Functions of restored wetlands for juvenile salmon in an industrialized estuary

The Duwamish estuary is an industrialized waterway located in Seattle, WA, USA. Despite a history of habitat loss, naturally produced juvenile Chinook salmon use the estuary. In addition to experiencing degraded habitat in the estuary, wild salmon growth may be affected by competition with more than three million hatchery fish released yearly into the river. Restoring habitat to benefit salmon in the Duwamish River is a priority for trustees of public resources, and a number of wetland restoration sites have been created there. We tested the function of restored sites in the Duwamish estuary for juvenile Chinook salmon by comparing fish densities from enclosure nets or beach seines at three paired restored/un-restored sites and by applying environmental and diet data to a bioenergetics model. We also examined temporal and diet overlap of wild juvenile Chinook salmon with other salmon species and with hatchery-reared Chinook salmon using non-metric multidimensional scaling (NMDS). At a brackish upstream site with a relatively large opening to the river, we found higher densities of juvenile Chinook salmon at the restored site. NMDS results indicated that juvenile Chinook salmon fed on different taxa at the restored sites than at the reference sites. However, modeled growth was similar at restored and reference sites. Co-occurring juvenile chum and Chinook salmon fed differently, with chum eating smaller prey, and Chinook salmon eating larger prey. Co-occurring hatchery and wild juvenile Chinook salmon had similar diets, indicating that they may compete for prey. However, modeled growth was positive and did not differ between hatchery and wild fish, suggesting that food was not limiting. Bioenergetics models indicated that overall juvenile Chinook salmon growth potential at the brackish water site was consistently higher than at more saline sites. Our results suggest that restoration sites in the Duwamish estuary that have larger access openings and are located in brackish water may have increased function over other configurations.     

Functions of fights in territory establishment

Fights are often observed when prospective territory owners settle in patches of vacant habitat, but the function of these fights in space acquisition is obscure. This study tests two hypotheses about the effect of fights on subsequent space use patterns: first, that settlers win space by winning fights and, second, that fights encourage the establishment of mutually exclusive home ranges between opponents (i.e., "fights make neighbors"). The behavior of juvenile Anolts aeneus lizards was recorded as they established territories in patches of habitat in the field. In support of the fights-make-neighbors hypothesis, opponents whose last aggressive interaction was a fight were six times more likely to have mutually exclusive home ranges at the end of the settlement period than were otherwise equivalent dyads whose last encounter was a chase. Contra the hypothesis that settlers win space by winning fights, most last fights ended in a draw, and there was no discernable relationship between the outcome of last fights and the subsequent space use of the contestants. These and previous analyses of settlement behavior in this species suggest that fights during the settlement period encourage the formation of symmetrical social and spatial relationships between neighboring settlers.     

Is Atlantic salmon production limited by number of territories?

Thirty Atlantic salmon Salmo salar parr (mean 135 mm total length, L _T) in the River Alta, Norway, were radio‐tagged and tracked during a 11–13 day period. The parr stayed within defined home ranges with a 95% probability of localization within an average area of 1286 m²(241–3484 m²). On average, each parr had overlapping home ranges with 7·7 other parr, and the overlap between pairs of fish covered on average 24% of their home range areas. Mean length of the river stretch used was 90 m (22–383 m). On average, during 38%(16–77%) of the tracking surveys, the fish had moved >10 m since the previous survey. Mean total distance moved during the whole study was 402 m (208–862 m). The Atlantic salmon were most often recorded in riffles, but 27% of the parr alternated between riffles and pools. The extensive movements, flexible habitat utilization and relatively large home ranges, together with the fact that all the parr had home ranges partly overlapping with other radio‐tagged parr, indicate a flexible and variable behaviour and, thereby, a more complex social structure than a rigid defence of a fixed territory. Thus, Atlantic salmon production seems not to be limited by the highest potential number of territories for large parr in a given area.     

