Time In Shelter Research Articles

Egg size and food abundance interactively affect juvenile growth and behaviour

Summary 1. Comparative evidence from several animal taxa suggests that juveniles hatching from larger eggs have fitness benefits when growing up in a harsh environment, whereas under benign conditions egg size should be of less importance. However, the physiological and behavioural mechanisms responsible for these context‐dependent fitness differences are as yet poorly understood. 2. We studied the interactions between the phenotype of developing offspring and their environment in the mouthbrooding cichlid Simochromis pleurospilus. We hand‐raised young from large and small eggs, and measured their initial body size and burst swimming speed. Thereafter we raised half of each egg‐size class on high and half on low food ration and followed their growth trajectories and behavioural development until the age of 12 weeks. 3. We found that larger eggs gave rise to larger young that had a higher burst swimming speed. Food ration greatly influenced long‐term growth, while egg size predominantly affected fish size during the first 2 weeks of life. However, large egg size caused a size advantage of juveniles persisting throughout the experimental period. 4. Egg size and food ration interactively affected the hiding and foraging behaviour of young. In the low‐food treatment, individuals from small eggs spent less time in shelter and showed a higher commitment to foraging than individuals from large eggs. In a natural setting, this should markedly increase predation risk of young originating from small eggs, particularly in poor environments. In contrast, when food was plentiful juveniles behaved similarly, irrespective of egg size. 5. Our results show that egg size affects juvenile growth trajectories and behaviour differently in different environments. While it is well‐established that a large egg size raises offspring fitness particularly in harsh environments, our study suggests that this advantage arises through risk‐averse behaviour being tightly linked to offspring size.

Factors associated with vesicular stomatitis in animals in the western United States

To identify factors associated with development of vesicular stomatitis (VS). Case-control study. 138 livestock premises and 118 horses suspected of having VS in Texas, New Mexico, and Colorado. Premises with >or= 1 animal with clinical signs and laboratory confirmation of infection were classified as case premises. Premises where laboratory confirmation results were negative were control premises. Among equine premises, case and control horses were selected on the basis of premises status. A survey was conducted to identify factors associated with VS for premises and specific horses. Control of insect populations in the 2 weeks before the VS investigation decreased the odds of disease for premises where vegetation coverage was grassland or pasture (odds ratio [OR], 0.08; 95% confidence interval [CI], 0.01 to 0.7). Odds of VS for premises covered with grassland or pasture increased when measures to control insect populations were not used (OR, 11; 95% CI, 0.8 to 156.3) and for premises that had a body of water (OR, 2.3; 95% CI, 1.0 to 5.6). Use of measures to prevent insect bites or harassment by insects (OR, 0.2; 95% CI, 0.1 to 0.8) and spending time in shelters (OR, 0.4; 95% CI, 0.2 to 1.1) in the 2 weeks prior to investigation decreased the odds of being a case horse. Insect control and spending time in shelters decreased the odds for infection with VS. Premises covered with grassland or pasture or that had a body of water were at a higher risk.

Behavioral Correlates of Alternate Male Forms (Form I and Form II) in the Crayfish Orconectes Rusticus

Abstract Crayfishes belonging to the family Cambaridae occur in two adult male morphs, Form I which is reproductively competent and Form II which is nonreproductive. In our first experiment, we compared the behavior of Form I and Form II animals by measuring walking, sheltering, feeding, and attraction to a female conspecific in single male Orconectes rusticus. Our data demonstrated that, under laboratory conditions, Form II animals spent significantly more time in shelters than did Form I animals. The two forms did not differ significantly in the other measured behaviors. In our second experiment, we examined agonistic behavior in males of each form. When placed in intraform groups of four animals, Form II crayfish displayed fewer agonistic acts and spent less time fighting than did Form I males. In Form II males, increased sheltering may serve to reduce the risk of predation, and fewer agonistic acts may reflect a lower motivation to compete with other males.

