Prey switching by stoats (Mustela erminea): a supplemental food experiment

2010 ◽  
Vol 37 (7) ◽  
pp. 604 ◽  
Author(s):  
Des H. V. Smith ◽  
Henrik Moller ◽  
Deborah J. Wilson ◽  
Elaine C. Murphy
Keyword(s):  
Primary Objective ◽  
Food Supplementation ◽  
Alternative Prey ◽  
Prey Switching ◽  
Mustela Erminea ◽  
Supplemental Food ◽  
Impact Experiment ◽  
Frequency Occurrence ◽  
Native Birds ◽  
Grassland Site

Context Prey switching by invasive carnivorans to changing food supply could severely impact on endemic prey of conservation importance, but experimental evidence for prey switching in carnivorans is rare. Stoats (Mustela erminea) were introduced to New Zealand and now threaten survival of many native birds, reptiles and invertebrates. Aim Our primary objective was to see whether abundant food caused stoats inhabiting an alpine grassland site to alter the rate at which they preyed upon weta (Orthoptera : Hemiandrus sp.), hares (Lepus europeus), birds and mice (Mus musculus). Methods We used dead rabbits as supplemental food in a before-after-control-impact experiment. Stoat scats were collected from a treatment and non-treatment site before and following food supplementation. Percentage frequency occurrence of the different prey types was assessed for the two sites during each experimental phase. Conclusions Stoats ate fewer ground weta and hares, the two most abundant prey types, when supplemental food was added. In contrast, consumption of mice remained relatively stable at both sites throughout the experiment, and the consumption of birds declined at both sites. Implications Our experiment suggests that stoats may continue to eat scarce endemic prey at similar per capita rates even when alternative prey are available. However, endemic prey that are locally or regionally abundant may be indirectly impacted by fluctuations in alternative prey.

Effects of Supplemental Food on the Behaviour and Paternity Status of Male Indigo Buntings (Passerina CyaNea)

2018 ◽  
Vol 11 (2) ◽  
pp. 67-73
Author(s):  
Brad T. McLeod ◽  
Gary Ritchison
Keyword(s):  
Time Budget ◽  
Mate Guarding ◽  
Breeding Birds ◽  
Food Supplementation ◽  
Time Budgets ◽  
Blood Samples ◽  
Supplemental Food ◽  
Extra Pair Paternity ◽  
Passerina Cyanea ◽  
And Control

Breeding is energetically costly and, if energy-limited, birds may alter their time budgets, spending less time engaged in some activities and more time in others. Investigators who have provided breeding birds with supplemental food have noted changes in time budgets, but the extent and types of changes have been found to vary among species. Our objective was to determine how food supplementation might influence the time budgets and paternity status of male Indigo Buntings (Passerina cyanea). We studied Indigo Buntings from 8 May to 15 August 2009 in Madison County, Kentucky. Territories of male Indigo Buntings (n=30) were randomly assigned as either food supplemented (n=8) or controls (n=22). During time-budget observations, all behaviours were noted. To determine paternity status, blood samples were collected from adults and nestlings at 16 nests. Males with feeders in their territories spent significantly less time foraging and more time vocalising (chip notes) than males without feeders. Time spent singing and mate guarding by treatment and control males did not differ. Differences in the proportion of extra-pair young did not differ between nests in territories with and without supplemental food. Our results suggest that, when provided with supplemental food, male Indigo Buntings spend less time foraging and more time engaged in other activities. However, neither the presence of supplemental food nor differences in the behaviour of males in food-supplemented versus non-supplemented territories affected rates of extra-pair paternity.

scholarly journals Effects of Supplemental Food on Parental-Care Strategies and Juvenile Survival of Northern Goshawks

The Auk ◽  
2001 ◽  
Vol 118 (2) ◽  
pp. 352-365 ◽  
Author(s):  
Sarah R. Dewey ◽  
Patricia L. Kennedy
Keyword(s):  
Adult Female ◽  
Survival Rates ◽  
Mortality Factor ◽  
Food Supplementation ◽  
Juvenile Survival ◽  
Nest Attendance ◽  
Additional Food ◽  
Supplemental Food ◽  
Risk Of Predation ◽  
Northern Goshawks