利用卫星追踪颈圈对圈养野生双峰驼野化放归的监测

2012-2014年,通过对甘肃敦煌西湖国家级自然保护区野化放归的两峰野生双峰驼（Camelus ferus）佩带卫星追踪颈圈进行跟踪监测,利用最小凸多边形法和内核法开展了放归生境中野骆驼的活动范围和空间利用研究。研究期间,分别进行了22个月(ID:108444)和9个月(ID:108445)的跟踪监测,获得了3403个(ID:108444) 和1573个(ID:108445)定位成功的GPS位点。野骆驼放归后的前两个月仍存在一定的对圈养环境的依赖,两个月后野骆驼的活动范围开始向外扩展,直至四个月后,基本扩展至整个放养的围栏,活动范围分别从9.5109 km²增加到19.3694 km2 (ID:108444),8.8943 km² 增加到19.4192 km² (ID:108445)。整个监测期间,95% Kernel活动范围分别为7.7181km² (ID:108444) 和 3.0321 km² (ID:108445)。从整个监测期间(ID:108444)的50% Kernel活动范围（0.2811 km²）来看,野骆驼整个放归期间仍然比较依赖原先的圈养环境;野骆驼存在对胡杨疏林的偏好;同时,放归的野骆驼仍然保持了对人的亲近行为。从2013年整年来看,放归野骆驼实际生境利用,春、秋两季范围大,夏、冬两季范围较小。放归的野骆驼不同季节对主要生境的利用也有所不同,最为明显的是夏季,野骆驼活动范围集中在荒漠地区,避开植被多的区域以避免蚊虫叮咬。本研究进一步了解了野骆驼的行为习性及其适应环境的行为对策,为野骆驼圈养种群的科学管理和进一步野化放归提供了理论依据。     

Spacing behaviour and habitat use of rock ptarmigan (Lagopus mutus) at low density in the Italian Alps

Studies of rock ptarmigan Lagopus mutus in northern latitudes have shown that, in the breeding season, the majority of cocks pair monogamously and defend small territories, whilst in most populations, a small proportion of cocks are polygynous or remain unmated. Little is known, however, on spacing behaviour and habitat use of alpine rock ptarmigan populations occurring at low densities at the southern edge of the species’ range. From 1995 to 1997, we trapped, radio-tracked and observed birds in the Central Italian Alps (elevation 2,000–3,000 m) in order to investigate spacing behaviour and habitat use in alpine landscapes where habitats offering rich food and cover are patchy. Both sexes were selective in their habitat use, and cocks did not establish territories on bare ground, artificial or nutrient rich grasslands or bogs. In the breeding season, cocks had larger home ranges than hens (cocks 99 ± 57 ha, hens 50 ± 25 ha) that overlapped with the ranges of neighbouring cocks and hens. Cocks were monogamous and defended relatively large territories (core areas of home ranges: cocks 37 ± 26 ha, hens 24 ± 12 ha), which corresponded with low spring densities (0.47–2.29 cocks km⁻² and 0.35–1.60 pairs km⁻²). Territory size of individual cocks was negatively correlated with the amount of high quality habitat in the core-area. Our results suggest increased home ranges and large breeding territories in low density alpine rock ptarmigan populations, compared to populations occurring at higher densities in the central and northern alps, and on subarctic and arctic grounds at northern latitudes, confirming the predictions of models on food-based territoriality.     

Home range of juvenile Atlantic salmon, Salmo salar, and brown trout, Salmo trutta, in a Norwegian stream

SUMMARY. 1. The sizes of home ranges of juvenile Atlantic salmon (age 1 +) and brown trout (age 2+ to 9+) in a Norwegian coastal stream were estimated by local movements of batch-marked fish from 12.5 and 25 m long sections. Only recoveries made in the release section and in up-and downstream neighbouring sections were considered.
2. There was no significant difference in the average percentage of recaptures of salmon and trout between 12.5 and 25 m sections; a stream area of about 40–50 m² defines the size of home range for stocks of both species.
3. The fraction of brown trout recaptured in release sections increased with increasing fish densities, indicating a smaller home range under these conditions.     

