Annual variation in breeding success and changes in population density of Cacajao calvus ucayalii in the Lago Preto Conservation Concession, Peru

2013 ◽  
pp. 173-178 ◽  
Author(s):  
M. Bowler ◽  
C. Barton ◽  
S. McCann-Wood ◽  
P. Puertas ◽  
R. Bodmer
Keyword(s):  
Population Density ◽  
Breeding Success ◽  
Annual Variation

Human influences on breeding of south polar skuas in the eastern Larsemann Hills, Princess Elizabeth Land, East Antarctica

Polar Record ◽  
1996 ◽  
Vol 32 (180) ◽  
pp. 43-50 ◽  
Author(s):  
Z. Wang ◽  
F.I. Norman ◽  
J.S. Burgess ◽  
S.J. Ward ◽  
A.P. Spate ◽  
...  
Keyword(s):  
Breeding Success ◽  
Human Activities ◽  
Annual Variation ◽  
East Antarctica ◽  
Larsemann Hills ◽  
Catharacta Maccormicki ◽  
Area Development ◽  
South Polar ◽  
Made In ◽  
Area Data

AbstractBreeding activity of pairs of south polar skuas (Catharacta maccormicki) in the eastern Larsemann Hills, Princess Elizabeth Land, East Antarctica, was recorded in five of six austral summers between 1988 and 1994. More detailed observations of breeding success were made in the 1989/90 and 1993/94 summers. Although relatively few skuas nest in the study area, data suggest that there was inter-annual variation in numbers and locations of territories and chicks fledged. This variation is discussed in relation to increased human activities in the area (development of a summer base and more permanent stations) and to an enhanced access to human-derived foods. It is concluded that there has been some human impact on this species in the Larsemann Hills.

Annual variation in laying date and breeding success of Brown Noddies on Aride Island, Seychelles

2006 ◽  
Vol 106 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Jaime A. Ramos ◽  
Anna Maria Maul ◽  
John Bowler ◽  
Louisa Wood ◽  
Rob Threadgold ◽  
...  
Keyword(s):  
Breeding Success ◽  
Annual Variation ◽  
Laying Date

Breeding Biology, Diet and Morphometrics of the King Shag, Phalacrocorax Albiventer Purpurascens, at Macquarie Island.

1985 ◽  
Vol 12 (1) ◽  
pp. 81 ◽  
Author(s):  
NP Brothers
Keyword(s):  
Clutch Size ◽  
Breeding Success ◽  
Annual Variation ◽  
Total Population ◽  
Nest Site ◽  
Pair Bond ◽  
Benthic Fish ◽  
Macquarie Island ◽  
Minimum Age ◽  
Age At First Breeding

Nineteen colonies of the king shag, Phalacrocorax albiventer purpurascens, occur on Macquarie I. varying in size from 3 to 320 breeding pairs. The total population was estimated at 660 breeding pairs in 1975-79. Breeding varied annually, but most eggs were laid in the last half of October with an average clutch size over two seasons of 2.7 eggs. Most chicks hatched by late December and fledged from late January onwards. Minimum age at first breeding was 2 years but most shags did not breed until the age of 4 years or more. Faithful breeding pairs tended to be more successful than those that changed mates although most remained together for only one or two seasons. Male shags had a stronger tendency to retain their nest-site than did females, and it was the female that was responsible for the breakdown of the pair-bond. This breakdown and annual variation in breeding success was thought to be mainly due to shortage of food, which consisted solely of benthic fish.

scholarly journals Smålommens Gavia stellata häckningsframgång i artens svenska kärnområde

Ornis Svecica ◽  
2002 ◽  
Vol 12 (1–2) ◽  
pp. 1-33
Author(s):  
Börje Dahlén ◽  
Mats O G Eriksson
Keyword(s):  
Breeding Success ◽  
Large Scale ◽  
Annual Variation ◽  
Hatching Success ◽  
Coniferous Forests ◽  
Chick Survival ◽  
Freshwater Lakes ◽  
Early Start ◽  
Regional Factors

We investigated the breeding success of a Red-throated Diver Gavia stellata population of approximately 70 pairs during ten seasons, 1991–2000, in a 1820 km2 study area, dominated by coniferous forests and mires in Malung, Dalarna in Central Sweden. The majority of the pairs bred in tarns smaller than 1.0 ha and foraged in larger freshwater lakes or rivers up to a distance of 4.6 km. Average breeding success was 0.76 “large” chicks per pair and year, with a declining trend over the study period accompanied by a decline in the proportion of broods with two “large” chicks. Breeding success was higher in seasons with an average early start of incubation and could be related to higher hatching success and survival of chicks. Predation during incubation was probably an important reason for breeding failures, and abandoning or change of breeding tarns were related to breeding failures. The annual variation of the percentage of broods with two “large” chicks was synchronised between pairs foraging at different fishing lakes, which indicates the influence of some large-scale regional factors linked to the availability of food. Chick survival in two-chicks broods was significantly lower than in one-chick broods. The declining trend in breeding success is an incitement for future monitoring, and any link to impaired foraging conditions needs to be more closely addressed.

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