Wild Pups Research Articles

Variability in Body Condition and Growth Rates for Rehabilitated Harbor Seal (Phoca vitulina) Pups

In the United States, Canada, and Europe harbor seal (Phoca vitulina) pups are commonly rehabilitated after stranding and then released. Size at release is likely important to post-release survival; however, data have not been compiled to track the body condition of rehabilitated harbor seals at release across the U.S. To better understand spatiotemporal variations in harbor seal morphometrics during rehabilitation and at release, this study retrospectively analyzed body conditions, weights, lengths, and growth rates of rehabilitated harbor seal pups in the U.S. Body condition index (BCI) was calculated, and weight and BCI were modeled regionally and temporally. There was significant variation in weight, length, BCI, and growth rate for rehabilitated and released seals between the East and West Coasts of the U.S. and among different years. Growth rates during rehabilitation were slower than reported for wild pups from birth to weaning. Length at release was not a strong predictor of weight. Because animals of similar weights can have different lengths, weight alone might not be the best criterion for pre-release body condition. A body condition score incorporating weight, length, and possibly other variables such as age or axillary girth could be more informative; however, data on post-release survival are needed to evaluate these options.

Differences in the Activities of Serum Antioxidant and Immune Factors between Wild and Captive Spotted Seal (Phoca largha) Pups from the Liaodong Bay Colony

The innate immune system plays a vital role to resist the environmental stresses and infectious pathogens in marine mammal pups. To get a baseline level of innate immune capacity in spotted seals, the concentrations of several antioxidant and immune-related factors in the serum of wild and captive spotted seal (Phoca largha) pups from the Liaodong Bay colony were measured and compared. Cu/Zn superoxide dismutase and peroxidase were mainly responsible for the antioxidant system of spotted seal pups, and wild pups possessed stronger antioxidant capacity than captive ones. Against infectious pathogens, wild spotted seal pups also had an advantage over the captive counterparts. Specifically, the activities of acid phosphatase, phenoloxidase, and lysozyme in the serum of wild spotted seal pups were significantly higher than those in captive animals. The present study provides the normal activities of several serum immune enzymes for wild and captive spotted seal pups from the Liaodong Bay colony, which is benefit to the conservation of this species.

OPN receptor expression on immune effector cells in RSV infection is regulated by NKT cells

Abstract RSV infection in early life predisposes to asthma later in life. Role of aberrant immune responses to childhood viral infections is well documented. Involvement of myeloid (mDC) and plasmacytoid (pDC) Dendritic Cells (DC) and Natural Killer T-cells (NKT) has been reported. Osteopontin (OPN) modulates the immune responses to viral infections. The current studies looked into the role of NKT cells in regulating the OPN receptor expression in RSV infection on DC, T and B cells, which will elucidate the role of OPN in preventing RSV-induced hyper-reactive airway and asthma. Five-day-old BALB/C and NKT−/−(CD1d−/−) mice were infected intranasally with RSV; and expression of OPN receptors (CD44 and CD51/61) were examined at designated post-infection days on lung mDC (CD11blo/−CD11chiCD45Rlo/−), pDC (CD11blo/−CD11clo/−CD45Rhi), T (CD3+) and B (CD19+) cells by flow cytometry. Expression of CD44 and CD51/61 were decreased on mDC, pDC, T and B cells in RSV infected wild pups compared to the control pups. On the other hand, OPN receptor expression was enhanced in the RSV-infected NKT−/− pups compared to the infected wild pups and uninfected NKT−/− pups suggesting a regulatory role of NKT cells on expression of OPN receptors, as RSV-infected NKT−/− pups had significantly increased CD44 and CD51/CD61 expression on DC and lymphocytes. Thus, decreased OPN receptor expression during RSV infection very likely diminishes the action of endogenous OPN allowing skewed polarization of DC and subsequent T cell responses. Therefore, abolishing the action of NKT cells to augment the action of endogenous OPN; and/or administration of exogenous OPN warrant further investigation as a new therapeutic strategy against RSV-associated asthma.

