Wet-season effects on the distribution of juvenile pigeye sharks, Carcharhinus amboinensis, in tropical nearshore waters

Tropical nearshore environments are highly dynamic systems owing to extreme freshwater flow and flooding episodes that occur in wet-season months. We hypothesised that juvenile sharks in tropical nearshore waters respond to seasonal freshwater inflow by moving away from areas of strong flow. An array of fifty-eight acoustic receivers deployed in Cleveland Bay, north Queensland, Australia, passively tracked thirty-two juvenile pigeye sharks, Carcharhinus amboinensis, throughout two wet seasons from 2008 to 2010. Influences associated with wet seasons appeared to play a role in habitat use by juvenile C. amboinensis in this region. Home ranges and distribution of individuals showed distinct changes, with individuals moving north away from sources of freshwater inflow during high flows. The location of individuals within the bay was strongly influenced by freshwater inflow in both years. Although juvenile C. amboinensis moved in response to freshwater inflow, home-range sizes remained stable, and the amount of space individuals used did not change in relation to freshwater inflow. By defining the response of juvenile sharks to highly variable freshwater flow events, this research provides useful information for understanding species behaviour in a dynamic and changing climate, and contributes towards effective management of tropical river systems.

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Carbon-Isotope, Diatom, and Pollen Evidence for Late Holocene Salinity Change in a Brackish Marsh in the San Francisco Estuary

Quaternary Research ◽

10.1006/qres.2000.2199 ◽

2001 ◽

Vol 55 (1) ◽

pp. 66-76 ◽

Cited By ~ 67

Author(s):

Roger Byrne ◽

B. Lynn Ingram ◽

Scott Starratt ◽

Frances Malamud-Roam ◽

Joshua N. Collins ◽

...

Keyword(s):

San Francisco ◽

High Salinity ◽

Carbon Isotopic Composition ◽

Brackish Marsh ◽

San Francisco Estuary ◽

Freshwater Inflow ◽

Water Diversion ◽

Freshwater Flow ◽

Low Salinity ◽

Carbon Isotopic

AbstractAnalysis of diatoms, pollen, and the carbon-isotopic composition of a sediment core from a brackish marsh in the northern part of the San Francisco Estuary has provided a paleosalinity record that covers the past 3000 yr. Changes in marsh composition and diatom frequencies are assumed to represent variations in freshwater inflow to the estuary. Three periods of relatively high salinity (low freshwater inflow) are indicated, 3000 to 2500 cal yr B.P., 1700 to 730 cal yr B.P., and ca. A.D. 1930 to the present. The most recent period of high salinity is primarily due to upstream storage and water diversion within the Sacramento–San Joaquin watershed, although drought may also have been a factor. The two earlier high-salinity periods are likely the result of reduced precipitation. Low salinity (high freshwater flow) is indicated for the period 750 cal yr B.P. to A.D. 1930.

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Agricultural crops in the diet of bearded capuchin monkeys, Cebus libidinosus Spix (Primates: Cebidae), in forest fragments in southeast Brazil

Revista Brasileira de Zoologia ◽

10.1590/s0101-81752008000100006 ◽

2008 ◽

Vol 25 (1) ◽

pp. 32-39 ◽

Cited By ~ 38

Author(s):

Carlos Henrique de Freitas ◽

Eleonore Z. F. Setz ◽

Alba R. B. Araújo ◽

Nivar Gobbi

Keyword(s):

Fruit Production ◽

Dry Season ◽

Southeastern Brazil ◽

Capuchin Monkeys ◽

Home Ranges ◽

Forest Fragments ◽

Wet Season ◽

Plant Matter ◽

Wide Range ◽

Cebus Libidinosus

Capuchin monkeys occupy a wide range of habitats where they feed on fruits, arthropods, and vertebrates. Their large home ranges (80-900 ha) suggest that living in forest fragments may challenge their adaptability. We identified and quantified the main food items of Cebus libidinosus Spix, 1823 in forests fragments (100 ha) in southeastern Brazil. We recorded the feeding activities of two groups using scan sampling over a 13-month period. The diet was composed of fruits, crops, animal prey, seeds, plant matter and undetermined. Fruit was eaten more in the wet season than in the dry season, and maize and sugar cane consumption peaked in the early dry season. The proportion of fruit in the diet was positively correlated with fruiting intensity of zoochorous trees. The plant diet included 54 species, with maize, Rhamnidium elaeocarpus, Acrocomia aculeata, Guazuma ulmifolia and Cariniana, being most important. Although dietary composition and diversity were similar to capuchins in larger forest fragments, feeding on crops attained higher percentages at times when zoochorous fruit production was low in fragments.

