Fence effects on the behavioural responses of South American fur seals to tourist approaches

Animals that breed in coastal colonies, such as pinnipeds, usually attract tourism, which can negatively affect their resting and breeding behaviour if not managed properly. One strategy to reduce human disturbance is to set up fences, but little is known about their local effectiveness. Our purpose was to assess the behavioural responses of South American fur seals (Arctocephaalus australis) towards tourist approaches before and after the implementation of fences in Cabo Polonio colony (Uruguay). We found that human disturbance levels were similar between years and that the presence of a fence reduced (1) overall fur seal responses to tourists by 60%, (2) the most intense behavioural responses (threat, attack, leaving the colony) by more than half, (3) the responses to large tourist groups (>2 people), which were the most disturbing, (4) the responses to closer (<10 m) tourist approaches, and (5) the responses involving more intrusive tourist behaviours (running, shouting, hand waving). Overall, we showed that after the erection of the fence not only human–wildlife interactions were reduced but also the most stressful fur seal behavioural responses. Although further studies are necessary, our results suggest that the implementation of fences can be a simple and affordable means of minimising human disturbance effects on pinnipeds at local levels (e.g., within colonies), particularly if combined with other strategies (e.g., changes in tourist attitudes).     

Feeding ecology of Antarctic fur seals at Cape Shirreff,South Shetlands,Antarctica

This study examined the diet of Antarctic fur seals, Arctocephalus gazella, from an active breeding colony at Cape Shirreff (62°28S, 60°48W), Livingston Island, South Shetland Archipelago, Antarctica. It analysed faecal samples from five consecutive years (1997–2001) and length distribution of krill taken by trawl nets in the vicinity of Livingston Island. Antarctic krill, Euphausia superba, was the most frequent prey item, followed by several myctophid species (Gymnoscopelus nicholsi, Electrona antarctica and Electrona carlsbergi), squid and penguin remains. From 1998 to 2001, a modal progression in krill size was evident, suggesting that A. gazella was depending on a strong krill cohort, at least over the study period. Analysis of size distribution and size selectivity of krill preyed upon by fur seals suggests a preference for larger krill (>34 mm), despite the broader size range of preys items available.     

Olfactory discrimination ability of South African fur seals (Arctocephalus pusillus) for enantiomers

Using a food-rewarded two-choice instrumental conditioning paradigm we assessed the ability of South African fur seals, Arctocephalus pusillus, to discriminate between 12 enantiomeric odor pairs. The results demonstrate that the fur seals as a group were able to discriminate between the optical isomers of carvone, dihydrocarvone, dihydrocarveol, menthol, limonene oxide, α-pinene, fenchone (all p < 0.01), and β-citronellol (p < 0.05), whereas they failed to distinguish between the (+)- and (?)-forms of limonene, isopulegol, rose oxide, and camphor (all p > 0.05). An analysis of odor structure–activity relationships suggests that a combination of molecular structural properties rather than a single molecular feature may be responsible for the discriminability of enantiomeric odor pairs. A comparison between the discrimination performance of the fur seals and that of other species tested previously on the same set of enantiomers (or subsets thereof) suggests that the olfactory discrimination capabilities of this marine mammal are surprisingly well developed and not generally inferior to that of terrestrial mammals such as human subjects and non-human primates. Further, comparisons suggest that neither the relative nor the absolute size of the olfactory bulbs appear to be reliable predictors of between-species differences in olfactory discrimination capabilities. Taken together, the results of the present study support the notion that the sense of smell may play an important and hitherto underestimated role in regulating the behavior of fur seals.     

Behavioural responses to food addition by hedgehogs

We conducted a field experiment at a 4-ha sports ground in Oxford between May and August 1992 to analyse the role of learning and social organization m the short-term responses of hedgehogs Erinaceus europaeus to manipulations of food availability On six nights we uniformly distnbuted 36 'prey' (cat food chunks) twice a night in an 70 × 70 m area (the 'patch') Prey were placed at sites marked with small flags In a subsequent experiment lasting five nights, non-marked and randomly distributed prey were provided We regularly mapped the position of individuals, before, during and after both food supplementation treatments Hedgehogs showed a stable pattern of spatial utilisation of the habitat during the non-hibernation months prior to experimental perturbation Addition of food to parts of the habitat significantly and rapidly changed these patterns a) Hedgehog density increased in food supplemented pans of the habitat b) Hedgehogs learned to associate visual cues with the presence of food c) Hedgehogs learned the spatial location of patches d) Hedgehogs probably engaged in 'area restricted' searching Hedgehogs had overlapping home ranges but showed a uniform distribution within patches and avoided conspecifics at distance < 30 m The number of different individuals visiting the area decreased throughout the experiment Food addition did not significantly change the mean density of hedgehogs, perhaps because social interactions placed an upper limit on density in the areas with supplementary food     

