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- Nilsson, Leif, et al.
(författare)
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Change of mate in a Greylag Goose Anser anser population effects of timing on reproductive success
- 2001
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Ingår i: Wildfowl. - 0954-6324. ; , s. 31-40
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Tidskriftsartikel (refereegranskat)abstract
- The population of the West Baltic Greylag Goose Anser anser is migratory,breeding in southwest Scania, southernmost Sweden and wintering in theGuadalquivir Marismas, southwest Spain, or in the Dutch Delta. This populationhas been the subject of a long-term study o f a sample o f neck cottaredindividuals, and observations o f marked individuals were used to assessrates of mate fid e lity in this supposedly long-term monogamous species.The annual divorce rate during the years 1985-2000 was 10.5% [n-415], with29.7% of alt pairs ending in a divorce [n=158¡. A fte r divorce or death of thepartner, birds re-paired assortatively with individuals from th e ir own breedingarea, using the same wintering area. New p a ir bonds formed on thebreeding area, during one of three periods; ju s t a fte r re tu rn in spring, ju s ta fte r m o u lt and ju s t before departure in autumn. Divorce o r p a rtn e r deathduring the period 15 October - 28 February, when breeders were away fromthe breeding grounds, resulted in a significantly tower reproductive successduring the following breeding season, compared to mate losses during theperiod 1 June - 14 October.
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| 4. |
- Nilsson, Leif, et al.
(författare)
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Changes in numbers of staging and wintering geese in Sweden : 1977/78-2019/20
- 2020
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Ingår i: Wildfowl. - 0954-6324. ; :70, s. 107-126
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Tidskriftsartikel (refereegranskat)abstract
- Regular goose counts made throughout Sweden since 1977/78 show that the total numbers staging and wintering in the country have increased markedly over the decades. October totals were of 51,000 geese in 1977, rising to c. 600,000 in 2018, during which time January totals also increased from 31,000 to 252,000 birds. The greatest change recorded was for the Greylag Goose Anser anser, numbers of which rose from 20,000 to > 250,000 individuals over a 35-year period. Changes in migration and wintering habits have also been recorded, with mid-winter (January) Greylag Goose numbers now amounting to 20-33% of the September totals in recent years, illustrating increases in the proportion of the population now wintering in the country. Moreover, large numbers of Barnacle Geese Branta leucopsis have started to stage and over-winter in Sweden, and are now becoming the commonest species, with 365,000 recorded in autumn 2019.
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- Nilsson, Leif, et al.
(författare)
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Field choice in spring and breeding performance of Greylag Geese Anser anser in Southern Sweden.
- 2002
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Ingår i: Wildfowl. - 0954-6324. ; 53, s. 7-25
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Tidskriftsartikel (refereegranskat)abstract
- Selection and exploitation of feeding areas by pre-breeding and nonbreeding Greylag Geese A nser anser, as we ll as by families, was studied in a breeding area consisting of four lakes in Scania, southernmost Sweden, in the years 1997-2000. Total production of young in each lake as we ll as the breeding performance of neck collared individuals was established annually, 1985-2000. This breeding population increased on average 15.3% p e ra n n um, from 93 pairs in 1985 to 910 pairs in 2001. The two main field types used by pre-breeding pairs, males of incubating females and non-breeders in flocks were win te r wheat and grassland, often switching from the fo rme r to the latter in mid-season. Almost all feeding during brood- rearing took place on pastures grazed by livestock or on a golf-course. Generally in spring, the rates of exploitation were below 300-400 goose days ha"1, but rates of >1,000 goose days ha' 1 were noted for one cereal field and two grassland areas. The rates of exploitation by families varied markedly among brood-rearing areas as we ll as years, being highest all through the study period on a grazed pasture, where it ranged 800-1,350 goose days ha'1. Including the utilisation by non-breeders, the annual exploitation of this pasture ranged from 1,400 to 2,500 goose days h a 1. At the only lake without grazing by livestock (since the mid-1990s), significantly fewer goslings survived to fledging than at the other lakes (45% vs 70%). Indications of density-dependent effects on the productivity of sma ll young were noted at one of the lakes (Klosterviken) but not at another (Yddingen). Most likely, the lack of any density dependent effect, in spite of the very marked increase in the breeding population during the study period at Yddingen, is the result of access to highly fertilized grass on a golf course.