Harbor seal pup dispersal and individual morphology, hematology, and contaminant factors affecting survival

AbstractUnderstanding the factors affecting individual harbor seal (Phoca vitulina) survival is essential for determining population level health risks. We estimated postweaning dispersal, and modeled the effects of morphology, hematology, and blubber contaminants on the survival of recently weaned harbor seal pups using a mark recapture framework. We deployed satellite transmitters on apparently healthy pups captured in San Francisco Bay (SFB, n = 19) and Tomales Bay (TB, n = 7), and pups released after rehabilitation that stranded along the central California coast preweaning (n = 21). Dispersal distances were further than previously reported for harbor seal pups (maximum = 802 km) which has implications for understanding risks to this vulnerable age class. We found differences in body condition, serum immunoglobulin and thyroxine (T4) concentrations, white blood cell count, and blubber organohalogen contamination (OH) among the three groups. Overall, increased T4, decreased OH, and increased mass were associated with greater survival probabilities; whereas, among stranded seals, greater mass gain, shorter time in rehabilitation, and admission to rehabilitation earlier in the season were associated with greater survival probabilities. Attention to these latter factors may improve the success of rehabilitation efforts. For wild pups, reduction of legacy contaminants and direct causes of mortality, such as ship strike, may enhance pup survival.

Diving Related Changes in the Blood Oxygen Stores of Rehabilitating Harbor Seal Pups (Phoca vitulina).

Harbor seal (Phoca vitulina) pups begin diving within hours of birth, stimulating the development of the blood oxygen (O2) stores necessary to sustain underwater aerobic metabolism. Since harbor seals experience a brief nursing period, the early-life development of these blood O2 stores is necessary for successful post-weaning foraging. If mothers and pups become prematurely separated, the pup may be transported to a wildlife rehabilitation center for care. Previous studies suggest that the shallow pools and lack of diving in rehabilitation facilities may lead to under-developed blood O2 stores, but diving behavior during rehabilitation has not been investigated. This study aimed to simultaneously study the diving behaviors and blood O2 store development of rehabilitating harbor seal pups. Standard hematology measurements (Hct, Hb, RBC, MCV, MCH, MCHC) were taken to investigate O2 storage capacity and pups were equipped with time-depth recorders to investigate natural diving behavior while in rehabilitation. Linear mixed models of the data indicate that all measured blood parameters changed with age; however, when compared to literature values for wild harbor seal pups, rehabilitating pups have smaller red blood cells (RBCs) that can store less hemoglobin (Hb) and subsequently, less O2, potentially limiting their diving capabilities. Wild pups completed longer dives at younger ages (maximum reported <25 days of age: 9 min) in previous studies than the captive pups in this study (maximum <25 days of age: 2.86 min). However, captivity may only affect the rate of development, as long duration dives were observed (maximum during rehabilitation: 13.6 min at 89 days of age). Further, this study suggests that there may be a positive relationship between RBC size and the frequency of long duration dives. Thus, rehabilitating harbor seal pups should be encouraged to make frequent, long duration dives to prepare themselves for post-release foraging.

Postrelease movement of rehabilitated harbor seal (Phoca vitulina richardii) pups compared with cohort‐matched wild seal pups

AbstractHarbor seal (Phoca vitulina richardii) populations in the inland waters of Washington and British Columbia are at or near carrying capacity. Stranded pups often are collected and admitted to rehabilitation centers, and then released when they reach a weight of 22 kg and meet a variety of preestablished health and release conditions. While rehabilitation is common practice, it is unclear if rehabilitated seal pups behave like wild weaned pups. Using satellite transmitters, we compared movement patterns of 10 rehabilitated pups with 10 wild weaned pups. When released, rehabilitated seals were longer and heavier than wild pups, while wild pups had a larger mean axillary girth. No clinically different blood parameters were detected. On average, rehabilitated harbor seal pups traveled nearly twice as far cumulatively, almost three times as far daily, and dispersed over three times as far from the release site compared to wild weaned seals. Additionally, wild harbor seals transmitted nearly twice as long as did rehabilitated seals. These patterns suggest that learned behavior during the brief 3–4 wk nursing period likely enables wild harbor seal pups to move less daily and remain closer to their weaning site than rehabilitated pups.

HEMATOLOGY AND SERUM CHEMISTRY IN STRANDED AND WILD-CAUGHT HARBOR SEALS IN CENTRAL CALIFORNIA: REFERENCE INTERVALS, PREDICTORS OF SURVIVAL, AND PARAMETERS AFFECTING BLOOD VARIABLES