Abstract Using food supplementation, we tested whether food limits juvenile survival in a population of Northern Goshawks (Accipiter gentilis) in northeastern Utah. The influence of additional food on female nest attendance also was investigated because those strategies may influence predation mortality rates of juveniles. We provided supplemental food near 13 nests from close to hatching until close to independence during the 1996 and 1997 breeding seasons. Thirteen additional nests served as controls and received no supplemental food. We compared the following variables at treatment and control nests: (1) adult female mass, (2) nestling mass and size, (3) female nest attendance, and (4) juvenile survival. Following supplemental feeding, adult females from treatment nests were heavier than their control counterparts, and remained closer to the nest during the latter part of the nestling period and throughout the postfledging period. Nestlings from supplemented nests were significantly heavier than those from unsupplemented nests, but results for size measurements were equivocal. Survival rates for treatment nestlings were significantly higher than controls in 1997, but not in 1996. Those results support the hypothesis that food does not limit avian reproductive success on an annual basis. Most deaths in 1997 were the result of starvation or sibling competition. That observation, and the fact that fed nestlings were heavier, is consistent with the idea that treatment nestlings were in improved nutritional condition. Overall patterns of mass and nest-attendance for adult female goshawks supports the hypothesis that female condition and behavior are adjusted in response to food supplies. However, it is less clear what role the females' presence in the nest stand plays in mediating juvenile deaths, because we did not document predation as a primary mortality factor during the two years of this study. The apparent flexibility in female nest attendance behavior suggests that such plasticity may be an adaptation to lower the risk of predation.

Food supplementation experiments with terrestrial vertebrates: patterns, problems, and the future

1990 ◽  
Vol 68 (2) ◽  
pp. 203-220 ◽  
Author(s):  
Stan Boutin
Keyword(s):  
Population Level ◽  
Fold Increase ◽  
Food Supplementation ◽  
Home Ranges ◽  
Small Spatial Scale ◽  
Supplemental Food ◽  
Terrestrial Vertebrates ◽  
Tropical Environments ◽  
Body Weights ◽  
Fluctuating Populations

I reviewed 138 cases in which terrestrial vertebrates received supplemental food under field conditions. These cases are strongly biased toward small-bodied herbivores in north temperate environments. Most studies address population level questions and have supplied food over a short term (< 1 year) and on a small spatial scale (to less than 50 individuals). Individuals receiving supplemental food usually had smaller home ranges, higher body weights, and advanced breeding relative to those on control areas. The typical population response to food supplementation was two- to three-fold increase in density, but no change in the pattern of population dynamics. In particular, food addition did not prevent major declines in fluctuating populations. Researchers have failed to examine behaviour of individuals under conditions of supplemental food when addressing questions of population regulation. This review points to the need for researchers to conduct food supplementation experiments in tropical environments, on a larger scale, and over longer periods of time.

Food shortage for breeding Black-billed Magpies (Pica pica): an experiment using supplemental food

1987 ◽  
Vol 65 (5) ◽  
pp. 1270-1274 ◽  
Author(s):  
Wesley M. Hochachka ◽  
David A. Boag
Keyword(s):  
Breeding Population ◽  
Egg Laying ◽  
Food Shortage ◽  
Laying Date ◽  
Food Supplementation ◽  
Natural Food ◽  
Supplemental Feeding ◽  
Pica Pica ◽  
Supplemental Food ◽  
Before And After

Supplemental food was provided to a breeding population of Black-billed Magpies (Pica pica), starting before and after eggs were laid, to determine if and when natural food was limited. The production of fledgling magpies was increased only when supplemental feeding was begun before laying. Laying date was also advanced when supplemental feeding began before laying, but clutch and egg size were not significantly changed. Because the two feeding treatments were conducted in different years, we cannot conclude whether natural food was limiting before or after egg laying. However, out data suggest that the former may have been the case. An improved design for food supplementation experiments, which can be used to determine the time of food shortage, is suggested.

scholarly journals Effect of supplementary food on age ratios of European turtle doves (Streptopelia turtur L.)