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Fish assemblage in a dammed tropical river: an analysis along the longitudinal and temporal gradients from river to reservoir

Neotropical Ichthyology ◽

10.1590/s1679-62252010000300004 ◽

2010 ◽

Vol 8 (3) ◽

pp. 599-606 ◽

Cited By ~ 22

Author(s):

Bianca de Freitas Terra ◽

Alex Braz Iacone dos Santos ◽

Francisco Gerson Araújo

Keyword(s):

Fish Assemblage ◽

Transitional Zone ◽

Assemblage Structure ◽

Fish Assemblage Structure ◽

Wet Season ◽

Tropical River ◽

Longitudinal Gradient ◽

Species Overlap ◽

Seasonal Flow ◽

Paraíba Do Sul River

We analysed changes in the fish assemblage structure along a longitudinal gradient of the Paraíba do Sul River and Funil Reservoir. We tested the hypothesis that shifts from lotic to lentic environment affect the richness and structure of the assemblage which are modulated by seasonal rainfall changes. Standardised monthly samplings were carried out from October 2006 to September 2007 in four zones: 1) river upstream from the reservoir; 2) upper part of the reservoir; 3) lower part of the reservoir, and 4) river downstream from the reservoir. Fishes were caught using gillnets deployed for 15 hours. We collected a total of 4550 specimens, representing 35 species and 5 orders. The highest richness and diversity were recorded in zone 2, the transitional zone between river and reservoir. In this ecotone, lotic and lentic species overlap. Greater abundance and biomass was recorded in the river upstream from the reservoir (zone 1); however, there are no differences between the zones in the structure of assemblages during the wet season. During the dry season, the assemblage structure is more differentiated between zones, although no differences in abundance and biomass occur. The seasonal flow of the river is the major driving factor to influence the fish assemblage structure along the longitudinal gradient from the river to the reservoir.

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Spatial ecology of slatey-grey snakes (Stegonotus cucullatus, Colubridae) on a tropical Australian floodplain

Journal of Tropical Ecology ◽

10.1017/s0266467405002671 ◽

2005 ◽

Vol 21 (6) ◽

pp. 605-612 ◽

Cited By ~ 27

Author(s):

Gregory P. Brown ◽

Richard Shine ◽

Thomas Madsen

Keyword(s):

Spatial Ecology ◽

Home Range Size ◽

Home Ranges ◽

Wet Season ◽

Tree Roots ◽

Long Distance ◽

Dry Tropics ◽

Forested Areas ◽

Extensive Information ◽

Soil Cracks

The extent, sequence, synchrony and correlates of diel displacements by animals can provide powerful insights into the ecological and social factors that shape an organism's day-to-day activities, but detailed data on spatial ecology are available for very few tropical taxa. Radiotelemetric monitoring of 25 slatey-grey snakes (Stegonotus cucullatus) on a floodplain in the Australian wet-dry tropics for periods of 40 to 355 d (mean=195 d, 136 locations per snake) provided extensive information on habitat use, movement patterns and home range size of these large slender-bodied colubrids. All radio-tracked animals were nocturnal, sheltering by day in soil cracks and beneath tree roots and debris. Snakes did not appear to move between 61% of successive locations and timing of movements was not synchronized among snakes. Most displacements were small (<50m), with males moving further and more often than did females. However, nesting females made occasional long-distance movements, travelling 100–400m to forested areas to oviposit but then returning to their usual home ranges. Snakes of both sexes moved further and more often during the wet-season than the dry-season. Snakes typically moved on a few successive nights then remained sedentary for the next few days, apparently reflecting cessation of activity as soon as a meal was obtained. Home ranges were small (2.9–7.4 ha) and most snakes remained in the same area throughout the year, providing a strong contrast in this respect to the large and seasonally dynamic home ranges of sympatric acrochordid and pythonid snakes.

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Sexual and environmental variation in the space requirements of the Critically Endangered geometric tortoise, Psammobates geometricus

Amphibia-Reptilia ◽

10.1163/156853812x634071 ◽

2012 ◽

Vol 33 (2) ◽

pp. 185-197 ◽

Cited By ~ 9

Author(s):

Margaretha Hofmeyr ◽

Ulric van Bloemestein ◽

Brian Henen ◽

Craig Weatherby

Keyword(s):

