scholarly journals Assessing the Effects of Introduced Norway Rats (Rattus Norvegicus) on Survival and Productivity of Least Auklets (Aethia Pusilla)

The Auk ◽  
2006 ◽  
Vol 123 (3) ◽  
pp. 681-694 ◽  
Author(s):  
Heather L. Major ◽  
Ian L. Jones ◽  
G. Vernon Byrd ◽  
Jeffrey C. Williams
Keyword(s):  
Growth Rates ◽  
Rattus Norvegicus ◽  
Prey Availability ◽  
Survival Rates ◽  
Adult Survival ◽  
Chick Growth ◽  
Aethia Pusilla ◽  
Cast Doubt ◽  
Fledging Mass ◽  
Norway Rats

Abstract We assessed potential effects of introduced Norway rats (Rattus norvegicus) on Least Auklets (Aethia pusilla) breeding at Sirius Point on Kiska Island, the largest auklet colony in the Aleutian Islands, Alaska. We compared productivity, chick growth, and adult survival of Least Auklets during 2001-2003 at Kiska and two nearby, rat-free Least Auklet colonies on Buldir and Kasatochi islands. During 2001 and 2002 (when rats were abundant), productivity at Kiska was the lowest ever recorded for this species (0.09–0.16 chicks fledged per eggs laid), primarily because of high mortality of newly hatched chicks. Growth rates and mean fledging mass were both lower on Kiska than on rat-free islands, though there were some interannual differences in these patterns. Adult survival rates were highly variable among years but strongly concordant among colonies, and survival from 2001 to 2002 on Kiska (0.881 ± 0.033) did not differ significantly from long-term averages on either Buldir (0.853 ± 0.014, 1990-2003) or Kasatochi (0.893 ± 0.027, 1996-2003) islands. Although we found little evidence at nesting crevices of predation on adults, eggs, or chicks, low productivity and slow chick growth were both consistent with disturbance caused by rats, particularly through disruption of adults attempting to brood or provision young chicks. Breeding failure may have been exacerbated by low prey availability for chick provisioning, but the lack of concordance in either productivity or chick growth rates between Kiska Island and nearby rat-free Buldir Island cast doubt on this possibility. Évaluer les Effets de Rattus norvegicus Introduits sur la Survie et la Productivité de Aethia pusilla

ASSESSING THE EFFECTS OF INTRODUCED NORWAY RATS (RATTUS NORVEGICUS) ON SURVIVAL AND PRODUCTIVITY OF LEAST AUKLETS (AETHIA PUSILLA)

The Auk ◽  
2006 ◽  
Vol 123 (3) ◽  
pp. 681 ◽  
Author(s):  
Heather L. Major ◽  
Ian L. Jones ◽  
G. Vernon Byrd ◽  
Jeffrey C. Williams
Keyword(s):  
Rattus Norvegicus ◽  
Aethia Pusilla ◽  
Norway Rats

Life in the Slow Lane: Ecology and Conservation of Long-Lived Marine Animals

1999 ◽  
Keyword(s):  
Life History ◽  
Population Growth ◽  
Growth Rates ◽  
Anthropogenic Impacts ◽  
Survival Rates ◽  
Conservation Strategies ◽  
Adult Survival ◽  
Population Growth Rates ◽  
Important Prey ◽  
The Status

<em>Abstract.</em> —Seabirds become mature at a late age, experience low annual fecundity, often refrain from breeding, and enjoy annual adult survival rates as high as 98%. This suite of life history characteristics limits the capacity for seabird populations to recover quickly from major perturbations, and presents important conservation challenges. Concern over anthropogenic impacts on seabird populations has led to the initiation of long-term field programs to monitor seabird reproductive performance and population dynamics. In addition, seabirds have been recognized as potentially useful and economical indicators of the state of the marine environment and, in particular, the status of commercially important prey stocks. This paper reviews demographic and life history attributes of seabird populations and uses this information to explore the consequences of longevity from the respective standpoints of conservation and monitoring goals. Analysis of a simplified life cycle model reveals that maximum potential population growth rates (λ) under ideal circumstances fall within the range of 1.03–1.12 for most species, though growth rates realized in nature will always be lower. Elasticity analysis confirms that seabird population growth rates are extremely sensitive to small variations in adult survival rates, and dictates that survival monitoring should be considered an essential component of conservation strategies. As in other organisms with long life spans, ecological and physiological costs of reproduction are expected to figure prominently in seabird reproductive decisions. Consequently, understanding how seabirds allocate reproductive effort in response to varying environmental conditions is an important prerequisite for correctly interpreting field data from monitoring studies.