2015 ◽  
Vol 38 (1) ◽  
pp. 11-21 ◽  
Author(s):  
G. Rocha ◽  
◽  
P. Quillfeldt ◽  
Keyword(s):  
Breeding Success ◽  
Management Practices ◽  
Management Practice ◽  
Food Supplementation ◽  
Farmland Birds ◽  
Negative Effects ◽  
Supplementary Food ◽  
Supplemental Food ◽  
Age Ratio ◽  
Streptopelia Turtur

Many farmland birds have difficulties finding sufficient food in intensely managed agricultural ecosystems, and in more extensively worked landscapes they are often attracted to human–induced dietary sources. European turtle doves Streptopelia turtur feed on seeds collected on the ground, and are readily attracted to supplementary provided grain at feeding stations. Supplementary feeding is a common management practice on hunting estates around the world. This study was conducted in 40 hunting estates located in central west Spain: 20 sites where supplementary food was provided to attract turtle doves and 20 control sites without feeding stations. At sites with supplemental feeding, the field age ratio was 20% higher and the hunted age ratio was 33% higher than at control sites, indicating a positive effect of the food supplementation of the breeding success around supplemented sites. Both the amount of food provided per day and the amount of time where supplemental food was given (20–120 days) were positively correlated with the field age ratio and, less strongly, with the hunted age ratio. These data suggest that providing extra food can increase the breeding success of this species when the amount provided is sufficiently large and when supplementary food is provided early in the breeding season. However, hunting pressure was also higher at supplemented sites. Future studies should therefore closely monitor the positive and negative effects in order to ascertain which management practices will ensure the viability of these important European turtle dove populations.

scholarly journals Food Limitation During Breeding in a Heterogeneous Landscape

The Auk ◽  
2006 ◽  
Vol 123 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Martin Granbom ◽  
Henrik G. Smith
Keyword(s):  
Spatial Variation ◽  
Breeding Success ◽  
Statistical Power ◽  
Food Limitation ◽  
Agricultural Landscapes ◽  
Food Supplementation ◽  
Breeding Period ◽  
Foraging Habitat ◽  
Growth And Survival ◽  
Supplemental Food

Abstract Breeding success in birds may be determined by the availability of food that parents can provide to growing nestlings. A standard method for testing the occurrence of food limitation is to provide supplemental food during different parts of the breeding period. If there is spatial variation in the strength of food limitation, the effect of such an experiment should also vary spatially. We investigated whether the strength of food limitation during nestling rearing in the European Starling (Sturnus vulgaris) was related to the management intensity of agricultural landscapes. We fed birds mealworms during the nestling period in landscapes with high or low local availability of pasture, the preferred foraging habitat. Both habitat and food supplementation affected growth and survival of nestlings; the effects of the food-supplementation experiment were generally stronger than those of habitat. Mortality mainly struck the last-hatched chick. Both habitat and food supplementation positively affected nestling growth, measured as nestling tarsus length. In addition, food supplementation positively affected feather growth and asymptotic mass. Contrary to expectation, no interactions existed between effects of habitat and food supplementation, which suggests that breeding success was limited by food availability in both landscapes. Potential reasons for this lack of effect are parental compensation and low statistical power. Also, breeding densities were higher in landscapes with more pastures, possibly equalizing the per-capita availability of food. Thus, our results demonstrate that reproductive success was limited by availability of food when local availability of preferred foraging habitat was either low or high, but fail to demonstrate spatial variation in the strength of food limitation. Escasez de Alimentos durante el Período Reproductivo en un Paisaje Heterogéneo

Food supplementation experiments revisited: verifying that supplemental food is used by its intended recipients

2007 ◽  
Vol 85 (6) ◽  
pp. 679-685 ◽  
Author(s):  
A.J. Wirsing ◽  
D.L. Murray
Keyword(s):  
Population Level ◽  
Food Supplementation ◽  
Natural Food ◽  
Supplemental Food ◽  
Snowshoe Hares ◽  
Extra Food ◽  
Study Sites ◽  
Natural Foods ◽  
And Control ◽  
Free Ranging