The behavioural response of Australian fur seals to motor boat noise

Australian fur seals breed on thirteen islands located in the Bass Strait, Australia. Land access to these islands is restricted, minimising human presence but boat access is still permissible with limitations on approach distances. Thirty-two controlled noise exposure experiments were conducted on breeding Australian fur seals to determine their behavioural response to controlled in-air motor boat noise on Kanowna Island (39°10'S, 146°18'E). Our results show there were significant differences in the seals' behaviour at low (64-70 dB) versus high (75-85 dB) sound levels, with seals orientating themselves towards or physically moving away from the louder boat noise at three different sound levels. Furthermore, seals responded more aggressively with one another and were more alert when they heard louder boat noise. Australian fur seals demonstrated plasticity in their vocal responses to boat noise with calls being significantly different between the various sound intensities and barks tending to get faster as the boat noise got louder. These results suggest that Australian fur seals on Kanowna Island show behavioural disturbance to high level boat noise. Consequently, it is recommended that an appropriate level of received boat sound emissions at breeding fur seal colonies be below 74 dB and that these findings be taken into account when evaluating appropriate approach distances and speed limits for boats.     

How mothers find their pups in a colony of Antarctic fur seals

In Antarctic fur seals, Arctocephalus gazella, mothers must identify their own young among hundreds or even thousands of pups, if they are to invest in their own offspring and avoid misdirecting their parental care. When returning to their breeding colony from a foraging trip of several days at sea, mothers have to find and identify their young before suckling can occur. There appears to be little confusion about which pup belongs to a mother, and adoption is absent or rare. Using behavioral observations, we investigated the means by which female Antarctic fur seals identified their pups in a breeding colony of about 750 mother-pup pairs on Kerguelen Island. We evaluated the importance of vision, scent communication, vocalizations, and rendezvous locations as possible explanations of how mothers find their pups. Every pup that a mother examined, whether her own or not, exchanged naso-nasal inspection with her, suggesting a strong role for olfactory communication in individual recognition. Both mothers and pups called to each other, and mothers that searched for pups over a longer period gave more calls and encountered more pups. Thus, vocalizations may have been used to attract pups that might be offspring. Nursing usually occurred in the same place from the end of one maternal visit to the colony and the arrival at the beginning of the next visit, suggesting that nursing locations may serve as a meeting place, or rendezvous, for mothers and pups. These results suggest that finding pups is a two-stage process for females, in which pups for sampling are attracted by calls or examined at the previous nursing location, and then individual identification is made by olfactory cues.     

Multiple origins of vagrant Subantarctic fur seals: a long journey to the Brazilian coast detected by molecular markers

In this study, we present the first data about putative source populations of the vagrant Subantarctic fur seal, Arctocephalus tropicalis, found on the Brazilian coast, through the comparison of their mitochondrial DNA control sequences to exclusive haplotypes from the main breeding colonies of the species. The results indicated that, despite the majority of the vagrant individuals are from Gough Island (the closest breeding site to the Brazilian coast), they also come from other reproductive colonies, such as Crozet Island, a distance around 16,500 km from the Brazilian coast. Furthermore, the molecular data identified three possible management units: (1) Gough, (2) Amsterdam, and (3) Marion, Macquarie and Crozet. This significant genetic subdivision must be taken into account in any future management plan for the species conservation, including rehabilitation and even reintroduction of vagrant fur seals. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Behavioural responses to video playbacks by zebra finch males

A major problem for communication research is to provide standardized stimuli and to disentangle the relative contribution of different sensory channels to the compound signal and its effectiveness. Video techniques have frequently been used for this purpose. Fifty Hertz cathode ray tube (CRT) screens cannot be used for birds because their flicker frequency is lower than the time resolution of at least songbirds. Thin film transistor (TFT) screens have successfully been used to present video clips of behaving conspecifics. We show here that they are indeed transmitting video images in a way that enables zebra finches to react appropriately to live video images of conspecifics and that the test birds are able to detect small differences in the behaviour of the stimulus animals. Adding acoustic information strongly enhanced the reaction to the video clips.     

