Population Crash

2021 ◽  
pp. 3880-3880
Keyword(s):  
2014 ◽  
Vol 92 (2) ◽  
pp. 97-104 ◽  
Author(s):  
D. Bauer ◽  
M. Schiess-Meier ◽  
D.R. Mills ◽  
M. Gusset

In many African countries, large carnivores such as lions (Panthera leo (L., 1758)) are under serious threat through conflict with people, declining prey abundance, and exposure to disease. Spoor and prey count surveys were used to determine temporal and spatial variation in lion density in Khutse Game Reserve (KGR), Botswana, and the adjacent communal grazing area. Estimated lion density in KGR for the period September 2008 – June 2010 was 41% lower than for the period June 2007 – August 2008 (1.02 vs. 1.72 lions/100 km2). Prior to this population crash in mid-2008, estimated lion density in the communal grazing area (1.21 lions/100 km2) was 30% lower than inside KGR. The relative abundance of the three most abundant, preferred prey species of lions occurring in KGR decreased from 2001 to 2008 by 50%–79%. Based on two prey biomass estimates, the lion population in KGR was below the potential carrying capacity of the habitat after the crash in mid-2008. These results suggest that there could be a human-caused population sink around KGR, which might be strong enough to threaten the long-term survival of lions in the area; particularly if this edge effect is intensified by prey depletion and disease outbreaks, which might have caused the sudden decline in the lion population.


2020 ◽  
Vol 80 ◽  
pp. 177-191
Author(s):  
Joseph R. Coelho ◽  
Jon M. Hastings ◽  
Charles W. Holliday

Factors affecting the ecology of a large population of Pacific cicada killers (Sphecius convallis) occupying a field of mine tailings in Ruby, AZ, were examined. Burrows were quite dense in certain areas around the periphery of the mine tailings, but were dispersed randomly within these areas. Approximately 1600 females (based on burrow counts) and 2500 males (based on mark-recapture) were recorded, yielding a total population estimate of 5000–6000 adults. Female wasps were able to dig much more rapidly in the mine tailings than their congeners S. speciosus in soils from PA, suggesting that the habitat suitability was a large factor in this robust population. Provisioning rate was comparatively slow, however, suggesting that cicada abundance in that year was not a contributor to the high population density. The presence of a sap-producing tree may have eased the energetic and thermoregulatory demands of the wasps. Although excavations revealed that the number of burrows and cells could easily maintain the population size, the lack of cicadas probably resulted instead in a population crash the following season.


Mammal Study ◽  
2021 ◽  
Vol 46 (1) ◽  
Author(s):  
Kazutaka M. Takeshita ◽  
Mugino O. Kubo ◽  
Mayumi Ueno ◽  
Mari Ishizaki ◽  
Hiroshi Takahashi ◽  
...  

10.2307/5651 ◽  
1995 ◽  
Vol 64 (4) ◽  
pp. 481 ◽  
Author(s):  
A.W. Illius ◽  
S.D. Albon ◽  
J.M. Pemberton ◽  
I.J. Gordon ◽  
T.H. Clutton-Brock

2019 ◽  
Vol 29 (13) ◽  
pp. R627-R630
Author(s):  
Samuel K. Wasser ◽  
Kathleen S. Gobush
Keyword(s):  

Koedoe ◽  
1991 ◽  
Vol 34 (1) ◽  
Author(s):  
D. Buys ◽  
H.M. Dott

The history of an eland population on the S A Lombard Nature Reserve in the western Transvaal is described. From a founder population of four eland in 1950 and 1951, the population grew to about 35 animals and was kept at this level through culling and translocation until 1976. During 1976 and 1977 unusual heavy rains were experienced and culling and removals were temporarily suspended. As a result the population increased unchecked and reached a peak of 81 in 1981. When climatic conditions returned to normal this was followed by a population crash in which 66 eland died over a period of three years. Calves are born throughout the year, but the majority of births occur during the period October to December, with a peak in November. The females have a high calving rate (90,9 ) and calf mortality is low (16,7 ).


Parasitology ◽  
1992 ◽  
Vol 105 (3) ◽  
pp. 481-492 ◽  
Author(s):  
F. M. D. Gulland ◽  
M. Fox

SUMMARYThe epidemiology of nematode infections of Soay sheep on the island of St Kilda over a period of 2 years (August 1988–August 1990) spanning a host population crash is described. Infective larvae (L3) levels on pasture were high (2422±365 L3/kg D.M. grass in midsummer 1988) when host population density was high, decreasing after the sheep population declined by 70% in early 1989 (601 ±14 L3/kg D.M. in midsummer 1989). The availability of infective larvae to sheep increased during the winter of 1988–1989, probably as a result of concentration of existing larvae on grass as vegetation was destroyed by bad weather and overgrazing. Increased availability of pre-parasitic stages was accompanied by a marked increased in faecal egg counts from sheep of all ages and both sexes. Prevalence and intensity of infection (faecal egg counts) were higher in males than females throughout the 2-year study (χ2 = 208.3, P < 0.005 and F1.2000 = 304, P < 0.001 respectively), except during the lambing periods, and decreased with age in both sexes. Changes in prevalence and intensity of strongyle infections were associated with changes in host population density. Prevalence and intensity of Dictyocaulus filaria larvae in faeces increased during the host population crash. Infection intensity decreased with age (F1.203 = 44.02, P < 0.001) and was higher in males than females (F1.203 = 13.45, P < 0.001).


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