Distribution, biology and prey selection of the introduced Norway Rat Rattus norvegicus at Kiska Island, Aleutian Islands, Alaska

2005 ◽  
Vol 11 (2) ◽  
pp. 105 ◽  
Author(s):  
Heather L. Major ◽  
Ian L. Jones
Keyword(s):  
Rattus Norvegicus ◽  
Size Structure ◽  
Negative Impact ◽  
Prey Selection ◽  
Adult Rats ◽  
Norway Rat ◽  
Aethia Pusilla ◽  
Reproductive Females ◽  
Norway Rats ◽  
Selection Of

At Kiska Island, Alaska, USA we quantified age, sex, size, distribution and predation of Least Auklets Aethia pusilla by non-indigenous Norway Rats Rattus norvegicus, to evaluate their impact on auklet reproductive success. Rat distribution was assessed by surveying accessible parts of Kiska Island for rat sign and prey hoards. To quantify prey selection and infer diet, the contents of all hoards found were identified. Age, sex and size structure of the rat population was assessed using limited snap trapping on and off the Sirius Point auklet colony. Norway Rat sign was abundant in all areas near breeding seabirds and marine sources of food but rat sign abundance varied among years at Sirius Point. Although we found a larger proportion of juvenile to adult rats (0.54 : 0.46, p < 0.01) at Sirius Point, no significant differences were found in the proportion of reproductive to non-reproductive females (0.50 : 0.27, p > 0.05) or in overall adult body size (257 g and 37 cm : 236 g and 35 cm, p > 0.05) between Sirius Point and Christine Lake where breeding auklets are absent. Surplus killing and food hoarding by rats was noted in all years during the auklet laying period, with adult Least Auklets being the principal prey taken (4-148 individuals per hoard, n = 16 hoards). Our observations were consistent with the notion that rats have a negative impact on auklet populations, but for management purposes further information on whether rats are the sole cause of auklet reproductive failure is required.

Persistence of giants: population dynamics of the limpet Scutellastra laticostata on rocky shores in Western Australia

2020 ◽  
Vol 646 ◽  
pp. 79-92
Author(s):  
RE Scheibling ◽  
R Black
Keyword(s):  
Population Dynamics ◽  
Western Australia ◽  
Size Structure ◽  
Survival Rates ◽  
Maximum Size ◽  
High Rate ◽  
Adult Survival ◽  
Rocky Shores ◽  
Adult Size ◽  
Decadal Time Scale

Population dynamics and life history traits of the ‘giant’ limpet Scutellastra laticostata on intertidal limestone platforms at Rottnest Island, Western Australia, were recorded by interannual (January/February) monitoring of limpet density and size structure, and relocation of marked individuals, at 3 locations over periods of 13-16 yr between 1993 and 2020. Limpet densities ranged from 4 to 9 ind. m-2 on wave-swept seaward margins of platforms at 2 locations and on a rocky notch at the landward margin of the platform at a third. Juvenile recruits (25-55 mm shell length) were present each year, usually at low densities (<1 m-2), but localized pulses of recruitment occurred in some years. Annual survival rates of marked limpets varied among sites and cohorts, ranging from 0.42 yr-1 at the notch to 0.79 and 0.87 yr-1 on the platforms. A mass mortality of limpets on the platforms occurred in 2003, likely mediated by thermal stress during daytime low tides, coincident with high air temperatures and calm seas. Juveniles grew rapidly to adult size within 2 yr. Asymptotic size (L∞, von Bertalanffy growth model) ranged from 89 to 97 mm, and maximum size from 100 to 113 mm, on platforms. Growth rate and maximum size were lower on the notch. Our empirical observations and simulation models suggest that these populations are relatively stable on a decadal time scale. The frequency and magnitude of recruitment pulses and high rate of adult survival provide considerable inertia, enabling persistence of these populations in the face of sporadic climatic extremes.