Some factors influencing adoption of sheltered dogs

In Italy the law forbids euthanizing shelter dogs unless they are severely ill or dangerous. This has created a problem: many dogs are housed for long periods of time in shelters. It is important to the welfare of these dogs for us to find methods to increase successful adoption rates. The aim of this study was to evaluate the effect of different management factors such as the number of dogs in a pen, Temporary Adoption Programs (TAPs), and animal-owner-related characteristics on successful adoptions of kenneled dogs. The study included 763 dogs, 92 of whom were dogs showing behavioral problems. The age of the dogs upon arrival at the shelter was the most important determinant for length of stay, with younger dogs being adopted faster (Kruskal-Wallis, H = 150.27; df = 3; n = 733; p < 0.001). Dogs up to six months of age (n = 73) were adopted more quickly than older dogs (average length of stay: 1.4 vs. 6.4 months). The year of admittance was also significant since dogs who were admitted in a year in which more dogs were brought to the shelter spent more time in the shelter before being re-homed (Kruskal-Wallis, H = 96.18; df = 2; n = 733; p < 0.001). Dogs' gender had no effect on length of stay (Mann-Whitney, U = 64563; Z = 0.81; p = ns; n1 = 389; n2 = 344). Temporary Adoption Programs had a significant positive effect in reducing the return rate when the final adopter was the same person who had “temporarily” adopted the dog (Fisher exact test, p = 0.0063). Return rate was also associated with behavioral problems. Fearful dogs were returned more often than dogs with other problems (Fisher exact test, p = 0.029). It is concluded that, although young age is the most important factor leading to quick adoption, programs which include increased human interaction, and special training for dogs with behavioral problems, could aid in the successful re-homing of shelter dogs.

Assessing the magnitude of intra- and interspecific competition in two coral reef fishes

Many field experiments have tested for effects of competition in nature, but relatively few have used designs allowing simultaneous assessment of the influence of intra- and interspecific competition. Using a response surface design and a press manipulation of densities, we tested effects of competition within and between two species of coral reef fishes (Coryphopterus glaucofraneum and Gnatholepis thompsoni). By tracking individually tagged fishes, we showed that the per-capita effect of intraspecific competitors on individual growth was at least twice as great as the effect of interspecific competitors. Growth rate was better predicted by measures of density that incorporated body size, rather than numerical density, suggesting interference competition. Individuals of both species interacted aggressively with conspecifics at least twice as often as with heterospecifics. Individuals of both species also covered more area while foraging and spent less time in shelter when crowded than when at lower densities. In combination, these behaviours suggest that increased metabolic costs at high density contribute to competitive effects on growth. These competitive interactions occurred among adult fishes, so reduced growth may translate to reduced fecundity as well as reduced survival, and so contribute to population regulation.

Agonistic interactions between the invasive green crab, Carcinus maenas (Linnaeus) and juvenile American lobster, Homarus americanus (Milne Edwards)

Invasive organisms have the potential for competition with native organisms. In the Southern Gulf of St. Lawrence, juvenile American lobsters have a potential spatial overlap with adult green crabs. Crustaceans use agonistic behaviour to settle disputes, with the larger organism often winning contests for limited resources such as food and shelter. Two experiments were carried out using adult green crabs (53–76 mm carapace width) and juvenile American lobsters (28–57 mm carapace length). The first experiment used a limited food resource. We found that green crabs were the first to the food in all trials, fed in significantly more trials than lobsters and spent a significantly greater proportion of time with the food. The lobsters were only able to displace the green crabs from the food in 2 of 65 attempts. The second experiment was designed to examine shelter competition; unexpectedly some predation by green crabs on lobsters occurred, which allowed us to test hypotheses about how relative size and shelter use affect predation. Green crabs captured and consumed juvenile lobsters in 6 of 11 trials. The lobsters that survived spent significantly more time in shelter. There was no clear relationship between shelter use and size of lobster. The lobsters that were larger in relation to the green crabs suffered a higher rate of predation, which we believe was due to more conspicuous activity and less use of shelter. It appears that green crabs have the potential to negatively impact native juvenile lobster.

Exposure to variable spatial information in the early rearing environment generates asymmetries in social interactions in cod (Gadus morhua)

Many re-introduction programs used for conservation of populations and species threatened with extinction advocate the use of enriched rearing environments to train animals how to behave appropriately in the wild. Curiously, most of the current fish re-stocking programs have paid little attention to lessons previously learned in bird and mammal re-introductions. Many rehabilitation programs that use releases of hatchery fish observe higher mortality in released fish compared to wild, with most mortality arising shortly after release. One explanation for this mortality is based purely on selection processes; many hatchery fish normally selected out of the population thrive in the predator free, food-rich hatcheries. Alternatively, mortalities may be high because hatchery nursery environments fail to shape fish behaviour appropriately. Here, we empirically address the effect of enrichment in the early rearing environment in coastal cod (Gadus morhua). We find asymmetries in aggressive behaviour when fish reared in plain or enriched environments are allowed to interact. Furthermore, cod reared in standard, impoverished, hatchery environments spend less time in shelter, are more active, and show weaker anti-predator responses than fish reared with access to heterogeneous spatial cues. These results suggest that the constant, plain environments of fish farms may generate behavioural deficits that could reasonably be expected to be associated with lower survival in fish released into the wild.

