Density Dependent Food Limitation and Maximal Production in Wild Reindeer Herds

1986 ◽  
Vol 50 (2) ◽  
pp. 314 ◽  
Author(s):  
Terje Skogland
Keyword(s):  
Food Limitation ◽  
Density Dependent ◽  
Maximal Production ◽  
Wild Reindeer

Temporal changes in molar wear rate of a sika deer population under density-dependent food limitation

2015 ◽  
Vol 297 (2) ◽  
pp. 139-145 ◽  
Author(s):  
K. Takeshita ◽  
M. Ishizaki ◽  
R. Mitsuya ◽  
H. Takahashi ◽  
T. Yoshida ◽  
...  
Keyword(s):  
Wear Rate ◽  
Sika Deer ◽  
Food Limitation ◽  
Temporal Changes ◽  
Density Dependent ◽  
Deer Population

scholarly journals Population regulation of African buffalo in the Mara–Serengeti ecosystem

2015 ◽  
Vol 42 (5) ◽  
pp. 382 ◽  
Author(s):  
Holly T. Dublin ◽  
Joseph O. Ogutu
Keyword(s):  
Land Use ◽  
Population Dynamics ◽  
Population Growth ◽  
Density Dependence ◽  
Food Limitation ◽  
Land Use Changes ◽  
African Buffalo ◽  
Regulatory Factor ◽  
Density Dependent ◽  
Serengeti Ecosystem

Context The processes regulating ungulate populations have been the focus of numerous studies. For the African buffalo (Syncerus caffer Sparrman) population inhabiting the Mara–Serengeti ecosystem, rinderpest was the primary regulatory factor up to the mid-1960s. Following reduction of rinderpest and buffalo population increase, interspecific competition for food, notably with cattle and wildebeest (Connochaetes taurinus Burchell), was thought to be the primary regulatory factor in the ecosystem. Aims We analysed buffalo population trends and the relationship between buffalo population growth and rainfall and density dependence in the Mara–Serengeti ecosystem and discuss the findings in the context of the key ecosystem processes governing buffalo population dynamics in African savannas, namely, food limitation, competition, predation, disease and land use changes. Methods We analysed buffalo population dynamics in the Mara–Serengeti ecosystem in relation to rainfall and density dependence feedback between 1984 and 2010. Key results Buffalo population growth was both significantly density-dependent and positively correlated with the dry season rainfall after, but not before, a severe drought in 1993. Buffalo numbers crashed by 48.6% in 1984–85 and by 76.1% in 1993–94 during severe droughts when food availability was lowest and competition with the more numerous cattle and wildebeest was highest. Conclusions Recovery of buffalo numbers to pre-drought levels took 8–9 years after the 1984–85 drought but was much slower, with buffaloes numbering merely 36% of their 1993 population (12 895 animals) 18 years after the 1993–94 drought despite intermittent periods of high rainfall, probably due to demographic and/or reproductive factors, heightened competition with livestock, land use changes in the adjoining pastoral ranches, lion predation and recurrent severe droughts. Implications Our findings demonstrate how food limitation caused by droughts associated with the hemispheric El Niño–Southern Oscillation can cause severe declines in and threaten the persistence of large ungulate populations. The findings also portray how density-dependent food limitation, competition, predation, land use changes and other factors can accentuate the effect of droughts and greatly prolong population recovery.

Analysis of an estuarine striped bass (Morone saxatilis) population: influence of density-dependent mortality between metamorphosis and recruitment

2000 ◽  
Vol 57 (2) ◽  
pp. 478-486 ◽  
Author(s):  
W J Kimmerer ◽  
J H Cowan, Jr. ◽  
L W Miller ◽  
K A Rose
Keyword(s):  
San Francisco ◽  
Striped Bass ◽  
Carrying Capacity ◽  
Food Limitation ◽  
Morone Saxatilis ◽  
Fish Stock ◽  
Compensatory Mechanism ◽  
Density Dependent ◽  
Density Dependent Mortality ◽  
Dependent Mortality