A division between foraging range and territory related to food distribution in the red fox

Spatial organization of the red fox (Vulpes vulpes schrencki) was investigated on the basis of seasonal food distribution in the Shiretoko National Park, Hokkaido from 1992 to 1994. Four periods were recorded pertaining to the distribution of 2 kinds of food resources: human food and spawning salmonid carcasses. The home range utilizations of radio-collared foxes were compared for the periods. In the periods when food was not spatially concentrated, resident foxes were territorial, showing exclusive distribution of home ranges between families, defense against intruding foxes at the edge of home ranges, and site specific dominance over intruding foxes. In contrast, during periods when food distribution was concentrated, home ranges overlapped. In the latter periods, foxes made round trips of up to 8 km from their territories to the localized concentration of food, the distance that foxes can travel within a day. This suggests that red foxes in this area have unique foraging ranges that include some seasonally available food outside their territories, and that these ranges depend on fluctuating food distribution caused by humans.     

Effect of density on competition between wild and hatchery‐reared Atlantic salmon for shelter in winter

The effect of varying the density of hatchery‐reared Atlantic salmon Salmo salar on the ability of single wild fish to occupy a shelter is assessed. Although there was strong density‐dependence on sheltering overall, the ability of wild Atlantic salmon parr to occupy a shelter was not affected by the presence of hatchery‐reared fish even when outnumbered by four to one. These findings illustrate a competitive asymmetry for shelter in favour of the wild fish at the densities tested.     

Multiple central-place territories in wild young-of-the-year Atlantic salmon Salmo salar

1. The space use of central-place foragers, animals that forage from and return to a single central place such as a nest, burrow or sleeping site, is well documented. Limited data, however, exist for multiple central-place foragers that alternate among several central places. 2. The conventional view of stream-dwelling salmonids suggests that they conform to the central-place territorial model (CPTM) by (i) attacking prey and intruders from one primary foraging station, and defending (ii) small (iii) exclusive areas that (iv) increase with body size. 3. Recent studies suggest greater variability in salmonid space-use than would be expected by the CPTM, but tend to focus on the time allocated towards different activities rather than their distribution in space, especially for young-of-the-year (YOY) fish that are hard to tag and monitor in the wild. 4. In this study, the validity of CPTM was tested by mapping the daily space use of 50 YOY Atlantic salmon in a natural stream via repeated observations of tagged fish in diverse habitats, and by comparing these to earlier estimates of territory use in YOY salmonids. 5. The 50 YOY Atlantic salmon were multiple central-place foragers. All fish visited more than one foraging station (median = 12.5 stations), visited most stations (68.5%) repeatedly, showed limited fidelity to a particular station and typically attacked prey only while holding a position at a station. 6. The multiple central-place territories of the 50 fish were large (mean = 0.932 m(2)) compared to earlier territory size estimates (mean = 0.107 m(2)) for salmonids of similar size and, surprisingly, did not increase with body size. Focal fish attacked intruders from similar distances as reported earlier for much smaller territories, suggesting that large territories are less exclusively defended at any given time. 7. Overall, this study provides a new view on foraging and territoriality in stream salmonids, and on the small but diverse literature on multiple central-place foragers. Further studies, however, are needed to clarify the evolutionary benefits and population consequences of multiple central-place space-use in mobile animals.     

Structure of arctic fox (Alopex lagopus beringensis) colonies in the northern extremity of Bering Island

Data on the spatial structure of an Arctic fox (Alopex lagopus beringensis) colony were obtained in July-August 1995, using walk counts and observations near living dens around the Northern rookery of the northern fur seals located on Bering Island (Commander Islands). The home ranges of 31 Arctic fox families (61 adults and 145 pups inhabiting 66 dens) were found over 27 km of the coastline. Sixty individuals (3 adults and 57 pups) were marked by color ear-tags. Among adult foxes, 24 (39.3%) were recognized as females and 12 (19.7%) as males; the sex of 25 (41.0%) foxes was not recognized. Among 57 marked cubs, 26 (45.6%) were females and 31 (54.4%) were males. The best studied families (13) had 3–11 pups (6.7 ± 0.7, on average). The survival of cubs at an age younger than 2.0–2.5 months was 82.5%; 30.8% of the families consisted of more than two adults. The distribution of the Arctic fox dens and home ranges along the coastline has been studied; specific features of the location of dens have been described. In the studied area, Arctic foxes have been foraging on birds (67.6% of dens with food remains), northern fur seals (40.5), other marine mammals (13.5), Pacific salmon (29.7), and reindeer (2.7%), as well as on amphipods and voles. Rich constant food sources (rookeries, marine bird colonies, and spawning places of the blueback salmon) were found in 7 home ranges of the Arctic fox; 6 home ranges included temporary food sources (spawning streams of the humpback salmon); and 18 home ranges were poor in food resources. Arctic foxes whose home ranges lie within 6–7 km around a “food patch” used the concentrated food resources together. Food resources are supposed to become important only after the raised pups turn to self-feeding. Differences in the use of space, foraging and breeding of the two Arctic fox subspecies (A. l. beringensis and A. l. semenovi), and arrangement of colonies around the northern fur seal rookeries are discussed.     