Competitive Interactions between Round Gobies and Logperch

We examined territorial defense and behavioural interactions between two species of fish resident in Hamilton Harbour: non-indigenous round gobies ( Neogobius melanostomus) and native logperch ( Percina caprodes). Trials consisted of placing one fish, “the resident” (either a round goby or a logperch), in a tank with a shelter for 24 hours before adding another fish, “the intruder” (either a round goby or a logperch), and recording aggressive incidents. Overall, gobies exhibited more aggressive behavior than logperch, and in general resident status had no effect on amount of aggression displayed. Also, gobies spent more time in shelters than logperch, and overall resident status did not affect the amount of time spent under shelter. We also compared abundance data for gobies and logperch using electrofishing transects in Hamilton Harbour that were conducted in 1995 and 2001 and found a dramatic increase in round goby numbers and a non-significant decrease in logperch numbers. Our data suggest that gobies are superior space competitors and hence the range expansion coupled with an increasing population size of the round gobies in Hamilton Harbour is likely to have deleterious consequences for logperch populations.

Determinants of Adoption and Euthanasia of Shelter Dogs Spayed or Neutered in the University of California Veterinary Student Surgery Program Compared to Other Shelter Dogs

Limited economic resources and pet overpopulation force animals shelters to consider euthanasia of adoptable animals every day. Veterinary medical schools can play a positive role in increasing pet adoption and combating overpopulation by providing free neutering for shelter animals. This retrospective cohort study illustrated that the cooperative efforts of a veterinary medicine surgical teaching program and local animal shelters decreases euthanasia of adoptable pets. At the University of California, Davis (UCD), shelter dogs are neutered by veterinary students and then returned to the shelter for adoption. The rates of adoption and euthanasia of the dogs neutered at UCD were contrasted with a comparison shelter group to determine the effect of pre-adoption neutering. The UCD-neutered dogs had a lower rate of euthanasia than the comparison shelter group at the shelters investigated. At Sacramento County Animal Care and Regulation, 73% of the UCD group but only 36% of the comparison group were adopted. At Yolo County Animal Services, 71% of the UCD group and 45% of the comparison group were adopted. The sex of an animal did not significantly affect the rate of euthanasia. Dogs that were predominantly pit bull, rottweiler, or chow chow breeds had higher rates of euthanasia than other breeds, independent of neuter status. Also, juveniles (less than one year old) had lower rates of euthanasia than adults, independent of neuter status. UCD adult dogs had lower rates of euthanasia than comparison adults. Post-surgical UCD dogs spent a longer average time in the shelter before adoption (15 days at Sacramento; 16 days at Yolo) than the comparison dogs (11 and 12 days, respectively). UCD dogs also spent a longer average time in the shelter before euthanasia (18 and 25 days, respectively) than the comparison dogs (13 days at both shelters). Lower probabilities of euthanasia for behavioral or medical reasons were found for UCD dogs than for the comparison dogs. The probability of euthanasia for reasons of space limitations increased with time in shelter for both groups. In this study, pre-adoption neutering increased adoptions without increasing the probability of medical or behavioral euthanasia.

Adoption of Dogs in the Czech Republic

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Behavior, Growth and Survival of Stage V Lobsters (Homarus Americanus) in Relation to Shelter Availability and Lobster Density

The effects of 2 levels of shelter availability (8 or 32 shelters) and of 3 levels of intraspecific density (5, 15, or 30 individuals per 0.5 m 2) on the behavior, survival and growth of stage V lobsters over a period of h 25 days were examined through controlled laboratory experiments. Dominance interactions were apparent in all treatments and only certain lobsters gained access to shelter in the medium- and high-density treatments. Lobsters spent more than 95% of their time in shelter when possible, and expressed significantly greater fidelity to one shelter in the 8-shelter treatment compared to the 32-shelter treatment. Shelter availability and lobster density had no effect on the incidence of molting or on the mean size of lobsters at experiment's end. The proportion of injured lobsters was independent of shelter availability, but was positively related to density. Lobsters were most likely to die after having molted and percent mortality was significantly greater at low density and in the 32-shelter treatment than in other treatments, probably due to a stronger and more consistent dominance hierarchy. Overall, the findings suggest that settlers may interact, that the frequency and intensity of interactions may be modified by relative shelter availability and lobster density, and that such interactions may contribute to determine a cohort's fate.