scholarly journals Warming Arctic summers unlikely to increase productivity of shorebirds through renesting

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sarah T. Saalfeld ◽  
Brooke L. Hill ◽  
Christine M. Hunter ◽  
Charles J. Frost ◽  
Richard B. Lanctot
Keyword(s):  
Climate Change ◽  
Survival Rates ◽  
The Arctic ◽  
Adult Survival ◽  
Chick Survival ◽  
Ecological Processes ◽  
Bird Populations ◽  
Phenological Mismatch ◽  
Daily Survival ◽  
Adequate Food

AbstractClimate change in the Arctic is leading to earlier summers, creating a phenological mismatch between the hatching of insectivorous birds and the availability of their invertebrate prey. While phenological mismatch would presumably lower the survival of chicks, climate change is also leading to longer, warmer summers that may increase the annual productivity of birds by allowing adults to lay nests over a longer period of time, replace more nests that fail, and provide physiological relief to chicks (i.e., warmer temperatures that reduce thermoregulatory costs). However, there is little information on how these competing ecological processes will ultimately impact the demography of bird populations. In 2008 and 2009, we investigated the survival of chicks from initial and experimentally-induced replacement nests of arcticola Dunlin (Calidris alpina) breeding near Utqiaġvik, Alaska. We monitored survival of 66 broods from 41 initial and 25 replacement nests. Based on the average hatch date of each group, chick survival (up to age 15 days) from replacement nests (Ŝi = 0.10; 95% CI = 0.02–0.22) was substantially lower than initial nests (Ŝi = 0.67; 95% CI = 0.48–0.81). Daily survival rates were greater for older chicks, chicks from earlier-laid clutches, and during periods of greater invertebrate availability. As temperature was less important to daily survival rates of shorebird chicks than invertebrate availability, our results indicate that any physiological relief experienced by chicks will likely be overshadowed by the need for adequate food. Furthermore, the processes creating a phenological mismatch between hatching of shorebird young and invertebrate emergence ensures that warmer, longer breeding seasons will not translate into abundant food throughout the longer summers. Thus, despite having a greater opportunity to nest later (and potentially replace nests), young from these late-hatching broods will likely not have sufficient food to survive. Collectively, these results indicate that warmer, longer summers in the Arctic are unlikely to increase annual recruitment rates, and thus unable to compensate for low adult survival, which is typically limited by factors away from the Arctic-breeding grounds.

scholarly journals Field trials of flocoumafen against warfarin-resistant infestations of the Norway rat (Rattus norvegicus Berk)

1986 ◽  
Vol 96 (3) ◽  
pp. 467-473 ◽  
Author(s):  
A. P. Buckle
Keyword(s):  
Rattus Norvegicus ◽  
Field Trials ◽  
Anticoagulant Rodenticide ◽  
Complete Control ◽  
Norway Rat ◽  
Norway Rats ◽  
Farm Buildings

SUMMARYThe anticoagulant rodenticide flocoumafen was tested against warfarin-resistant Norway rats (Rattus norvegicus Berk.) infesting farm buildings. Complete control was obtained in 10–21 days (mean 14·2 days) in six treatments in which baits poisoned with 0·005% flocoumafen were maintained, in surplus, until rats ceased to feed from them. A further six treatments, in which the application of poisoned bait was restricted to periodic placements of 50 g, were also completely successful in 15–30 days (mean 21·0 days). Less poisoned bait was used in the restricted flocoumafen treatments than in the unrestricted treatments but the time taken to control the rat infestations was significantly longer.

scholarly journals Fitness of breeders in social Damaraland mole-rats is independent of group size

2021 ◽  
Author(s):  
Jack Thorley ◽  
Hanna Bensch ◽  
Kyle Finn ◽  
Tim Clutton-Brock ◽  
Markus Zöttl
Keyword(s):  
Reproductive Success ◽  
Group Size ◽  
Survival Rates ◽  
Group Living ◽  
Adult Survival ◽  
High Survival ◽  
Successful Reproduction ◽  
Related Group ◽  
Group Members ◽  
Using Data

