Use of Large Clear-Cuts by Wilson’s Warbler in an Eastern Canadian Boreal Forest

Wilson’s Warbler (Cardellina pusilla; WIWA) has been declining for several decades, possibly because of habitat loss. We compared occupancy of territorial males in two habitat types of Québec’s boreal forest, alder (Alnus spp.) scrubland and recent clear-cuts. Singing males occurred in clusters, their occupancy was similar in both habitats, but increased with the amount of alder or clear-cut within 400 m of point-count stations. A despotic distribution of males between habitats appeared unlikely, because there were no differences in morphology between males captured in clear-cuts vs. alder. Those results contrast with the prevailing view, mostly based on western populations, that WIWA are wetland or riparian specialists, and provide the first evidence for a preference for large tracts of habitat in this species. Clear-cuts in the boreal forest may benefit WIWA by supplying alternative nesting habitat. However, the role of clear-cuts as source or sink habitats needs to be addressed with data on reproduction.

Assessing the use of forest islands by parrot species in a neotropical savanna

Understanding the effect of habitat fragmentation is a fundamental yet complicated aim of many ecological studies. Beni savanna is a naturally fragmented forest habitat, where forest islands exhibit variation in resources and threats. To understand how the availability of resources and threats affect the use of forest islands by parrots, we applied occupancy modeling to quantify use and detection probabilities for 12 parrot species on 60 forest islands. The presence of urucuri (Attalea phalerata) and macaw (Acrocomia aculeata) palms, the number of tree cavities on the islands, and the presence of selective logging,and fire were included as covariates associated with availability of resources and threats. The model-selection analysis indicated that both resources and threats variables explained the use of forest islands by parrots. For most species, the best models confirmed predictions. The number of cavities was positively associated with use of forest islands by 11 species. The area of the island and the presence of macaw palm showed a positive association with the probability of use by seven and five species, respectively, while selective logging and fire showed a negative association with five and six species, respectively. The Blue-throated Macaw (Ara glaucogularis), the critically endangered parrot species endemic to our study area, was the only species that showed a negative association with both threats. Monitoring continues to be essential to evaluate conservation and management actions of parrot populations. Understanding of how species are using this natural fragmented habitat will help determine which fragments should be preserved and which conservation actions are needed.

The use of agricultural, open and forest habitats by juvenile Mauritius Kestrels Falco punctatus

Knowledge of tropical raptor habitat use is limited and yet a thorough understanding is vital when trying to conserve endangered species. We used a well studied, reintroduced population of the vulnerable Mauritius Kestrel Falco punctatus to investigate habitat preferences in a modified landscape. We constructed a high resolution digital habitat map and radiotracked 13 juvenile Kestrels to quantify habitat preferences. We distinguished seven habitat types in our study area and tracked Kestrels from 71 to 130 days old during which they dispersed from their natal territory and settled within a home-range after reaching independence. Mean home-range size was 0.95 km(2) characterized by a bimodal pattern of intensity around the natal site and post-independence home-range. Compositional analysis showed that home-ranges were located non-randomly with respect to habitat but there was no evidence to suggest differential use of habitats within home-ranges. Native and semi-invaded forest and grassland were consistently preferred, whereas agriculture was used significantly less than other habitats. No difference was found between the available length of edge dividing native forest and grassland within a home-range when compared to that available within a 2.35-km buffer around their nest-site, based on the maximum distance a juvenile was found to disperse. Repeating the analysis in three dimensions gave very similar results. Our results suggest that Mauritius Kestrels are not obligate forest dwellers as was once thought but can also exploit open habitats such as grassland. Kestrels may be using isolated mature trees within grassland as vantage points for hunting in the same way as they use the natural stratified forest structure. We suggest that the avoidance of agriculture is partly due to a lack of such vantage points. The conservation importance of forest degradation and agricultural encroachment is highlighted and comparisons with the habitat preferences of other tropical falcons are discussed.