Home Range ◽

Habitat Degradation ◽

Space Use ◽

Home Range Size ◽

Home Ranges ◽

Convex Polygons ◽

Wet Season ◽

Mating Opportunities ◽

Space Requirements ◽

Nesting Season

Psammobates geometricus has a limited distribution in the southwestern Cape, South Africa, where it occurs in small habitat fragments separated by agricultural and urban developments. Space use and its determining factors thus represent critical information for the effective conservation of this species. We used radiotelemetry and thread-trailing to study the movement patterns and space use of geometric tortoises over an annual cycle, and estimated home ranges with minimum convex polygons and fixed-kernel methods. Home range size of geometric tortoises showed large inter-individual variation, and for females, a positive relationship to body size. Females, the larger sex, had larger home ranges and mean daily displacements than males had. Female space use was high through most of the year, except in the wet season, when food was abundant, temperatures relatively low, and soft soils allowed easy nesting. Males used more space and displaced further in the non-nesting than nesting season, perhaps to optimise mating opportunities in the non-nesting season before females ovulate. Home ranges were more elongate and overlapped more in fallow fields than in natural vegetation, suggesting that habitat degradation alters home range structure. The space geometric tortoises used for their annual activities ranged from 1.02 to 44.85 ha. The large home ranges and effects of habitat degradation should influence the size of reserves, and the destiny of geometric tortoises in small habitat fragments.

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Home ranges and movement schedules of sympatric bridled nailtail and black-striped wallabies

Wildlife Research ◽

10.1071/wr9960547 ◽

1996 ◽

Vol 23 (5) ◽

pp. 547 ◽

Cited By ~ 17

Author(s):

M Evans

Keyword(s):

Home Range ◽

Home Range Size ◽

Range Size ◽

Home Ranges ◽

Radio Tracking ◽

Wet Season ◽

Seasonal Differences ◽

Dry Seasons ◽

Species Movement ◽

Wet And Dry Seasons

Home ranges and movement schedules of sympatric bridled nailtail wallabies, Onychogalea fraenata, and black-striped wallabies, Macropus dorsalis, were studied during wet and dry seasons by radio-tracking. Home ranges of black-striped wallabies (91 ha) were much larger than those of bridled nailtail wallabies (40 ha). Home-range size differed between sexes for bridled nailtail wallabies (males, 59 ha; females, 26 ha), but not for black-striped wallabies. Intraspecific seasonal differences in home-range size were not significant. All home ranges included diurnal shelter habitat, although the preferred type of shelter habitat was different for each species. Movement schedules differed significantly between wet and dry seasons for black-striped wallabies (which made a higher frequency of longer-distance movements during the dry season than during the wet season), but not for bridled nailtail wallabies.

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Great Gray Owl home range and habitat selection during the breeding-season

The UW National Parks Service Research Station Annual Reports ◽

10.13001/uwnpsrc.2019.5745 ◽

2019 ◽

Vol 42 ◽

pp. 90-96

Author(s):

Katherine Gura ◽

Bryan Bedrosian ◽

Anna D. Chalfoun ◽

Susan Patla

Keyword(s):

Habitat Selection ◽

Home Range ◽

Breeding Season ◽

Resource Selection ◽

Home Range Size ◽

Breeding Habitat ◽

Home Ranges ◽

Effective Management ◽

Density Estimates ◽

Resource Requirements

Identifying resource requirements of under-studied species during key stages such as breeding is critical for effective management. We quantified breeding-season home-range attributes and habitat selection of adult Great Gray Owls across multiple spatial (home-range and within-home-range level) and temporal (nesting and post-fledging; day versus night) scales in western Wyoming, USA. In 2018 and 2019 we outfitted adult male owls (n = 18) with GPS remote-download transmitters and collected hourly location data throughout the breeding season (1 May – 15 September). Using 50% and 95% kernel density estimates (KDE), mean core area was 1.2 km2 and mean home-range size was 6.2 km2 (n = 16). Resource selection analyses incorporated both remotely-sensed and microsite data. We conducted microsite surveys at used and available points within 95% KDE home ranges using a stratified random sample design (n = 661). Determining home-range and breeding habitat requirements will improve density estimates and facilitate the effective management of Great Gray Owls and their habitat. We found differing patterns between habitat selection at the home-range and within-home-range scales. Featured photo by YNP on Flickr. https://flic.kr/p/SA17KT

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Phytoplankton composition and constraints to biomass in the middle reaches of an Australian tropical river during base flow

Marine and Freshwater Research ◽

10.1071/mf11111 ◽

2012 ◽

Vol 63 (1) ◽

pp. 48 ◽

Cited By ~ 15

Author(s):

S. A. Townsend ◽

M. Przybylska ◽

M. Miloshis

Keyword(s):