Experimental analysis of resource sharing between herbivorous damselfish and blennies on the Great Barrier Reef

Competition theory suggests that species with very similar resource requirements should not be able to coexist when resources are limiting. However, on coral reefs, territorial herbivorous fishes which use apparently very similar resources often coexist without competitive exclusion. This study investigates patterns of resource use by damselfish Pomacentrus flavicauda Whitley and blennies, primarily Salarias fasciatus Bloch, living in rubble habitats on the Great Barrier Reef. These species feed mainly on turf algae and have overlapping territories and home ranges. I ask two questions:

• 1.(1) is there any evidence of resource partitioning between these species; and
• 2.(2) do they compete for food or space? It is highly unlikely that damselfish and blenny species partition food resources by eating different species of algae, since species are intermixed at a very small scale in the algal turf. Instead, differences in food use were looked for by counting the numbers of bites fish of each species took from different parts of the rubble habitat.

Little difference in food use was found between Pomacentrus flavicauda and Salarias fasciatus except that the former fed on plankton to some extent whilst the latter did not. A manipulation experiment was performed to assess whether blennies inhabiting damselfish territories competed with damselfish for algae. Damselfish territories were used as experimental units and two manipulations performed:

• 1.(1) S. fasciatus removal, and
• 2.(2)Pomacentrus flavicauda removal.

There were four replicates of each with four undisturbed controls. Territory sizes, feeding rates and attack rates on other fishes of P. flavicauda were measured before and after blenny removal. Blenny density and biomass were measured before and after P. flavicauda removal. None of these measures provided evidence of exploitation competition between these species or of changes in levels of interference competition by damselfish after blenny removal. Blenny densities and biomass did not change significantly after damselfish removal. Damselfish appear to tolerate blennies within their territories because they cannot economically exclude them. However, the intermittent availability of an alternative source of algae outside damselfish and blenny territories and home ranges may mean that algae are not normally a limiting resource.     

Home ranges of brown bears on the Kamchatka peninsula and Sakhalin Island

Territorial activity was studied using satellite tracking of four brown bears (Ursus arctos) in Kamchatka in 2005–2006 and three brown bears on Sakhalin in 2011–2012. The size of annual home ranges was 6.09–27.58 km² for females and 153.12 km² for males. The size of the nuclear zone of the annual home ranges did not exceed 1.68 km². Seasonal home ranges were largest in August-September and smallest in May. The home ranges of two females in Kamchatka were significantly overlapped, the lesser degree of overlap was noted for two females on Sakhalin. The nature of the use of the study area by bears, essentially depends on the seasonal distribution of food, in particular salmon.     

Do Forest Composition and Fruit Availability Predict Demographic Differences Among Groups of Territorial Owl Monkeys (Aotus azarai)?

Small-scale ecological variables, such as forest structure and resource availability, may affect primate groups at the scale of group home ranges, thereby influencing group demography and life-history traits. We evaluated the complete territories of 4 groups of owl monkeys (Aotus azarai), measuring and identifying all trees and lianas with a diameter at breast height ≥10 cm (n = 7485). We aimed to determine all food sources available to each of those groups and to relate food availability to group demographics. For analyses, we considered the core areas of the home range separately from the 80% home range. Our results showed that groups occupy territories that differ in size, species evenness, stem density, and food species’ stem abundances. The territories differed in the availability of fruits, flowers, and leaves, and most fruit sources were unevenly distributed in space. Differences among territories were more pronounced for the whole range than they were for the core areas. Despite marked differences among territories in structure and food availability, the number of births and age at natal dispersal were quite similar, but 1 group had a consistently lower group size. Our results suggest that owl monkey groups occupy territories of different structure and composition and food availability, yet ones that contain similar quantities of, mostly, dry season fruit sources. We propose that groups inhabit these territories to overcome food shortages safely during limiting periods, specifically the dry season, in this markedly seasonal forest. The occupancy and defense of territories with strict boundaries may therefore be associated with food resources available during limiting seasons that may be the ones influencing life history patterns and demographics.     