Local richness and distribution of the lizard fauna in natural habitat mosaics of the Brazilian Cerrado

We investigate local lizard richness and distribution in central Brazilian Cerrado, harbouring one of the least studied herpetofaunas in the Neotropical region. Our results are based on standardized samplings at 10 localities, involving 2917 captures of 57 lizard species in 10 families. Local richness values exceeded most presented in earlier studies and varied from 13 to 28 species, with modal values between 19 and 28 species. Most of the Cerrado lizard fauna is composed of habitat-specialists with patchy distributions in the mosaic of grasslands, savannas and forests, resulting in habitat-structured lizard assemblages. Faunal overlap between open and forested habitats is limited, and forested and open areas may act as mutual barriers to lizard distribution. Habitat use is influenced by niche conservatism in deep lineages, with iguanians and gekkotans showing higher use of forested habitats, whereas autarchoglossans are richer and more abundant in open habitats. Contrary to trends observed in Cerrado birds and large mammals, lizard richness is significantly higher in open, interfluvial habitats that dominate the Cerrado landscape. Between-localities variation in lizard richness seems tied to geographical distance, landscape history and phylogenetic constraints, factors operating in other well-studied lizard faunas in open environments. Higher richness in dominant, open interfluvial habitats may be recurrent in Squamata and other small-bodied vertebrates, posing a threat to conservation as these habitats are most vulnerable to the fast, widespread and ongoing process of habitat destruction in central Brazil.

Non-random reef use by fishes at two dominant zones in a tropical, algal-dominated coastal reef

Habitat use and the processes which determine fish distribution were evaluated at the reef flat and reef crest zones of a tropical, algal-dominated reef. Our comparisons indicated significant differences in the majority of the evaluated environmental characteristics between zones. Also, significant differences in the abundances of twelve, from thirteen analyzed species, were observed within and between-sites. According to null models, non-random patterns of species co-occurrences were significant, suggesting that fish guilds in both zones were non-randomly structured. Unexpectedly, structural complexity negatively affected overall species richness, but had a major positive influence on highly site-attached species such as a damselfish. Depth and substrate composition, particularly macroalgae cover, were positive determinants for the fish assemblage structure in the studied reef, prevailing over factors such as structural complexity and live coral cover. Our results are conflicting with other studies carried out in coral-dominated reefs of the Caribbean and Pacific, therefore supporting the idea that the factors which may potentially influence reef fish composition are highly site-dependent and variable.

Time-budget and feeding behaviour of the squirrel glider (petaurus norfolcensis) in remnant linear habitat

The squirrel glider (Petaurus norfolcensis) occurs in forests and woodlands in eastern Australia. In Victoria it is now largely restricted to small, fragmented areas and is considered endangered. In this study, the time-budget, feeding behaviour and related habitat use of the squirrel glider were investigated in a linear remnant of roadside vegetation near Euroa, Victoria. Timed observations of three males and three females, fitted with radio-collars, were made in each of four seasons. Gliders were observed for a total of 53.2 h, during which they devoted 72% of time to foraging activities. Grooming accounted for 16% of observation time. Exudates associated with homopterous insects were the primary food items consumed throughout the year. Arthropods, nectar and pollen, and Acacia gum formed the remainder of the diet. The proportion of time devoted to harvesting these food items showed marked seasonal variation. The primary dependence on homopterous insect exudates in this study area contrasts with other investigations at sites of greater floristic diversity where nectar and pollen were the most important dietary resources. This highlights the need to obtain ecological information from the range of habitats occupied by a species. Large trees are a vital habitat component of remnant linear vegetation in this study area, providing gliders with critical foraging resources. Retention of such trees is essential for the longevity of glider populations.

Habitat selection by female Australian fur seals (Arctocephalus pusillus doriferus)

1. Numerous studies have determined the foraging areas of marine apex predators and investigated their relationship to oceanographic features. Most of these, however, have concentrated on surface-feeding seabirds or epipelagic-foraging marine mammals and there is little information on habitat selection in benthic divers.

2. Satellite telemetry was used during the winters of 2001-2003 to determine the foraging areas of 48 female Australian fur seals (Arctocephalus pusillus doriferus) from four breeding sites in northern Bass Strait whose colonies together represent > 80% of the total species population.

3. All individuals foraged over the shallow continental shelf of Bass Strait supporting earlier studies that suggested the species is an exclusively benthic forager. Individual females showed a high degree of foraging site-fidelity and several foraging 'hot spot' areas could be identified.

4. Analysis of habitat use indicated that individuals selected areas with depths of 60-80 m significantly more (λ = 0.216, P<0.001) than any other bathymetric class. There was also evidence for foraging areas being influenced by SST, with individuals selecting regions of 16.0-16.8 C SST (λ = 0.008, P<0.01), but not surface chlorophyll-a concentration (P> 0.05).

5. Temporal analysis of at-sea movements indicated, due to their primarily benthic foraging mode, the areas frequented by female Australian fur seals did not overlap substantially with areas targeted by commercial fisheries. An exception to this was in far eastern Bass Strait where the Otter Trawl component of the Commonwealth Trawl Sector is highly active over the continental shelf and encompasses the areas frequented by females from The Skerries colony.