Rapid Growth ◽

Phytoplankton Biomass ◽

Dry Season ◽

Base Flow ◽

Nutrient Concentrations ◽

Phytoplankton Composition ◽

Tropical River ◽

Transport Time ◽

Tropical Australia ◽

High Flows

Under high flows, the biomass of riverine phytoplankton can be constrained by short transport times and advective losses. However, under slower flows and longer transport times, secondary factors and sometimes their interaction with flow may constrain phytoplankton biomass. To contribute to a wider understanding of the riverine conditions that constrain phytoplankton biomass, we tested the hypothesis that phytoplankton of the Daly River (tropical Australia) was constrained by transport time during dry-season base flow. The river is virtually undisturbed, with oligotrophic nutrient concentrations during the dry season. The most frequently occurring taxa were planktonic, rather than benthic, and dominated by the dinoflagellate Peridinium inconspicuum which has r-strategist traits that favour rapid growth in a nutrient-deficient environment. Our hypothesis was not supported because increased downstream loads of Chlorophyll a and the domination of P. inconspicuum inferred phytoplankton net growth. Instead, phytoplankton biomass was more likely to be nutrient-limited, although transport time may limit phytoplankton growth over some reaches and for specific taxa. The present study demonstrated that even in the fast-flowing middle reaches of a river (~0.4 m s–1), a population of phytoplankton can be sustained.

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Home-range and den use of the mahogany glider, Petaurus gracilis

Wildlife Research ◽

10.1071/wr98046 ◽

2000 ◽

Vol 27 (1) ◽

pp. 49 ◽

Cited By ~ 26

Author(s):

Stephen M. Jackson

Keyword(s):

Home Range ◽

Dry Season ◽

Home Ranges ◽

Adjacent Area ◽

Wet Season ◽

Male And Female ◽

Fragmented Habitat ◽

Significant Difference ◽

Socially Monogamous ◽

Males And Females

The home-range of the mahogany glider was estimated, and its social behaviour examined, by following radio-collared animals over a two-year period within an area of continuous habitat and an adjacent area of fragmented habitat. The average home range within the continuous habitat was 19.25 ha for males and 20.34 ha for females, with male and female pairs occupying a combined area of 23.15 ha. In contrast, the average home range in the fragmented habitat was 11.05 ha for males and 6.80 ha for females, with a combined home-range of male and female pairs being 11.60 ha. The average overlap of the home ranges of paired males and females was 85.9%, compared with approximately 11% for non-paired individuals, which suggests that mahogany gliders are socially monogamous. For a total of 46 nights on which gliders were considered to behave normally for the entire night, the average foraging distance was 1506 m (range 590–3420 m) with no significant difference between males and females in either the continuous or fragmented habitat. There was, however, a significant difference in the distance individuals travelled during different times of the year, with longer distances being travelled during late dry season/wet season and shorter distances during the early to mid dry season. Mahogany gliders also travelled further when there was a high availability of nectar and pollen than when there was lower availability. A total of 83 dens (tree hollows) were recorded for the mahogany glider, with the poplar gum, Eucalyptus platyphylla, forest red gum, Eucalyptus tereticornis, and Clarkson's bloodwood, Corymbia clarksoniana, being most used.

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Spatial ecology of lions in a small, semi-fenced park surrounded by dense human populations: the case study of Nairobi National Park, Kenya

Mammalia ◽

10.1515/mammalia-2020-0116 ◽

2021 ◽

Vol 85 (3) ◽

pp. 198-207

Author(s):

Francis Lesilau ◽

Stijn Verschueren ◽

Maarten van’t Zelfde ◽

Kees C. J. M. Musters ◽

Geert R. de Snoo ◽

...

Keyword(s):

National Park ◽

Spatial Ecology ◽

Time Of Day ◽

Capital City ◽

Human Populations ◽

Home Ranges ◽

Ranging Behavior ◽

Wet Season ◽

Buffer Zones ◽

Nairobi National Park

Abstract Human population growth near protected areas often results in detrimental edge effects for apex carnivores, such as the African lion. Urbanization leads to new scenarios of the human–lion conflict, thus understanding ranging patterns close to urban environments is crucial to inform future management strategies. We collected GPS data from 12 collared lions between 2014 and 2018 in Nairobi National Park, which borders the capital city of Kenya, Nairobi city. We estimated home ranges, calculated daily distance traveled and tested for differences between sex, season and pride. Additionally, we investigated how disturbance from Nairobi and surrounding human settlements affected space-use of lions, and tested for differences between sex, season and time of day. Lions showed restricted movements (4.5 km/day) and had small home ranges (49 km2). Male lions had larger ranges than females, but avoidance behavior of disturbed areas was similar. Lions took advantage during times of low human activity, i.e., during the night, to extend ranging behavior in search for resources. Risk for livestock depredation also increased during the wet season when lions roamed longer, more frequently, and deeper into the community lands. We recommend the establishment of buffer zones to maintain a viable lion population and reduced risk for conflict.

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