Intra- and Interspecific Competition in Hatchery Landlocked Salmon and Brown Trout in Semi-Natural Streams

I studied inter- and intraspecific competition in two hatchery stocks: landlocked salmon with long-hatchery background and a heterogenic brown trout stock. These species are potential competitors in the natural environment when landlocked salmon is being restored to wild by stocking hatchery juveniles. Behavioural responses were studied in four indoor laboratory flumes (400 cm long and 37 cm wide) and habitat use in six semi-natural outdoor streams (26 m long and 1.5 m long). Video recordings were used to monitor fish behaviour and electrofishing for fish positioning in the outdoor channels. The study design included five treatments: two densities of brown trout and salmon in solitary and both species together. The results of the study demonstrated that juvenile brown trout changed their behaviour in laboratory streams in response to presence of the landlocked salmon and the density of the conspecifics also tended to alter the habitat use by brown trout in semi-natural streams. Landlocked salmon juveniles showed no response to treatments. I conclude that possible poor adaptive ability to conditions outside hatchery by the hatchery salmon together and more competitive brown trout stocks may limit the success of management action in restoring landlocked salmon back to their natural streams of stocking.     

Prior residence, territory quality and life-history strategies in juvenile Atlantic salmon (Salmo salar L.)

Three groups of juvenile salmon were introduced sequentially into an artificial stream to investigate the effects of prior residence on behaviour and territory choice. Almost half of the first group obtained and defended distinct territories, the other half being constrained to an area approximately the size of one large territory. All of the fish in the subsequent groups, bar one, were also constrained to the same site. Since the fish were of similar size, prior residence alone seemed to influence which individuals obtained territories. However, within the first group, the fish that obtained territories were larger and more aggressive. The territorial fish did not appear to choose the most profitable territories, although they had the greatest opportunity to do so. Since juvenile salmon emerge from their gravel nests fairly synchronously, a time constraint on site sampling is hypothesised: there may be a risk in taking time to sample sites, since these same sites may become occupied with conspecifics. However, fish with territories fed at faster rates than non-territorial fish, possibly because of reduced competition for prey items. Consequently, fish from the first group (containing most of the territorial fish) grew faster than the other two groups. Moreover, most of the territory holders, but only one of the non-territorial fish, reached the threshold size that increases their probability of smolting the following year. This suggests that ability to obtain a defensible territory, primarily through prior residence, influences the age at which juvenile salmon can migrate to sea.     

Population fluctuations in relation to seasonal habitat preferences of the Swainson's spurfowl, Pternistis swainsonii

Counts on Swainson's spurfowl Pternistis swainsonii were made during 1998–1999 within an intensive, fine‐grained, agricultural landscape to estimate population parameters, seasonal dispersion and habitat preferences. Radio‐transmitters were fitted to four birds to note habitat use and home ranges within the Summer breeding season. During Winter, population densities peaked, and birds exploited agricultural crops extensively. At the onset of Spring, densities dropped as birds paired to establish non‐overlapping breeding territories over a number of habitats with apparently sufficient cover and ‘natural’ food. Expanding grazed grassland appears to be the greatest threat to Swainson's spurfowl due to a lack of cover and food. The matrix of habitats within the landscape plays important roles in the success of this opportunistic spurfowl. Agricultural crops in the Winter sustain the population until the following Summer when natural savanna and ungrazed grasslands provide complementary foraging, nesting and roosting sites.     

