on nanoparticles

An alternative strategy for the detection of nucleic acid derived from peste des petits ruminants virus was developed omitting amplification. The assay is based on two probes complementary to the target sequences, one conjugated to magnetic microparticles the second to gold nanoparticles labeled with horseradish peroxidase. In the presence of target gene the two particles ligate via the probes and the complex can be magnetically separated. Applying substrate and chromogen a color reaction results for a positive case. Under optimized conditions, the approach had a linear detection range from 10 fM to 1 μM for ssDNA corresponding to an RNA low detection limit of 17.6 ng/μl. The quick performance (45 min) and not requiring expensive instrumentations offer a new way of detecting nucleic acids for the clinical diagnosis in our case for peste des petits ruminants virus.     

Effects of azaperone and haloperidol on the stress response of drive-net captured Iberian ibexes (<Emphasis Type="Italic">Capra pyrenaica</Emphasis>)

The physical capture of wild ungulates is performed for different purposes when anesthesia in field conditions is not possible or advisable. The use of tranquilizers may contribute to improved welfare of captured animals. This study aimed to evaluate the effect of azaperone and haloperidol on the stress response of Iberian ibex (Capra pyrenaica) through the evaluation of physiological, hematological, and serum biochemical parameters. Thirty-five Iberian ibexes were drive-net captured and randomly injected with azaperone (0.52 ± 0.07 mg/kg intramuscularly (IM); n = 10), haloperidol (0.17 ± 0.04 mg/kg IM; n = 10), or saline (0.5 mL IM; n = 15) and physically restrained for 3 h. The variability of heart rate was lower in the azaperone-treated ibexes, suggesting a calming effect, and erythrocyte and biochemical parameters indicated vasodilation, splenic sequestration, hemodilution, improvement of renal perfusion, and a protective effect on muscle as a result of smooth muscle relaxation induced by azaperone. Haloperidol showed poorer results, maybe due to insufficient dosage. These results support the suitability of using azaperone in capture operations of Iberian ibex in order to reduce stress and prevent its adverse effects.     

Length‐weight relationships for five freshwater fish species from the Utinga State Park,Northeast Amazon,Brazil

Length–weight relationships (LWR) were estimated for five most abundant fish species occurring in the Utinga State Park within the metropolitan area of Belém, State of Pará, Northern Brazil. Data were obtained from specimens of Curimata knerii (n = 75), Gasteropelecus levis (n = 54), Hemigrammus rodwayi (n = 82), Hyphessobrycon bentosi (n = 69), and Pristobrycon calmoni (n = 76) collected in July 2013 with seines (1.5 mm mesh), sieves (1 mm mesh), and gill nets (40–120 mm mesh) in the main waterbodies. All LWRs are novel for science, increasing knowledge on biological information of the Neotropical freshwater fish.     

Improving our understanding of demographic monitoring: avian breeding productivity in a tropical dry forest

The ratio of juvenile to adult birds in mist‐net samples is used to monitor avian productivity, but whether it is a “true” estimate of per capita productivity or an index proportional to productivity depends on whether capture probability is not age‐dependent (true estimate) or age difference in capture probability is consistent among years (index). Better understanding of the processes affecting age‐ and year‐specific capture probabilities is needed to advance the application of constant‐effort mist‐netting for monitoring and conservation, particularly in many tropical settings where capture rates are often low. We ranked members of the avian community by capture frequencies, determined if temporary emigration influenced the availability of birds to be captured, and assessed the distribution of birds relative to mist‐nets and the parity between capture‐based productivity estimates and number of fledglings in nest plots in a tropical dry forest in Puerto Rico in 2009 and 2010. Few captures characterized the community of 25 resident species and, when estimable, capture probabilities were low, particularly for juveniles (typically < 0.1). Negative trends in capture probability, temporary emigration, and the distribution of birds suggest that avoidance of mist‐nets influenced capture rates in our study. Increasing mist‐net coverage or moving mist‐nets between sampling periods could increase capture rates. The number of fledglings observed in nest plots (25 ha/plot) did not correlate well with capture‐derived estimates (20 ha/net stations), suggesting the presence of immigrants or failure to find all nests. Our results suggest that indices of breeding productivity from mist‐netting data may track temporal changes in productivity, but such data likely do not reflect “true” productivity in most cases unless age‐specific differences in capture probability are incorporated into estimates. Pilot studies should be conducted to evaluate capture rates and the spatial extent sampled by mist‐nets to improve sampling design and inferences before informing decisions.     