Early microhabitat use by age 0 year brook charr Salvelinus fontinalis in lakes

The early habitat use of age 0 year brook charr Salvelinus fontinalis in three north temperate lakes which differ in terms of shoreline physical habitat is described. In the two lakes, which contained abundant shoreline woody debris and inundated vegetation, brook charr were observed in extremely close proximity with these habitat features, near shore and near the surface. Fish were absent from open areas away from shore unless in close proximity with fallen floating logs near the surface, extending offshore. In a third lake that had no woody debris or inundated shoreline vegetation, brook charr were observed exclusively in close proximity with the shoreline itself, and near the surface. In all three lakes, fish were most closely associated with the shoreline and with woody debris and inundated vegetation (when present) shortly after emergence, and significantly farther from shore and deeper in the water column thereafter.

Population consequences of a predator-induced habitat shift by trout in whole-lake experiments

In a replicated whole-lake experiment, we (a) tested for the existence of a flexible habitat shift in response to predator presence in age-0 rainbow trout (Oncorhynchus mykiss) at risk of cannibalism and (b) evaluated the population-level consequences of habitat shifts in terms of growth and survival over their first growing season. Daphnid food and adult trout predators were substantially more abundant in pelagic than in littoral habitats. Age-0 trout used all habitats in populations without adult trout predators, whereas age-0 trout were observed only in the less profitable littoral habitat in populations with adult trout. Consequently, mean fall mass of age-0 trout in the presence of predators was almost half that observed in populations without adult trout. Despite the shift in habitat use, age-0 trout experienced 90% mortality when adult trout predators were present, in comparison to only 36% mortality when absent. We conclude that the commonly observed habitat shifts by fish at risk of predation, observed at smaller scales, do in fact occur at the whole-system scale over long time intervals. These results suggest that fish are able to perceive risk at large spatial scales and thus take advantage of profitable (but normally risky) habitats when predators are absent, or move to less profitable refuge habitats when predators are present.

Conservation hotspots : implications of intense spatial area use by breeding male and female loggerheads at the Mediterranean’s largest rookery

The implementation of appropriate protection measures for endangered species in protected areas requires knowledge of their fine-scale habitat use. In May and June of 2006 and 2007, we used GPS loggers (some linked to the Argos system) and a conventional Argos transmitter to track male and female loggerhead turtles Caretta caretta in the vicinity of the breeding area of Laganas Bay within the National Marine Park of Zakynthos, Greece. We obtained (1) 9681 useable locations (mean: 1383 locations ind.–1; range: 519 to 2198 locations) from Tracktag GPS loggers attached to 7 females for a mean duration of 34 d (range: 17 to 52 d); (2) 1245 useable locations (mean: 311 locations ind.–1; range: 38 to 1110 locations) from 4 males fitted with Fastloc Argos tags for a mean duration of 29 d (range: 3 to 51 d) and (3) 100 locations from 1 male fitted with a conventional Argos satellite tag tracked for 128 d. GPS data indicated that before the onset of nesting, both males and females primarily used an area within 500 m of the shore along a core 9 km stretch of coastline, where existing protective legislation requires strengthening. Our observations suggest that a 76.7% female-biased operational sex ratio, measured previously from in-water surveys, may represent a realistic sex ratio estimate in the period before nesting starts. In the first month following the onset of nesting, female spatial distribution remained similar, whereas most males departed for distant areas presumably to forage. Our study provides quantitative evidence of the need to improve the management planning and conservation measures to protect sea turtles in a coastal breeding area, and new insights on male turtle migration.

Sex-biased space-use response to urbanization in an endemic urban adapter

Urbanization impacts on the composition and distribution of wildlife. The tawny frogmouth (Podargus strigoides) is an endemic, nocturnal bird species widespread throughout Australia with recent research highlighting high densities within urban environments. The aim of this study was to investigate homerange size and land-use in response to a gradient of urbanization by determining (a) the key land-use types influencing home-range size and location in the urban landscape (b) whether urbanization impacts on home-range size; and (c) whether the response to urbanization is gender specific. Twelve birds, seven male and five female were radio-tracked within a study zone located in Melbourne, Australia. We used minimum convex polygons (MCP) 95% and 50% fixed-kernel isopleths to calculate home-range size and areas of core use within each home-range. In both the landscape and core areas of their home-range, birds positioned their home-range in areas with more trees, avoiding impervious surfaces and utilizing grassed areas. Male mean kernel home-range was 17.65 ± 4.35 ha and female 6.55 ± 1.40 ha. Male home-ranges contained higher levels of impervious surfaces than females. Modelling demonstrated that as urbanization intensified the home-range size of males increased whereas female home-ranges remained static in size. This research identifies land-use selection and highlights the possibility that spatial behaviour in the species is sex-biased in response to a gradient of urbanization. © 2014 Elsevier B.V.

