| 11. |
- Elmberg, Johan, et al.
(författare)
-
Density dependent breeding success in mallards
- 2003
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Breeding success in wild mallards was studied on small eutrophic nemoral lakes in a two-year cross-over experiment in which wing-clipped conspecifics were added to increase pair density. The number of wild mallards that came to the lakes to nest (prior to introductions) did not differ between years. Introduction treatment led to a significant reduction in brood number in wild mallards, but it did not alter the number of stage 2+ ducklings finally produced on a lake. Introduction had no effect on lake utilization by broods, ducklings and non-breeding adults (cumulative days over the entire breeding season). Abundance of invertebrate prey differed greatly among lakes, but it did not correlate with breeding success. Breeding success was thus subject to sequential density-dependence; i.e. a lower number of broods still produced the same number of 2+ ducklings. We speculate that predation is the most likely process behind both patterns. We conclude that late and snapshot measures of duckling productivity may mask density dependent population processes of fundamental importance to regulation and harvest policy.
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| 12. |
- Elmberg, Johan, 1960-, et al.
(författare)
-
Early breeding teal Anas crecca use the best lakes and have the highest reproductive success
- 2005
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Ingår i: Annales Zoologici Fennici. - 0003-455X .- 1797-2450. ; 42:1, s. 37-43
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Tidskriftsartikel (refereegranskat)abstract
- Teal (Anas crecca) broods were studied in 1988-2003 in a boreal watershed comprising 51 permanent wetlands. Brood size of near-fledged ducklings was negatively related to the hatching date, i.e. early pairs had higher reproductive success than late pairs. However, brood size of newly hatched ducklings was not related to the hatching date, implying that the advantage of early breeding is due to processes operating during the brood stage rather than during nesting. Half of the lakes never produced a brood, and among the 26 lakes that actually did, two `preferred' lakes generated 44% of the broods and 55% of the near-fledged ducklings. Early broods were over-represented on such `preferred' lakes, and late broods over-represented on `less preferred' lakes. Our study suggests that lake selection and early nesting may have important fitness consequences in teal.
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| 13. |
- Elmberg, Johan, et al.
(författare)
-
Early breeding teal Anas crecca use the best lakes and have the highest reproductive success
- 2005
-
Ingår i: Annales Zoologici Fennici. - : Finnish Zoological and Botanical Publishing Board. - 0003-455X. ; 42:1, s. 37-43
-
Tidskriftsartikel (refereegranskat)abstract
- Teal (Anas crecca) broods were studied in 1988-2003 in a boreal watershed comprising 51 permanent wetlands. Brood size of near-fledged ducklings was negatively related to the hatching date, i.e. early pairs had higher reproductive success than late pairs. However, brood size of newly hatched ducklings was not related to the hatching date, implying that the advantage of early breeding is due to processes operating during the brood stage rather than during nesting. Half of the lakes never produced a brood, and among the 26 lakes that actually did, two `preferred' lakes generated 44% of the broods and 55% of the near-fledged ducklings. Early broods were over-represented on such `preferred' lakes, and late broods over-represented on `less preferred' lakes. Our study suggests that lake selection and early nesting may have important fitness consequences in teal.
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| 14. |
- Elmberg, Johan, 1960-, et al.
(författare)
-
Farligt att vara andägg
- 2002
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Ingår i: Svensk jakt. - 0039-6583. ; 140:10, s. 18-20
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 15. |
- Elmberg, Johan, et al.
(författare)
-
Farligt att vara andägg
- 2002
-
Ingår i: Svensk jakt. - 0039-6583. ; 140:10, s. 18-20
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 16. |
- Elmberg, Johan, 1960-, et al.
(författare)
-
Finns det mer andrum?
- 2005
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Ingår i: Svensk jakt. - 0039-6583. ; 143:8, s. 80-82
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 17. |
- Elmberg, Johan, et al.
(författare)
-
Finns det mer andrum?
- 2005
-
Ingår i: Svensk jakt. - 0039-6583. ; 143:8, s. 80-82
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 18. |
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| 19. |
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| 20. |
- Elmberg, Johan, 1960-, et al.
(författare)
-
Hur många får ligga i orubbat bo?
- 2003
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Ingår i: Vår fågelvärld. - 0042-2649. ; :3, s. 28-29
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Tidskriftsartikel (populärvet., debatt m.m.)
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