Joseph R. Waas

Effects of human approaches to nests of northern New Zealand dotterels

The northern New Zealand dotterel Charadrius obscurus aquilonius is an endangered shorebird, and it is thought that human disturbance may decrease its nesting success. We made three types of approach to nests (walking, running or leading a dog). We measured the flush distance, length of time parents spent off the nest and distraction display intensity. Leading a dog caused the greatest disruption of incubation, while responses to walking and running approaches did not differ significantly. Distraction display intensity appeared to be unrelated to approach type. There was evidence of habituation to humans on busy beaches. Our results provide the first experimental evidence that shorebirds perceive dogs as posing more of a threat than humans on foot, and that their subsequent avoidance response is greater. We recommend that human activity, particularly the walking of dogs, should be limited near nesting sites. Further study on causes of nest failure is required.

Considerations on the use of video playbacks as visual stimuli: The Lisbon workshop consensus

Abstract This paper is the consensus of a workshop that critically evaluated the utility and problems of video playbacks as stimuli in studies of visual behavior. We suggest that video playback is probably suitable for studying motion, shape, texture, size, and brightness. Studying color is problematic because video systems are specifically designed for humans. Any difference in color perception must lead to a different color sensation in most animals. Another potentially problematic limitation of video images is that they lack depth cues derived from stereopsis, accommodation, and motion parallax. Nonetheless, when used appropriately, video playback allows an unprecedented range of questions in visual communication to be addressed. It is important to note that most of the potential limitations of video playback are not unique to this technique but are relevant to all studies of visual signaling in animals.

The effects of long-term honey, sucrose or sugar-free diets on memory and anxiety in rats

Sucrose is considered by many to be detrimental to health, giving rise to deterioration of the body associated with ageing. This study was undertaken to determine whether replacing sucrose in the diet long-term with honey that has a high antioxidant content could decrease deterioration in brain function during ageing. Forty-five 2-month old Sprague Dawley rats were fed ad libitum for 52 weeks on a powdered diet that was either sugar-free or contained 7.9% sucrose or 10% honey (which is the equivalent amount of sugar). Anxiety levels were assessed using an Elevated Plus Maze, whilst a Y maze and an Object Recognition task were used to assess memory. Locomotor activity was also measured using an Open Field task to ensure that differences in activity levels did not bias results in the other tasks. Anxiety generally decreased overall from 3 to 12 months, but the honey-fed rats showed significantly less anxiety at all stages of ageing compared with those fed sucrose. Honey-fed animals also displayed better spatial memory throughout the 12-month period: at 9 and 12 months a significantly greater proportion of honey-fed rats recognised the novel arm as the unvisited arm of the maze compared to rats on a sugar-free or sucrose-based diet. No significant differences among groups were observed in the Object Recognition task, and there appeared to be no differences in locomotor activity among groups at either 6 or 12 months. In conclusion, it appears that consumption of honey may reduce anxiety and improve spatial memory in middle age.

Three-dimensional dive profiles of free-ranging Weddell seals

Abstract We used an acoustic tracking system to record under-ice movements of two free-ranging adult male Weddell seals. The two males were unconstrained and interacting with other Weddell seals at a breeding colony in McMurdo Sound, Antarctica. We reconstructed three-dimensional paths of 279 dives by these seals. All dives were less than 20-min duration and none were deeper than 220 m. These three-dimensional dive profiles were compared with conventional time-depth dive profiles recorded using microprocessor loggers. We assigned each of the 279 dives to 1 of 6 classes using an existing classification scheme on the basis of the time-depth trace. Within these, two-dimensionally derived, classes the actual three-dimensional dive profiles at times varied profoundly. Additional parameters obtained with the acoustic system, such as bearing and distance travelled between diving and surfacing points, demonstrate that significant, additional, biologically important information can be derived from the three-dimensional data.

Effects of human activity on the behaviour of northern New Zealand dotterel Charadrius obscurus aquilonius chicks

Human disturbance is one of the factors that may contribute to low breeding success in the endangered New Zealand dotterel Charadrius obscurus aquilonius. This study examined how foraging and related behaviours of northern New Zealand dotterel chicks were affected by human presence. Chicks were observed both in the presence, and in the controlled absence, of people. Results showed that, when people were present, chicks spent less of their feeding time in the littoral zone, and more in the supralittoral zone, and in general spent less time feeding when people were present. These data suggest that the littoral zone may be more desirable for foraging than is the supralittoral zone, and that high levels of human disturbance may infer energetic constraints on New Zealand dotterel chicks. Fledging success of chicks may be enhanced if human access to feeding areas adjacent to breeding sites is reduced during the chick-rearing phase of the breeding season.

‘O sibling, where art thou?’ – a review of avian sibling recognition with respect to the mammalian literature

Avian literature on sibling recognition is rare compared to that developed by mammalian researchers. We compare avian and mammalian research on sibling recognition to identify why avian work is rare, how approaches differ and what avian and mammalian researchers can learn from each other. Three factors: (1) biological differences between birds and mammals, (2) conceptual biases and (3) practical constraints, appear to influence our current understanding. Avian research focuses on colonial species because sibling recognition is considered adaptive where‘mixing potential’of dependent young is high; research on a wide range of species, breeding systems and ecological conditions is now needed. Studies of acoustic recognition cues dominate avian literature; other types of cues (e.g. visual, olfactory) deserve further attention. The effect of gender on avian sibling recognition has yet to be investigated; mammalian work shows that gender can have important influences. Most importantly, many researchers assume that birds recognise siblings through‘direct familiarisation’(commonly known as associative learning or familiarity); future experiments should also incorporate tests for‘indirect familiarisation’(commonly known as phenotype matching). If direct familiarisation proves crucial, avian research should investigate how periods of separation influence sibling discrimination. Mammalian researchers typically interpret sibling recognition in broad functional terms (nepotism, optimal outbreeding); some avian researchers more successfully identify specific and testable adaptive explanations, with greater relevance to natural contexts. We end by reporting exciting discoveries from recent studies of avian sibling recognition that inspire further interest in this topic.