Compensation due to density-dependent mechanisms is essential for the maintenance of an exploited fish stock. Understanding compensation is important for understanding population regulation and responses to added mortality. We examined possible density-dependent effects on striped bass (Morone saxatilis) in the San Francisco Estuary. Three sets of data from sampling programs for young striped bass showed density-dependent mortality between 1 month of age and 8-12 months. The relationships between two indices of young striped bass abundance and recruitment at age 3 fit a Beverton-Holt function, also indicating density dependence. The carrying capacity, as determined by the asymptote of the Beverton-Holt curves, has declined over the last two to three decades. These results are consistent with a compensatory mechanism based on food limitation occurring after metamorphosis and with the decline in food resources observed in the estuary over the same period. The decline in striped bass over the last two to three decades may be partly due to this declining carrying capacity.

Density Dependence of Larval Growth of a Marine Fish, the Southern Bluefin Tuna, Thunnus maccoyii

1991 ◽  
Vol 48 (8) ◽  
pp. 1358-1363 ◽  
Author(s):  
Greg P. Jenkins ◽  
Jock W. Young ◽  
Tim L. O. Davis
Keyword(s):  
Growth Rate ◽  
Marine Fish ◽  
Food Limitation ◽  
Larval Growth ◽  
Bluefin Tuna ◽  
Density Dependent ◽  
East Indian ◽  
Southern Bluefin Tuna ◽  
Slow Growing ◽  
East Indian Ocean

Competition for food among larvae and subsequent reduction in growth rates has been proposed as a mechanism to explain the apparent density-dependent control of some exploited marine fish populations, but has received little support from field data. Growth of larvae of southern bluefin tuna, Thunnus maccoyii, in the East Indian Ocean was significantly different among stations sampled randomly within a 20-km radius. Growth rate was positively correlated with feeding rate but not with temperature, indicating that larvae were food limited to a varying degree. A negative correlation between growth rate and abundance suggested that food limitation was density dependent. Regression analysis indicated that in areas of highest larval densities there was an approximate 25% reduction in growth rate. We suggest that in areas of high abundance, larvae were competing for food, leading to a density-dependent reduction of growth rate. Because the larval stage of high mortality is prolonged, cumulative mortality of slow-growing larvae over this period may be greater, even if the mortality rate is constant.

Density mediates grasshopper performance in response to temperature manipulation and spider predation in tallgrass prairie

2016 ◽  
Vol 107 (2) ◽  
pp. 261-267 ◽  
Author(s):  
A.N. Laws ◽  
A. Joern
Keyword(s):  
Tallgrass Prairie ◽  
Food Chain ◽  
Species Interactions ◽  
Abiotic Factors ◽  
Food Limitation ◽  
Wolf Spider ◽  
Density Dependent ◽  
Biotic And Abiotic Factors ◽  
Context Dependent ◽  
Response To Temperature

AbstractSpecies interactions are often context-dependent, where outcomes require an understanding of influences among multiple biotic and abiotic factors. However, it remains unclear how abiotic factors such as temperature combine with important biotic factors such as density-dependent food limitation and predation to influence species interactions. Using a native grassland – grasshopper – wolf spider model food chain in tallgrass prairie, we conducted a manipulative field experiment to examine how predator–prey interactions respond to manipulations of temperature, grasshopper density, and food chain length. We find that grasshopper performance responses to temperature and predator treatments were density dependent. At high densities, grasshopper survival decreased with increased temperature when no spiders were present. When spiders were present, grasshopper survival was reduced, and this effect was strongest in the cooled treatment. In contrast, grasshopper survival did not vary significantly with spider presence or among temperature treatments at low grasshopper densities. Our results indicate that context-dependent species interactions are common and highlight the importance of understanding how and when key biotic and abiotic factors combine to influence species interactions.

scholarly journals Density-dependent increase in superpredation linked to food limitation in a recovering population of northern goshawks Accipiter gentilis

2017 ◽  
Vol 48 (9) ◽  
pp. 1205-1215 ◽  
Author(s):  
S. R. Hoy ◽  
S. J. Petty ◽  
A. Millon ◽  
D. P. Whitfield ◽  
M. Marquiss ◽  
...  
Keyword(s):  
Food Limitation ◽  
Accipiter Gentilis ◽  
Density Dependent ◽  
Northern Goshawks
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