Biological parameters and current status of European eel (Anguilla anguilla Linnaeus, 1758) from Asi River,Northeastern Mediterranean region,Turkey

The biological characteristics of eels from the Asi River, Turkey, were assessed between December 2017 and November 2018. Eels were sampled monthly using fyke nets (operated by professional fishermen), yielding a total of 509 specimens. Total length and weight were measured, sex, age and maturity stages (silver or yellow eel) were determined. Catch Per Unit Effort (CPUE) was calculated for both biomass per unit effort and numbers caught on a monthly and annual basis. The length-weight relationships (LWRs) of silver and yellow eel was W = 0.009*TL^3.22 (n = 262) and W = 0.0106*L^3.09 (n = 247), respectively. The age of the sampled fish ranged from year class II to VI. Von Bertalanffy growth parameters were estimated as L_∞=69.25 cm, K = 0.43 1/year, t₀= −0.41 and phi prime index ( ǿ )= 3.31 for all samples. The overall eel fishing mortality rate (F) was 0.31 year^-1, and the exploitation and survival rates of silver stage eels were estimated with 30% and 39%, respectively.     

Capturing American White Ibises in urban South Florida using two novel techniques

As many wildlife species, including wading birds, adapt to anthropogenic landscapes and, in some cases, exhibit altered behaviors, studies that involve capturing birds may require new methods better suited for use in urban areas and to accommodate altered animal behavior. We developed two novel techniques, a leg lasso and flip net, for capturing American White Ibises (Eudocimus albus) in urban environments in southern Florida, and also used a traditional technique (mist‐nets) in non‐urban wetland habitats. The flip net and leg lasso were developed to capture White Ibises habituated to the presence of humans. Ibises were captured in urban and wetland environments from October 2015 to August 2017 in Palm Beach, Broward, and Lee counties, Florida. We captured 6.0 ± 13.5 ibis/h with the flip net, 1.6 ± 0.8 ibis/h with the leg lasso, and 0.5 ± 2.6 ibis/h with mist‐nets. We captured larger (higher mass to tarsus length ratio) birds using the flip net and leg lasso than using mist‐nets, and captured more males with leg lassos than with other two techniques. The novel techniques we used are efficient, cost effective, easy to use, and also potentially useful for capturing other species of birds. Leg lassos and flip nets are also safe to use in populated areas for both birds and humans.     

Neotropical bats in the canopy: diversity,community structure,and implications for conservation

We compare results of parallel ground and canopy netting of bats (Microchiroptera) in three adjacent forest sites near Belém, Brazil, to document possible differences in vertical distribution of species. We caught 1871 individuals representing 49 species of three families (Emballonuridae, Phyllostomidae, Vespertilionidae). Capture effort, totaling 1955.5 mistnet hours in several cycles over a two-year period, was similar for ground and canopy nets. The canopy rigs yielded more species (n = 41) than the ground nets (n = 35), but both samples were characterized by rank abundance curves with similar shape and with a dominance of frugivores (Phyllostomidae). Nearly half (n = 24) of the species were captured in numbers too small (n < 6) to allow firm classification, but differences in capture frequencies of some of the better-sampled species in high and low nets reveal vertical stratification. Species-specific differences in diet, foraging strategies, roost sites, and sampling bias contribute to this pattern. As a result of the differential use of space among bats, alterations of forest structure are likely to result in changes in structure and function of local bat communities, but our limited knowledge of natural history and ecology of many species limits definition of changes. We see a critical need for further research into the extent to which habitat complexity influences species richness and abundance of bats. This information is especially important in view of the need to develop and apply conservation-oriented programs to maintain biodiversity. A review of recent improvements in techniques for inventorying bats shows that a combination of methods, including mistnetting and acoustic monitoring, is mandatory for such studies.     