Damaraland mole-rats (Fukomys damarensis) are usually viewed as an obligatorily group living eusocial species in which successful reproduction is dependent on reproductive altruism of closely related group members. However, the reproductive ecology of social mole-rats in their natural environment remains poorly understood and it is unclear to what extent successful reproduction is dependent on assistance from other group members. Using data from a 7-year field study of marked individuals, we show that, after dispersal from their natal group, individuals typically settled alone in new burrow systems where they enjoyed high survival rates, and often remained in good body condition for several years before finding a mate. Unlike most other eusocial or singular cooperative breeders, we found that Damaraland mole-rats reproduced successfully in pairs without helpers and experimentally formed pairs had the same reproductive success as larger established groups. Overall there was only a weak increase in reproductive success with increasing group size and no effect of group size on adult survival rates across the population. Juveniles in large groups grew faster early in life but their growth rates declined subsequently so that they eventually plateaued at a lower maximum body mass than juveniles from small groups. Taken together, our data suggest that the fitness benefits of group living to breeders are small and we suggest that extended philopatry in Damaraland mole-rats has evolved because of the high costs and constraints of dispersal rather than because of strong indirect benefits accrued through cooperative behaviour.

The production characteristics of the indigenous Imroz and Kivircik sheep breeds in Turkey

2004 ◽  
Vol 34 ◽  
pp. 57-66 ◽  
Author(s):  
A. Yilmaz ◽  
M. Ozcan ◽  
B. Ekiz ◽  
A. Ceyhan ◽  
A. Altine
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Milk Production ◽  
Growth Rates ◽  
Survival Rates ◽  
Growth Characteristics ◽  
Marmara Region ◽  
Sheep Breeds ◽  
Survival And Growth ◽  
Production Characteristics

SummaryThis study was carried out to investigate the fertility, milk production and body weight of ewes and the survival and growth characteristics of lambs of the indigenous Imroz and Kivircik sheep breeds. The Imroz and Kivircik sheep breeds are included among the genetic resources in the project for the conservation of the indigenous breeds in Turkey.Conception rates for Imroz and Kivircik ewes were 57.6% and 81.7% respectively, litter sizes were 1.2 and 1.2 respectively, milk yields were 89 kg and 62 kg respectively and average live weights (2–7 years of age) were 43 kg and 55 kg, respectively. Imroz and Kivircik lambs had survival rates at weaning (90th day) of 98% and 96%, birth weights of 3.3 kg and 4.1 kg and weaning weights of 19.8 kg and 28.0 kg, respectively.The results showed that the Kivircik sheep were heavier and the lambs had a better growth rate until weaning than the Imroz breed. However, the milk production of the Imroz ewes was higher than that of Kivircik. The lambs of both breeds had a satisfactory survival and growth rates until weaning and these results might be regarded as a desired adaptation of the Imroz and Kivircik lambs to the environmental conditions of the Marmara Region.

Effect of Prey Density and Prey Size on Growth and Survival of Juvenile Walleye (Stizostedion vitreum vitreum)

1989 ◽  
Vol 46 (8) ◽  
pp. 1323-1328 ◽  
Author(s):  
Michael G. Fox
Keyword(s):  
Prey Density ◽  
Prey Availability ◽  
Food Limitation ◽  
Survival Rates ◽  
Stizostedion Vitreum ◽  
Growth And Survival ◽  
First Feeding ◽  
Length Increase ◽  
Prey Length ◽  
Chironomid Biomass

I investigated the influence of food availability on growth and survival of walleye (Stizostedion vitreum vitreum) fry stocked in six fertilized experimental ponds (density 40 fish∙m−3) and reared for 8 wk. Walleye fed largely on chironomid larvae and cyclopoid copepods in weeks 1 and 2, and chironomids thereafter. Prey choice and consumption were strongly influenced by chironomid biomass in the benthos, and to a lesser extent by zoo-plankton density. Weekly length increase of the populations and mean length in week 7 were significantly correlated with chironomid benthic biomass and mean prey length. Chironomid biomass and density of large zoo-plankton together explained 56% of the variation in the weekly population growth rate. Despite obvious food limitation in the second half of the experiment, pond survival rate was not significantly correlated with mean prey density, mean stomach fullness, or percentage of fish with empty stomachs. The results indicate that juvenile walleye growth can be regulated by the density and size of available prey. Prey availability apparently does not regulate short term juvenile walleye survival rates after the period around first feeding.

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