Foraging in complex odor landscapes: chemical orientation strategies during stimulation by conflicting chemical cues

The concept of trade-offs and the decisions organisms make regarding them have become a driving force in ecological research. One well-studied trade-off, maximizing growth while minimizing mortality, affects decisions an organism makes regarding activity levels, habitat selection, and refuge use. Our study addressed how complex odor cues (e.g., a predation event and food combined) and their physical properties (e.g., concentration and spatial distribution) can affect foraging. Experiments were carried out using the crayfish Orconectes virilis in an artificial stream. A 2 × 2 factorial design was used with 2 odor treatments (food and food + alarm) and 2 shelter treatments (shelter and no shelter). Crayfish in the alarm treatment found the food source less often. They also took significantly longer to find the food source and spent more time in shelters. Crayfish in the presence of alarm stimuli used side shelters significantly more than shelters in the center of the flume, whereas crayfish in the control did not show a preference. Also, concentration of the alarm odor significantly affected the alarm response of the crayfish. Electrochemical recordings showed that the dopamine tracer was present in high concentrations down the center of the flume but in very low concentrations or absent along the sides of the flume for both the food and alarm trials. Our study illustrated the importance of chemical signals in aquatic systems for both locating food and avoiding predators. Complex odors influenced habitat use as well as foraging efficiency and success. The content, concentration, and distribution of complex chemical signals appear to be an important part of risk assessment during foraging, and may provide the necessary information to facilitate ecological interactions.

Sublethal effects of azamethiphos on shelter use by juvenile lobsters ( Homarus americanus)

The use of pesticides to treat sea lice infestations in aquaculture may have negative impacts on non-target organisms such as the American lobster ( Homarus americanus). Juvenile lobsters spend most of their time in shelter to avoid predation. This study examined: (1) whether the organophosphate pesticide azamethiphos affected shelter use by juvenile lobsters; (2) whether leaving shelter was a form of azamethiphos avoidance; and (3) whether azamethiphos affected shelter re-entry. The experiments were performed on juvenile lobsters (6.5–8 mm carapace length) in individual aquaria with an artificial shelter placed on a sand substrate. Azamethiphos concentrations of 0, 100, 500 and 1000 μg l −1 were used. Ten-minute short-term pulsed exposures to azamethiphos mimicking field conditions resulted in no shelter exits or lobster deaths. Under continuous exposure to azamethiphos, all lobsters left their shelters and the time to shelter exit and death decreased with increasing azamethiphos concentration. Survival of lobsters placed in fresh seawater following shelter exit was 100% for the 100 μg l −1 treatment, 50% for the 500 μg l −1 treatment and 33% for the 1000 μg l −1 treatment. Time to re-enter the shelter following exposure to azamethiphos was significantly shorter than the control for lobsters exposed to 100 μg l −1 and significantly longer than the control for lobsters exposed to 1000 μg l −1. Shelter exit appears to be a form of avoidance behavior to high concentrations of azamethiphos. At concentrations used by the aquaculture industry (100 μg l −1 and short exposure times), azamethiphos would not affect lobster shelter use. However, if the concentration or exposure time increased, mortality could occur directly due to this pesticide or indirectly as a consequence of leaving shelter.

The relationship of residential instability to medical care utilization among poor mothers in New York City.

This study examines the relationship between residential instability, including mobility and previous homelessness, and the use of medical care among previously sheltered and never-sheltered mothers in New York City. The study represents one of the first efforts to follow up on families after they are no longer homeless. Mothers from 543 welfare families in New York City were interviewed, once in 1988 (Time 1) and again beginning in 1992 (Time 2). The sample included 251 families who first entered shelters after their 1988 interview, and 292 families who spent no time in shelters before or after that point. Mothers were asked about the source and volume of medical care used in the year before follow-up. Bivariate and multivariate analyses showed that previously sheltered mothers had a greater reliance on emergency departments (EDs) and weaker ties to private physicians or health maintenance organizations (HMOs) than did mothers who never used shelters. Mobility before the Time 1 interview was associated with greater reliance on EDs and absence of a usual source of care. More recent mobility was not associated with a usual source of care. Current residential stability reduced the likelihood of using an emergency department or having no regular source of care. None of the measures of residential instability were related to the volume of outpatient care used by mothers. A history of residential instability, particularly previous shelter use, strongly predicts where poor mothers currently seek health care. Further research is needed to determine whether these patterns of health care use existed before mothers entered shelters. The study provides evidence that upon leaving shelters, mothers are not being well integrated into primary care services.

Comparative behaviour of two species of Lepadogaster (Pisces: Gobiesocidae) living at different depths

The two clingfish species studied occupied similar habitats but occurred at different depths. When compared with the subtidal species Lepadogaster candollei, the intertidal species Lepadogaster l. purpurea was less active, spent more time in shelters, visited fewer shelters, showed more site fidelity, and spent less time swimming. Feeding, swimming, and agonistic behaviours were performed mainly in close contact with the substrate in this species. It is hypothesized that these contrasts in behaviour may have evolved under different levels of turbulence.