Long-term variability in the abundance of Antarctic fur seals Arctocephalus gazella at Signy Island, South Orkneys

The number of Antarctic fur seals Arctocephalus gazella hauled out at Signy Island in the South Orkneys was monitored annually between 1977 and 2008. Over the study period seal abundance showed a tenfold increase, from a minimum of 1,643 seals in 1978 to a maximum of 21,303 in 1994. The majority of individuals observed were young adult males, likely to be migrants from South Georgia, with small numbers of female seals and only 65 pups recorded during the survey period. Variability in counts showed a similar pattern to Laurie Island, also in the South Orkneys archipelago, suggesting a similar annual immigration of seals to these two islands. The date of first seal arrival was correlated with the date of fast-ice breakout at Factory Cove, Signy Island, and years in which break out was exceptionally late (>21 December) corresponded with years of reduced seal abundance. While the presence of fast-ice during the early breeding season may currently inhibit the establishment of a major breeding population of fur seals at Signy Island, it is important that routine monitoring should continue, particularly in the light of current patterns of climate warming in the Antarctic.     

Behavioural responses of invasive American mink Neovison vison to an eradication campaign, revealed by stable isotope analysis

1.  The detrimental impacts of invasive, non-native species on islands are widely acknowledged and it is often best to act rapidly against such species, even where uncertainty exists over the best way to proceed. If management actions are evaluated and refined, using information learnt from the biology of culled animals, this uncertainty can be gradually reduced, increasing the likelihood of a successful outcome.
2.  American mink Neovison vison carcasses were collected as part of an eradication campaign on several islands of the Outer Hebrides, Scotland, and stable isotope analysis was used to describe ecological variation in this invasive non-native predator.
3.  Isotope profiles from individual mink whiskers demonstrated how behaviour at a population level changed markedly over time. As the eradication campaign progressed, mink increased their reliance on marine food sources and focused their activity on the coastline. Stable isotope analyses also demonstrated sex-related changes in foraging and ranging behaviour in relation to food resource availability on the two main island complexes.
4.   Synthesis and applications. Our findings contribute to the refinement of a campaign to extend the successful eradication of mink from Uist and Harris, to the whole of the Outer Hebrides archipelago, UK. They also highlight the potential for stable isotope approaches to provide more detailed postmortem information that can inform adaptive management of wildlife populations for conservation objectives.     

Timing of births and juvenile mortality in the South American fur seal in Peru

In most species, synchronous, seasonal reproduction is usually associated with higher offspring survival in animals giving birth around the peak, relative to those breeding at the extremes of the reproductive season. In contrast, in the South American fur seal ( Arctocephalus australis ) at Punta San Juan, Peru, females pupping around the peak of births had a greater probability of losing their pups and/or tended to lose them at an earlier age than females breeding early or late in the season. However, the timing of breeding in this population varies little between years and is consistently synchronous. Individual females maintained their relative breeding times in consecutive years, regardless of whether or not they lost their pup the previous year. Thus, pup mortality seems to have no effect on the timing of reproduction in this population.
High breeding densities and the consequent high pup mortality in the S. American fur seal in Peru may have resulted from intense poaching outside protected areas and are of recent origin. The reproductive synchrony in this population could have originally evolved as a response to seasonal variations in food availability and weather conditions, differences in female or pup body condition, predation pressure, sexual selection and/or harassment avoidance, but at the present high density levels has become maladaptive.     

Natural mortality of puffadder shysharks due to Cape fur seals and black‐backed kelp gulls at Seal Island, South Africa

Natural mortality of puffadder shysharks Haploblepharus edwardsii due to two species of marine tetrapod, the Cape fur seal Arctocephalus pusillus pusillus and the black‐backed kelp gull Larus dominicanis vetula , is reported. These data constitute the first multiple observations of natural mortality of any cartilaginous fish due to object play or kleptoparasitism by marine tetrapods. Evidence of range extension of the puffadder shyshark to False Bay, South Africa is presented.     

Behavioural responses of marine poikilotherms to pollutants.

Selected behavioural responses of marine fishes and invertebrates which are reportedly capable of disruption or impairment by petroleum, heavy metals, pesticides and other pollutants are listed. The usefulness of these and other performance functions to regulatory agencies charged with formulation of saline water quality criteria appears somewhat limited. At present, however, motor funcitons such as swimming performance, locomotion, and equilibrium, as well as physiological responses, especially respiratory patterns, may have some potential for biomonitoring of wastes discharged into coastal environments.     