Avoiding competition? Site use, diet and foraging behaviours in two similarly sized geese wintering in China

Competition may occur when two species with similar feeding ecologies exploit the same limited resources in time and space. In recent years, the Eastern Tundra Bean Goose Anser fabalis serrirostris and Greater White-fronted Goose Anser albifrons frontalis have increased in wintering numbers at Shengjin Lake, China. To examine the potential for coexistence and possible avoidance strategies, we studied (1) their habitat use, (2) foraging behaviours and (3) diets of birds foraging in mixed- and single-species flocks. Both species extensively exploited sedge meadows, where they showed considerable overlap in spatial distribution and diet. The percentage feeding time and diet of both species were unaffected by the presence of the other. Greater White-fronted Geese appeared diurnal sedge meadow specialists, almost never feeding in other habitats. Eastern Tundra Bean Geese were less selective, exploiting other habitats, which they increasingly exploited at night in mid-winter. The use of alternative habitats and night feeding may have avoided interspecific competition. While the specialised feeding ecology of Greater White-fronted Geese may make them particularly vulnerable to loss of sedge meadow habitat, Eastern Tundra Bean Geese may be able to adjust because of their use of alternative habitats and a less restricted diet.

Combined use of GPS and accelerometry reveals fine scale three-dimensional foraging behaviour in the short-tailed shearwater

Determining the foraging behaviour of free-ranging marine animals is fundamental for assessing their habitat use and how they may respond to changes in the environment. However, despite recent advances in bio-logging technology, collecting information on both at-sea movement patterns and activity budgets still remains difficult in small pelagic seabird species due to the constraints of instrument size. The short-tailed shearwater, the most abundant seabird species in Australia (ca 23 million individuals), is a highly pelagic procellariiform. Despite its ecological importance to the region, almost nothing is known about its at-sea behaviour, in particular, its foraging activity. Using a combination of GPS and tri-axial accelerometer data-loggers, the fine scale three-dimensional foraging behaviour of 10 breeding individuals from two colonies was investigated. Five at-sea behaviours were identified: (1) resting on water, (2) flapping flight, (3) gliding flight, (4) foraging (i.e., surface foraging and diving events), and (5) taking-off. There were substantial intra- and inter- individual variations in activity patterns, with individuals spending on average 45.8% (range: 17.1-70.0%) of time at sea resting on water and 18.2% (range: 2.3-49.6%) foraging. Individuals made 76.4 ± 65.3 dives (range: 8-237) per foraging trip (mean duration 9.0 ± 1.9 s), with dives also recorded during night-time. With the continued miniaturisation of recording devices, the use of combined data-loggers could provide us with further insights into the foraging behaviour of small procellariiforms, helping to better understand interactions with their prey.

Uso de habitat e comportamento do boto-cinza sotalia guianensis em uma zona estuarina do estado de Sergipe, nordeste do Brasil a biotecnologia vegetal como alternativa para a cotonicu

To clarify the functional mechanisms of habitat use is necessary to analyze it in conjunction with the conduct performed by animals. The occurrence, distribution and use of space are characteristic of a species resulting from habitat selection that is in search of conditions favorable to its survival. One can relate the physical and biological factors of the environment with the ecological characteristics of the species, since these factors act by regulating the ecological success of organisms, and from there you can get important information about the habitat use and behavior of individuals. This study aimed to characterize the use of habitat and diurnal activity expressed by the Guiana dolphin, Sotalia guianensis in an estuarine area of Sergipe state, Brazil, analyzing the influence of tide and time days on the occurrence of animals and behavior s state, and group s size and composition in this cetacean species. From March 2009 to February 2010, focal groups observations of dolphins were made from fixed - point and records snapshots of data taken every 5 min. in the interval from 6 a.m to 6 p.m, in alternating shifts. The results showed that the constant presence of animals in the area of the Sergipe River estuary indicates that this is an important area of occurrence of S. guianensis, which use the region mainly in the morning, at low tide and as a feeding. As in other regions of northeastern Brazil, small groups formed 2-12 individuals were most common, with adults and immatures. The high frequency of immature animals may indicate that this area of the estuary is used as brood area and parental care of pups and young animals, since the immature animals were very associated with adults and monitoring the activities of foraging / feeding may be related to a form of learning or training of such behavior