Individual differences in homeless preschoolers' social behavior

The goal of this study was to investigate correlates of individual differences in homeless preschoolers' social behavior upon entry into a childcare setting. 49 (34 boys, 15 girls) 3- to 5-year-olds from homeless families participated. Families were residing in temporary shelters and were recruited during the child's intake into the daycare program. Parent interview data, teacher ratings of the children, standardized test scores, and videotaped observational data were obtained. Correlational analyses demonstrated individual differences in developmental status based, in part, on differences in homelessness. Results of correlational and regression analyses showed that significant variance in the child's social behavior was accounted for by measures of the child's temperament, developmental status, relationship with his/her parent and/or sibling, parental characteristics and indices of homelessness (e.g., length of time homeless, length of time in shelter). In particular, indices of homelessness predicted the child's social behavior above and beyond the more typical individual difference variables (e.g., temperament, developmental functioning, gender). Findings are discussed in terms of the effect of homelessness on the child's development and social experience.

Flexible responses to predators in a marine fish

The effect of predators on the behavior of signal blennies, Emblemaria hypacanthus (Pisces Chaenopsidae), was examined by comparing populations from two sites in the central Gulf of California that differed significantly in the abundance of predatory fishes. At the low-risk site the sexes differed in habitat use with males and females spending most of their time in shelters and in the open, respectively. At the high-risk site both sexes spent most of their time in shelters and also moved less and retreated into shelters more frequently than they did at the low-risk site. Both sexes fed at similar rates at the two sites, but their feeding efficiency was not measured. Males at the high-risk site courted females less vigorously and exhibited less intense courtship coloration than did males at the low-risk site. Although this difference in coloration was evident in the field over 3 consecutive years, males from both sites exhibited full courtship coloration in aquaria lacking predators. This implies that the ...

Field Observations of Social Behavior, Shelter Use, and Foraging in the Lobster, Homarus americanus.

Over a three-year period (1978-1981) behavioral observations of the lobster, Homarus americanus, were made by snorkeling in a shallow cove. Three hundred and thirty-four (334) animals were individually marked and this was the only time they were disturbed. In summer, the resident population numbered about 30 animals. The size composition, activity patterns, and habitat use of this population are described in a companion paper (Karnofsky et al., 1989). Shelters are of prime importance in the life of the lobster. Lobsters spent most of their time in shelters, leaving only at night. They dug shelters under eelgrass, rocks, and boulders; shelter locations appeared clustered. Some animals changed shelters frequently whereas others occupied the same shelters for up to 10 weeks. Premolt behavior was characterized by multiple shelter use. Cohabitation in the same shelter occurred only during periods of pair formation: when a mature female shared a male's shelter prior to and following her molt. We report the only field evidence for such courtship cohabitation. Food foraging behavior was rare (0.35 instances/observation hour); most foraging involved live prey. Similarly, intraspecific interactions were surprisingly infrequent (0.2 instances/observation hour) and most, by far, did not involve physical contact. Although puncture wounds suggested intraspecific aggression, actual observations of escalating fights were rare. Premolt residents were involved in 65% of the interactions observed. In 70% of the interactions the larger animal won. However, smaller males and females could successfully defend their shelters against larger females. We report results from three homing experiments. The results suggest that much of the time that resident lobsters spend outside shelters is used to remain familiar with their constantly changing physical and social environment.

Diel Activity and Foraging Behavior of Juvenile American Lobsters, Homarus americanus

The activity of wild-caught juvenile American lobsters, Homarus americanus (20–46 mm carapace length (CL)), was monitored in the laboratory using time-lapse video recording techniques. Behavioral time-budget analyses indicated that juvenile lobsters are nocturnally active within or close to available shelter. Mussels, Mytilus edulis, provided as prey were picked up, apparently nonselectively, when lobsters ventured out from shelter and were immediately taken back to shelter for consumption. Such shelter-related or central-place foraging behaviors may minimize risk from predation during transition to the wide-ranging activity pattern typical of larger lobsters. Increased hunger led to greater light-phase activity, primarily shelter-related foraging behavior, among individually monitored lobsters. Dominant lobsters in CL-matched pairs also exhibited this behavior pattern, but spent less time within shelter and feeding during dark phases due to involvement in agonistic interactions. Subdominant lobsters spent the least time in shelter, often remained inactive in open areas of tanks, and foraged predominantly during light phases. Increase in predation risk due to adoption of these behaviors may be the major consequence of subdominant status rather than a reduction in food intake.