Real-time physiological responses of red deer to translocations

To identify events or processes that may compromise the condition and welfare of wild or domesticated mammals during translocations (herding, pretransport confinement, loading, road transport, off-loading, posttransport confinement), red deer stags (Cervus elaphus) were outfitted with unique, remote blood-sampling and heart-rate devices and monitored in real time. Animals were translocated and monitored again on 2 further occasions (after 1-week recovery periods) to determine if red deer would habituate to such processes. Heart rates and levels of haematocrit and lactate rose during the initial herding and penning phase, and again during transitional events such as loading onto the transporter and, to a lesser extent, off-loading. Red deer may find these transitional events (that involve additional handling) more aversive than other parts of the process. A near linear, 3-fold increase in cortisol during the course of translocations suggested red deer became progressively stressed as time passed (sodium levels also increased, suggesting red deer became slightly dehydrated as well). In comparison, glucose and magnesium levels remained stable. The recorded changes are important because high adrenal activity is associated with an increase in an animals susceptibility to infectious diseases and may also result in the activation of latent infections, particularly in wild animals. Red deer showed little sign of habituating (or sensitizing) to repeated translocations (with the exception of small changes in haematocrit and glucose). ). Managers may reduce health and welfare problems associated with translocation by limiting the number and aversiveness of transitional events. Translocations should also be as short as possible, but longer trips could include short breaks (approx 40 min) in dark, cool environments to settle animals. Managers should ensure access to water and only translocate animals that are in good condition and outside of any sensitive phases of their life cycle (e.g., reproductive period).

Low genetic variability in small populations of New Zealand kokako Callaeas cinerea wilsoni.

The endangered kokako Callaeas cinerea wilsoni (Callaeidae), an endemic forest-dwelling passerine of New Zealand, has declined over the last century to a number of small isolated populations due to widespread habitat clearance and predation by introduced predators. To evaluate the genetic consequences of inbreeding and genetic drift, we examined genetic variability within and among 3 of the major remaining kokako populations using 4 polymorphic microsatellite loci. The largest remaining kokako population in the Te Ureweras was shown to have greater variability than the smaller Mapara and Rotoehu populations. Differentiation among the populations was low to moderate. We suggest there is no genetic barrier to translocations between the populations and that translocations of some individuals between the remaining kokako populations could enhance genetic variability of small populations to levels found in larger populations (e.g. Te Ureweras).

Paternity analysis shows experience, not age, enhances mating success in an aquatically mating pinniped, the Weddell seal (Leptonychotes weddellii)

For polygynous mammals with no paternal care, the number of offspring sired is often the sole measure of male reproductive success. The potential for polygyny is highest when resources or other environmental factors such as restricted breeding sites force females to aggregate. In these circumstances, males compete intensely for females and mating success may vary greatly among males, further intensifying selection for those traits that confer an advantage in reproduction. Hence, determinants of male success in competition for females are likely to be under strong sexual selection. Paternity analysis was used in conjunction with measures of age, site fidelity, and behavior during the breeding season to assess variance in male breeding success in Weddell seals (Leptonychotes weddellii) breeding at Turtle Rock, McMurdo Sound (77.727S, 166.85E) between 1997 and 2000. Paternity could be assigned to 177 pups at relaxed or 80% confidence level or 111 pups at strict or 95% confidence levels. Weddell seals at Turtle Rock show a modest degree of polygyny with the greatest number of pups sired by any individual male in a single season equalling 5 or ∼10% of the pups born. Over four consecutive years, most (89.2%) males sired at least one pup. In a generalized linear model (GLM), age and the age first seen at the study site as an adult were unrelated to mating success, but adult experience, either site-specific or elsewhere in McMurdo Sound, over the reproductive life span of males explained nearly 40% of variance in total mating success with 80% confidence and 24% of variance at 95% confidence. While learning where females are likely to be may enhance male reproductive success, aquatic mating reduces the ability of males to monopolize females, and thereby increases equity in mating success.

Laboratory and field evaluation of predator odors as repellents for kiore (Rattus exulans) and ship rats (R. rattus)

Predator odors may serve to stop rats from entering conservation areas or to decrease predation, food consumption, and other damage by rats in areas tainted with predator odor. We compared the efficacy of real predator odors and synthetic odors (derived from the urine and feces of carnivores) as rat repellents with real herbivore odors as controls in a Y maze. We tested six predator odors: cat (Felis catus) urine and feces, mongoose (Herpestes auropunctatus) feces, n-propylthietane, S-methyl, methyl butanol, and isopentyl-methyl sulphide. The herbivore odors we used were: red deer (Cervus elaphus) urine, guinea pig (Cavia porcellus) feces, and white rabbit (Oryctolagus cuniculus) urine. Ship rats (Rattus rattus) and kiore or Polynesian rats (R. exulans) showed no aversion to any of the six predator odors when compared with herbivore odors. Ship rats, however, may have avoided synthesized odors more than real ones. We applied two odors (S-methyl, methyl butanol and n-propylthietane) to purpose-built feeders in native forest but recorded no change in either visitation rate or duration of visits for rodents [rats and mice (Mus musculus)] or possums (Trichosurus vulpecula). The consumption of maize at feeders was correlated with the number and duration of possum visits, but only weakly correlated with the number of visits by rodents. Consumption of maize was unaffected by the odor associated with the feeder. It is unlikely that the odors we tested will be useful in deterring rodents or possums from areas where they have been removed for economic, public health or conservation reasons.