Genetic divergence over small geographic scales and conservation implications for Commerson's dolphins (Cephalorhynchus commersonii) in southern Argentina

Cephalorhynchus commersonii is distributed in the nearshore coastal waters of South America, and thus is particularly vulnerable to bycatch in coastal nets and trawls. Our study documents genetic structure in presumed Commerson's dolphin subpopulations along the southern Argentina coastline, from the Ría Deseado in the north to Ría Gallegos in the south, and focuses on the potential for depletion in the apparently more heavily impacted Ría Gallegos area. Only two control region (423 bp) haplotypes were shared among all these locations (out of 11 identified), and striking differences in haplotype frequencies between areas are apparent. AMOVA analysis, using mitochondrial sequence data, indicates significant population subdivision (overall F_ST= 0.21, P < 0.001) between Ría Deseado (n= 8), Bahía San Julián (n= 11), Ría Gallegos (n= 31), and a small sample of dolphins from the captive colony at San Diego Seaworld (n= 7) derived from animals originally captured in the Strait of Magellan. Comparisons based on haplotypic distances indicated relatively strong differences between regions (Φ_ST= 0.30, P < 0.001). This research provides the first indication of reduced gene flow and genetic differentiation within local subpopulations of Commerson's dolphins, along a relatively small stretch of coastline.     

Estimating mortality rates among passerines caught for ringing with mist nets using data from previously ringed birds

Mist netting is the most commonly used method for catching birds for scientific ringing, but despite decades of use, there have been few attempts to quantify the associated potential risks to the individuals caught. Any incidence of mortality through capture and handling, however low, is of potential ethical concern and may also introduce biases into the data. We estimate the mortality rate associated with capture of previously ringed (recaptured) passerines from the British and Irish Ringing Scheme (c. 1.5 million records) caught using mist nets. The importance of species, age, mass, month, time, previous captures, and an index of predator occurrence was tested using generalized linear mixed‐effects models. The average mortality rate was 0.0011, most of which was reported to occur before the individuals had been extracted from the nets (c. 70% of incidents). Juveniles appeared to be at higher risk and the incidence of predation from mist nets was seasonal, with increased risk during the winter. Species differed in their reported mortality rates with the apparent risk being greatest for Chiffchaff Phylloscopus collybita (0.0029) and Bullfinch Pyrrhula pyrrhula (0.0027). To improve our understanding (and hence minimize risk in future), we recommend collecting more complete data on incidences of mortality, and also injuries; exercising increased care when the species we have identified as being at greater risk are likely to be captured, and ensuring there are robust procedures for the checking of nets (as most reported incidents of mortality occur before handling). We also recommend that all Ringing Schemes should collate and make available data on capture‐related mortality. Overall rates of mortality associated with capture, although, were low and support the use of mist netting as a safe capture technique, without undue bias from mortality, when used by appropriately trained individuals.     

Length‐weight relationships for three species of common scorpaenoids from Singapore

This study provides length‐weight relationships (LWR) for three common marine species collected from Singapore, a small tropical island country in southeast Asia, where monthly collections using seine netting and fish trapping were performed at six sites from January to December 2010. The LWRs of these three species were BW = 0.0348 SL^3.002 (n = 305, r² = .9747) for Paracentropogon longispinis, BW = 0.0315 SL^3.039 (n = 104, r  = .9798) for Trachicephalus uranoscopus and BW = 0.0651 SL^3.021 (n = 70, r² = .9601) for Synanceja horrida respectively.     

Crossbow‐netting: a new method for capturing shorebirds

Capturing shorebirds during the non‐breeding season can be challenging because they are usually scattered over wide‐open intertidal areas while foraging and are sensitive to human disturbance at roosts where they gather during high tide in large vigilant flocks. Several techniques are available for capturing shorebirds, but, for a study of stopover ecology, we needed a method that would allow us to capture Dunlins (Calidris alpina) on a regular basis at high‐tide roosts during the day (ruling out mist‐nets), did not require the use of gun‐powder (ruling out cannon‐nets), and that would deploy a net faster than clap nets, whoosh nets, and wilsternets. Therefore, we developed a new method to capture shorebirds where a crossbow is used to pull a mist‐net over flocks of roosting birds. We tested this technique in four habitats (saltpans, salt marshes, beaches, and mudflats) in the Tagus estuary, Portugal, and captured over 380 birds representing eight different species. Advantages of this technique compared to other methods (e.g., mist‐nets, clap‐ and whoosh nets, and cannon‐nets) include (1) portability, (2) ease of set up, (3) minimal disturbance of birds near the capture area, and (4) no explosive materials are needed. Our results suggest that crossbow‐netting is a safe and useful capture technique, especially for studies requiring the capture of small numbers of birds on a regular basis.