Behavioural responses of a south-east Australian floodplain fish community to gradual hypoxia

1. Hypoxic conditions occur frequently during hot, dry summers in the small lentic waterbodies (billabongs) that occur on the floodplains of the Murray‐Darling River system of Australia. Behavioural responses to progressive hypoxia were examined for the native and introduced floodplain fish of the Ovens River, an unregulated tributary of the Murray River in south‐east Australia. 2. Given the high frequency of hypoxic episodes in billabongs on the Ovens River floodplain, it was hypothesised that all species would exhibit behaviours that would confer a degree of hypoxia‐tolerance. Specifically, it was hypothesised that as hypoxia progressed, gill ventilation rates (GVRs) would increase and aquatic surface respiration (ASR) would become increasingly frequent. Fish were subjected to rapid, progressive hypoxia from normoxia to anoxia in open tanks. 3. All tested species exhibited behaviours consistent with their use of potentially hypoxic habitats. As hypoxia progressed, GVRs increased and all species, with the exception of oriental weatherloach, began to switch increasingly to ASR with 90% of individuals using ASR at various oxygen concentrations below 1.0 mg O₂ L⁻¹. Australian smelt, redfin perch and flat‐headed galaxias were the first three species to rise to ASR, with 10% of individuals using ASR by 2.55, 2.29 and 2.21 mg O₂ L⁻¹ respectively. Goldfish and common carp were the last two species to rise to ASR, with 10% of individuals using ASR by 0.84 and 0.75 mg O₂ L⁻¹ respectively. In contrast to other species, oriental weatherloach largely ceased gill ventilation and used air‐gulping as their primary means of respiration during severe hypoxia and anoxia. 4. Australian smelt, redfin perch and flat‐headed galaxias were unable to maintain ASR under severe hypoxia, and began exhibiting erratic movements, termed terminal avoidance behaviour, and loss of equilibrium. All other species continued to use ASR through severe hypoxia and into anoxia. Following a rise to ASR, GVRs either remained steady or decreased slightly indicating partial or significant relief from hypoxic stress for these hypoxia‐tolerant species. 5. Behavioural responses to progressive hypoxia amongst the fish species of the Ovens River floodplain indicate a generally high level of tolerance to periodic hypoxia. However, species‐specific variation in hypoxia‐tolerance may have implications for community structure of billabong fish communities following hypoxic events.     

Behavioural and sensory responses to some neem compounds by Pieris brassicae larvae

Abstract. The efficacy of a commercial product (Margosan-O) to inhibit feeding in Pieris brassicae L. (Lepidoptera: Pieridae) larvae was compared to that of three pure triterpenoids of botanical origin: azadirachtin and salannin (occurring in Melia azedurach ), and toosendanin (occurring in M. toosendan ). In dual-choice behaviour tests the order of antifeedant efficacy was: Margosan-O > toosendanin > salannin > azadirachtin. The ranking order of their capacity to stimulate the deterrent receptor located in the medial sensillum styloconicum appears to be: Margosan-O = toosendanin > salannin > azadirachtin. In addition to stimulating the medial deterrent cell, toosendanin inhibits the sugar receptor and the glucosinolate receptor, both located in the lateral sensillum styloconicum. The amino acid receptor in this sensillum, however, is not affected. In contrast, neither azadirachtin nor salannin influences the sensitivity of any of the receptor cells in this sensillum.
The adaptation rate of the deterrent receptor is low in comparison to that of the two sugar receptors.
A significant correlation is found between the antifeedant indices of the four neem compounds tested at three different concentrations, and the responses of the deterrent receptor to these compounds at similar concentrations. It is concluded that when this insect species feeds on its natural foodplant (i.e. cabbage), the deterrent effect of neem compounds is mediated solely via the medial deterrent receptor, whereas inhibitory effects on the sugar and glucosinolate receptors do not play a significant role.     

Behavioural responses to visual stimuli by the snail Littorina irrorata

The visual capabilities of gastropod molluses and most other invertebrates possessing structurally simple eyes are poorly known. We studied vision in untrained marsh periwinkles (Littorina irrorata) in the laboratory, using oriented movements toward test shapes as the response measure. This intertidal species is active when exposed at low tide, both during the day and at night, and it travels vertically on plant stems with a tidal rhythm. In detection tests, the estimated response threshold for a single vertical bar was 0.9°, while the response threshold for an equal-size horizontal bar was 2.4° or 3.7°, depending on bar position. Snails detected a 5°-wide bar in 4.3 1x of light and a 40°-wide square having about 95% reflectance (‘off-white’) on a white (100% nominal reflectance) background in 2800 1x. Discrimination tests revealed a strong preference for vertical bars over both diagonal and horizontal bars of the same width, but no preferences in several other situations. Various factors suggest that L. irrorata may see better than most other gastropods.