Several weaknesses in our understanding of long‐lived animal populations have persisted, mainly due to a prevalence of studies of a single local population at the expense of multisite studies. We performed a multisite capture–mark–resight analysis using 2050 Atlantic Puffins (Fratercula arctica) banded as chicks on four islands (colonies) over 24 years in the Gulf of Maine, USA and Canada. Within program MARK, encounter, apparent survival, pre‐breeding movement (PBM; annual movements between colonies prior to breeding), and natal dispersal (ND) probabilities were modeled as functions of age, colony, and several covariates. Information‐theoretic model selection criteria and estimated model effect sizes were used to identify important effects and select models to estimate parameters. Encounter probabilities were extremely variable (0.10–0.95) and declined annually starting six years after bands were applied, due to changes in resighting effort, and band wear, respectively. Colony‐dependent survival probabilities increased to a peak at age six years; arithmetic means from all colonies were: 0.70 for age 0–3, 0.78 for age 4, 0.81 for age 5, and 0.84 for age 6–8 years. Low adult survival (age ≥5 years) may reflect inclusion of breeding and nonbreeding adults in our sample or a bias due to band loss and illegibility. Consistent with a density‐dependent prediction, the effect of colony size on survival was negative and acquired strong AICc support. However, this effect was inconsistent with strata effects in competing top models; the latter suggest that survival was lowest on the smallest island. The effects of origin and destination colony and origin colony size in PBM and ND probabilities resulted in important variation in these parameters. As few as 8% and as many as 57% of the puffins that we marked may have bred away from their natal colony, a signal of highly variable philopatry. Consistent with the conspecific attraction hypothesis, ND and PBM probabilities declined as the size of the origin colony increased. PBM probabilities were highest in the age 0–3 period, and these declined quickly with age thereafter. Strong colony and age effects in ND and PMB probabilities identify movement as a critical contributor to local population dynamics at our four study sites.
The slimy sculpin Cottus cognatus is an abundant and widespread benthic fish that inhabits cold lakes and rivers in North America. The objective of this study was to estimate survival and detection probabilities for slimy sculpin in relation to several environmental and biological predictors. Passive integrated transponder (PIT) tags were implanted into 337 adult slimy sculpin in five tributaries of the Kennebecasis River, New Brunswick, Canada. A portable PIT tag antenna was used to search for marked individuals from June 2003 to July 2004. Cormack–Jolly–Seber open population models were used to test several predictions and to estimate apparent survival and detection probabilities. We found that survival was high (73–99%) among sampling events; the average period was about 4 weeks (range, <1–22 weeks). Survival was positively related to fish length and negatively related to maximum stream discharge. The mean detection probability of tagged sculpin was 0.80, but it varied among sampling events and with respect to the minimum electrical current of our antenna and the percentage of boulder substrate at the site. This study demonstrates that a portable PIT tag system can be used in conjunction with capture–mark–recapture models to acquire an understanding of the basic life history characteristics of slimy sculpin and possibly other small‐bodied fish in freshwater systems.
Measuring daily and seasonal patterns of activity is useful for understanding the ecological and evolutionary drivers of behavior. We used collar-mounted light loggers to examine how nest attendance in arboreal squirrels and aboveground activity in semifossorial ground squirrels are affected by weather-driven changes in thermoregulatory conditions. Activity of lactating red squirrels (Tamiasciurus hudsonicus) had a diurnal pattern showing 3 daily peaks of activity with time spent outside the nest increasing with increasing ambient temperature, but decreasing with increasing relative humidity and wind. Despite the persistence of daylight during midsummer in the arctic environment, female arctic ground squirrels (Urocitellus parryii) also exhibited diurnal activity patterns with time spent above ground each day decreasing in response to precipitation but increasing with increasing ambient temperature and incident solar radiation. On cooler days, ground squirrels exhibited a unimodal activity pattern. However, on warm days, ground squirrels spent less time above ground when solar radiation and ambient temperature were both at their daily maxima, which resulted in a bimodal activity pattern. Our results highlight the utility of light loggers as a cost-effective means of addressing questions related to foraging behavior, parental care, thermoregulation, energetics, and timing of activity in arboreal and semifossorial small mammals.
Dispersal is increasingly recognized as a process of fundamental importance in population dynamics and other aspects of biology. Concurrently, interest in age‐dependent effects on survival, including actuarial senescence, has increased, especially in studies of long‐lived seabirds. Nevertheless, datasets necessary for studying dispersal and age‐dependent effects are few, as these require simultaneous data collection at two or more sites over many years. We conducted a 22‐year capture‐mark‐recapture study of Common Terns Sterna hirundo at three breeding colonies 10–26 km apart in Buzzards Bay, Massachusetts, USA. All birds in the study were of known age (range 2–28 years, median 7 years, n = 3290) and 77% were of known sex. Estimates of adult recapture, survival and breeding dispersal rates were obtained for all age‐classes from 2 to 20 years. The model that acquired 100% of the QAICc (Akaike's Information Criterion adjusted for small sample size and overdispersion) weight in our analysis included age‐specificity in all parameters but no relationship with sex. Our study may be the first to demonstrate age‐specificity in recapture, survival and breeding dispersal rates simultaneously, using a single model. Annual rates of breeding dispersal ranged from <0.01 to 0.27, with a population‐weighted mean of 0.065; they decreased with increasing distance between colony sites and, unexpectedly, increased with age. Breeding dispersal did not increase consistently after years with predation on adults or after an attempt to displace birds from an oiled site. Survival rates did not vary among sites or years. Annual adult survival increased from 0.80 in 2‐year‐old birds to a maximum of approximately 0.88 around age 8 years and then declined to 0.76 at age 20 years, yielding strong evidence for actuarial senescence. The peak annual survival rate of 0.88 is at the low end of other estimates for Common Tern and in the lower part of the range recorded for other terns, but total numbers in the three colonies increased seven‐fold during the study. This was part of a slower increase in the regional population, with net immigration into the study colonies. Our results demonstrate the biological significance of breeding dispersal in local population dynamics and age‐related effects on survival and dispersal from a metapopulation of a long‐lived seabird.
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