Field-based food supplementation experiments can determine whether populations are limited by natural food availability. However, they may yield spurious results if added food is hoarded by dominants, exploited by immigrants, or delivered ineffectively. Surprisingly, population-level approaches accounting for these potential sources of bias have not been established. We explored responses of free-ranging snowshoe hares ( Lepus americanus Erxleben, 1777) to food supplementation by contrasting per capita browsing rates on three study sites with added food with those on three control sites during two winters. Food augmentation reduced foraging pressure by hares; this reduction was significant when browse species of high dietary importance were considered. By implication, hares on manipulated sites switched from favored natural foods to supplemental food, meaning that the extra food found its mark and was not heavily exploited by immigrants or hoarded by dominants. Demographic responses to food addition were not detected on the manipulated sites, indicating that the study population was not food limited. Given the success with which we detected the signal of supplementation and eliminated potential confounding factors, we suggest that future studies using food addition in the context of herbivore population dynamics would benefit from a more mechanistic approach; this may involve measurement of browsing rates on manipulated and control sites.

Food availability in spring influences reproductive output in the seed-preying edible dormouse (Glis glis)

2009 ◽  
Vol 87 (7) ◽  
pp. 555-565 ◽  
Author(s):  
T. Kager ◽  
J. Fietz
Keyword(s):  
Litter Size ◽  
Food Availability ◽  
Reproductive Output ◽  
European Beech ◽  
Food Supplementation ◽  
Lactation Period ◽  
Glis Glis ◽  
Supplemental Food ◽  
Fagus Sylvatica L ◽  
Edible Dormice

Edible dormice ( Glis glis (L., 1766)) display strong annual variation in their reproductive output that is closely related to resource availability, commonly measured through the quantity of seeds produced by their most important food provider, the European beech ( Fagus sylvatica L.). Dormouse mating takes place several weeks before beech seeds ripen, and to the present day it remains unclear how dormice achieve optimized reproductive output in reflection of the quantity of food available in the future. The first aim of this field study carried out over 13 years was thus to investigate the relationship between beech masting and reproductive performance in edible dormice in Germany. If food availability in spring influenced litter size, this would partially explain observed natural variability in offspring numbers. We thus chose an experimental approach and provided supplemental food to edible dormice in the field. Our results showed that numbers and proportions of reproductively active females, as well as litter sizes, between 1993 and 2005 were positively correlated with beech mast. Food supplementation positively affected litter size and litters of food-supplemented females were found to be larger than those of unsupplemented females. Food-supplemented mothers and their offspring gained body mass considerably faster during lactation and were heavier at the end of the lactation period compared with controls. However, juvenile body size, as well as its increase, did not differ between the two treatments. Our results suggest a link between edible dormice reproductive output and food availability after emergence from hibernation.

Does predation risk cause snowshoe hares to modify their diets?

2003 ◽  
Vol 81 (12) ◽  
pp. 1973-1985 ◽  
Author(s):  
K E Hodges ◽  
A R.E Sinclair
Keyword(s):  
Species Composition ◽  
Predation Risk ◽  
Sublethal Effects ◽  
Population Cycle ◽  
Food Supplementation ◽  
Snowshoe Hare ◽  
Supplemental Food ◽  
Snowshoe Hares ◽  
Wide Range ◽  
Mammalian Predators

Snowshoe hares (Lepus americanus) undergo a 10-year population cycle with several years of low densities. Several authors have suggested that snowshoe hares modify their foraging behaviour to reduce predation risk during the low phase, resulting in protein-poor diets and poor body condition. We test that idea by using a factorial manipulation of food supplementation and predator reduction and by examining the species composition, browse size, and nutritional quality of snowshoe hare diets during 3 years of low snowshoe hare abundance in southwestern Yukon. Our results negate the hypothesis that snowshoe hares change their diets in response to mammalian predators during the cyclic low phase. Snowshoe hares on the different treatments had diets that differed in species composition and twig sizes, but protected hares did not have higher protein diets than unprotected hares. Snowshoe hares with access to supplemental food ate more fibrous and lower protein natural browse than unfed hares, showing that they did not choose diets primarily for protein content. Instead, snowshoe hares converted a wide range of forage availabilities into similar intakes of protein and fibre, despite variation in predator presence. Our results suggest that snowshoe hares select their diets to balance the protein and fibre contents. Although sublethal effects of predators may influence cyclic dynamics, our results show that such a feedback does not occur via a nutritional mechanism, counter to previous suggestions.

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