Territoriality of Feral Pigs in a Highly Persecuted Population on Fort Benning,Georgia

ABSTRACT We examined home range behavior of female feral pigs (Sus scrofa) in a heavily hunted population on Fort Benning Military Reservation in west-central Georgia, USA. We used Global Positioning System location data from 24 individuals representing 18 sounders (i.e., F social groups) combined with mark-recapture and camera-trap data to evaluate evidence of territorial behavior at the individual and sounder levels. Through a manipulative experiment, we examined evidence for an inverse relationship between population density and home range size that would be expected for territorial animals. Pigs from the same sounder had extensive home range overlap and did not have exclusive core areas. Sounders had nearly exclusive home ranges and had completely exclusive core areas, suggesting that female feral pigs on Fort Benning were territorial at the sounder level but not at the individual level. Lethal removal maintained stable densities of pigs in our treatment area, whereas density increased in our control area; territory size in the 2 areas was weakly and inversely related to density of pigs. Territorial behavior in feral pigs could influence population density by limiting access to reproductive space. Removal strategies that 1) match distribution of removal efforts to distribution of territories, 2) remove entire sounders instead of individuals, and 3) focus efforts where high-quality food resources strongly influence territorial behaviors may be best for long-term control of feral pigs.     

Home range and territory of the Sardinian Warbler Sylvia melanocephala in Mediterranean shrubland

Capsule Singing territories were well separated.

Aims To examine the spatial distribution of Sardinian Warbler males during the breeding period in Mediterranean shrubland and, specifically, their territories, home ranges and spatial overlaps.

Methods We studied a 12-ha plot of Mediterranean shrubland in the 1997 to 1999 breeding seasons. Sardinian Warblers were captured using mist-nets, colour-ringed and their territories mapped. In 1999, seven breeding males were radiotracked in order to map home ranges.

Results The Sardinian Warbler had an average of 7.3 breeding pairs/10 ha in the study plot. The mean territory size was 8779 m² and the mean home range was 22 321 m². A positive relationship was found between the area of the home range and singing territory. Home ranges of males born in 1998 were about half the size of those of the oldest males. Paired males who moved with a female had smaller home ranges than those that were either unpaired or whose mate was incubating. The degree of home range overlap was high with some overlap between neighbouring territories. The estimate of home range area increased by 10% when the information generated by a mapping method was added and the estimated territory area increased by 31% when data generated by radiotracking were added. Transmitters remained attached to birds for an average of 9.63 ± 3.46 days (mean ± se).

Conclusions Singing territories were segregated to a considerable degree. In contrast, the wide overlaps among home ranges was best explained by the presence of food resources that the males exploit at the same time and also by the search for extra-pair copulation in nearby territories. We consider radiotracking in this species to be feasible and valid, with no evidence of negative effects on activity levels, weight or mortality.     

Do parasites affect the behavior of the Hawaiian white-spotted toby, Canthigaster jactator (Pisces)?

This study observed differences in behavior associated with parasites in the fish Canthigaster jactator. These fish were observed both within Kaneohe Bay, Oahu, Hawaii, and just outside the bay. Normal (unparasitized) fish behaved similarly to their congeners. Behavior varied by size class and presumed sex. Larger fish (males) patrolled territories and courted medium-sized fish (females), which freely crossed male territories. Smaller fish appeared to be immature and remained in limited home ranges on the edge of male territories. All fish parasitized with a philometrid nematode acted most like immature ”normal” fish, with limited home ranges and few social interactions. However, parasitized fish ate at twice the rate of unparasitized fish. All fish collected from the bay contained some parasites, and none were sexually mature, whereas no parasites were found in fish from outside the bay. These data suggest that parasites affect the behavior of C. jactator. Moreover, parasites may limit the sexual maturation of their hosts.     

Diel activity and home range size in relation to food supply in a drift-feeding stream fish

Individuals within a species often compete for resources inboth space and time. In dominance hierarchies individuals withthe greatest competitive ability will occupy prime locationsduring optimal periods. We compared spatial and temporal useof habitat, aggression, and feeding success among giant kokopu(Galaxias argenteus) in dominance hierarchies under normal andreduced food supply. Under normal food supply conditions dominantfish were predominantly nocturnal and maintained large homeranges at night. Conversely, subdominant fish were diurnal andoccupied large home ranges by day but were generally not observedat night. When the food supply was limited, the utilizationof pools was determined by social rank. Dominant fish from eachpool increased diurnal activity, home range size, aggressiveness,and the capture of food items offered by day while simultaneouslyreducing the spatial and temporal activity and habitat use ofsubdominant fish. These results indicate that behavioral changesin large dominant fish influence and reduce the amount of resourcesavailable to subdominant fish.