Blood was collected from stranded harbor seal (Phoca vitulina) pups at admission (n=64) and release (n=45) from rehabilitation in 2007 and 2008 and from wild-caught harbor seal pups, subadults, and adults (n=110) in 2004, 2007, and 2008. Blood values measured at the time of admission were not predictive of survival during rehabilitation. Mass was associated with survival until release, and all pups that died weighed less than 10 kg at the time of admission. Döhle bodies were observed in leukocytes from 15% to 22% of the pups in rehabilitation, but not in the wild pups. Thresholds (95% confidence intervals) among wild pups were less than those in the released pups for leukocytes, neutrophils, total cholesterol, alanine aminotransferase (ALT), glucose, phosphorus, sodium, potassium, total protein, albumin, and globulin; thresholds were greater in wild pups than in released pups for hemoglobin (HGB), hematocrit (HCT), and glucose. Thresholds among released pups were less than those in wild pups for HGB, HCT, mean cell volume, chloride, and creatine kinase; thresholds among released pups were greater than those in wild pups for neutrophils, platelets, total cholesterol, triglycerides, ALT, aspartate aminotransferase, sorbitol dehydrogenase, bilirubin, phosphorus, potassium, total protein, and albumin. Age, girth, and geographic location affected the blood variables from wild-caught pups; age class, geographic location, sex, and body condition affected the blood variables of wild-caught, subadult and adult harbor seals.

The responsiveness of young rabbits to the mammary pheromone: developmental course in domestic and wild pups

Newborn rabbits rely on odour cues to localize and seize maternal nipples. In particular, they orally respond to the mammary pheromone (MP) emitted in rabbit milk. The activity of the MP was so far mainly investigated in newborns, and a drop in its releasing effect was shown in 23-day old pups. Here, we evaluated the activity of the MP in a large sample (n=1588) of domestic rabbit pups tested between birth and weaning. We also assessed whether wild-type pups respond to the MP, and whether the developmental course of their responsiveness matches the one of domestic pups. During the first postnatal week, the MP revealed to be a strong releasing stimulus in all pups, regardless of their genetic and environmental background. However, the saliency of the MP decreased with approaching weaning, and this decrease was clearly steeper in wild-type than in domestic pups. These results are discussed with regard to the concept of ontogenetic adaptation and the effects of artificial selection.

Behavior, Movements, and Apparent Survival of Rehabilitated and Free-Ranging Harbor Seal Pups

Post-release studies are essential to determine the efficacy of wildlife rehabilitation. Although an increasing number of Pacific harbor seal (Phoca vitulina richardsi) pups are admitted to rehabilitation centers, few studies have been conducted to monitor the behaviors and survival of rehabilitated pups released back into the wild. Our objectives were to compare diving behaviors, activity patterns, movements, and survival between rehabilitated pups (n = 29) and wild pups (n = 24). Pups were radiotracked for 5 months after release at Pebble Beach, California, during 1995, 1996, and 1998. Mean duration of dives (t 27 = 0.90, P = 0.37) and surface intervals (U = 52, P = 0.20) of rehabilitated pups did not differ from that of wild pups. Rehabilitated pups spent a greater proportion of their time in the water (t 18 = 2.12, P= 0.047) than did wild pups. Most pups traveled north from Pebble Beach, and movements were variable. Seal group (F 1 31 = 1.33, P= 0.26) or sex (F 1 31 = 0.22, P= 0.64) had no effect on maximum distance traveled. Survival curves between rehabilitated and wild pups were similar during 1995 (X 2 = 0.40, P> 0.05) and 1998 (X 2 = 1.34, P> 0.05), whereas rehabilitated pups had lower survival than wild pups during 1996 (X 2 = 3.94, P 0.05). In summary, the overall behavior, movement, and apparent survival of rehabilitated pups appeared similar to wild pups. Future studies should be conducted to assess the long-term survival of rehabilitated and free-ranging harbor seal pups.

Weights, Growth, and Survival of Timber Wolf Pups in Minnesota

Weights, growth rates, canine tooth lengths, and survival data were obtained from 73 wild wolf ( Canis lupus ) pups that were 8 to 28 weeks old when live-trapped in three areas of northern Minnesota from 1969 to 1972. Relative weights of wild pups are expressed as percentages of a standard weight curve based on data from captive pups of similar age. These relative weights varied greatly within litters, between litters, and between years; extremes of 31 to 144 percent of the standard were observed. Growth rates ranging from 0.05 to 0.23 kilograms per day were observed, and similar variations in general development and in replacement and growth of canine teeth were noted. Survival data based on radio-tracking and tag returns indicated that pups with relative weights less than 65 percent of standard have a poor chance of survival, whereas pups of at least 80 percent of standard weight have a high survivability. Pups born in 1972 were especially underweight, probably a result of declining white-tailed deer ( Odocoileus virginianus ) densities in the interior of the Superior National Forest study area.