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- Nilsson, Leif, et al.
(författare)
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Fältval hos höstrastande och övervintrande gäss i sydvästra sverige 19 77/1978-2011/2012
- 2013
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Ingår i: Ornis Svecica. - 1102-6812. ; 23:1, s. 46-60
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Tidskriftsartikel (refereegranskat)abstract
- Field choice was recorded during counts of geese in South-west Scania, South Sweden in autumn (October and November) and in winter (January), 1977/1978-2011/2012. Sugar beet spill was the most important field type in autumn and during the last ten years also in winter. Bean Geese Anserfabalis used this food source when the study started while Canada Geese Branta canadensis, Greylag Geese Anser anser, White-fronted Geese Anser albifrons and Barnacle Geese Branta leucopsis followed during the years 1987-2001. Potatoes were mainly used when fields with sugar beet spill were unavailable. Cereal stubbles were mainly used in autumn and to a quite low extent. Winter cereals were heavily used by most species in both autumn and winter during the first 15 years but less so thereafter. Grasslands were mainly used in winter, to a large extent by White-fronted Geese and to a quite high extent by Bean Geese and Barnacle Geese. The total use of oilseed rape was low, mainly by Canada Geese that utilised fields with no-till when the ground was snowcovered.
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- Nilsson, Leif, et al.
(författare)
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Livslång häckningsframgång för grågäss anser anser häckande i södra Sverige.
- 2018
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Ingår i: Ornis Svecica. - : Ornis Svecica. - 1102-6812 .- 2003-2633. ; 28:1, s. 39-47
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Tidskriftsartikel (refereegranskat)abstract
- During 1984–2009, 664 adults and 1,944 goslings of Greylag Geese Anser anser were neck-banded in south-west Scania, Sweden. After hatching the area was careful-ly searched for marked geese, giving more than 100,000 re-sightings. Of those marked as goslings 71% survived the first year, 52% the second year, and the oldest bird recorded was 25 years. About 50% of the survivors were recruited into the breeding population when two to three years old. Of 1,187 geese that survived for at least two years, 25% produced at least one brood of small young, and 18% at least one fledged young. The maximum lifetime number of broods with fledged young was nine, but 50% of the geese known to have bred successfully pro- duced only one brood of fledged young. Ten percent of the geese seen with small goslings produced 47% of all fledged young. The maximum number of fledged young for a goose of known age was 32 (age 15 years), but two geese marked as adults and followed for 16 and 17 years produced 40 fledglings each.
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- Nilsson, Leif, et al.
(författare)
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Lokala rörelser av grågäss Anser anser i södra Sverige utanför häckningstiden
- 2017
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Ingår i: Ornis Svecica. - 1102-6812. ; 27:1, s. 13-22
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Tidskriftsartikel (refereegranskat)abstract
- During 1984–2009, Greylag Geese Anser anser were neck-banded at two lakes six kilometres apart in southwest Scania, southernmost Sweden: 2308 at lake Yddingen and 633 at Klosterviken (part of lake Bör-ringe). Through 2013 we recorded 51 132 and 29 937 re-sightings, respectively. We analyse the distribution patterns within Scania during the post-breeding months July–March. In spite of the short distance between the breeding sites, marked differences in the local distributions were found. In late summer and early autumn, Greylags from Klosterviken stayed longer inland close to the breeding lake than geese from Yddingen, the availability of good inland feeding sites close to Klosterviken explained the difference. In late autumn, when many resightings were made along the western coast, it seemed that the distance from the breeding lake explained some of the differences, geese from Yddingen dominated in the northern part, whereas geese from Klosterviken were found further south. There was also a time difference in that the birds from Yddingen moved to the coast earlier than those from Klosterviken.
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| 9. |
- Nilsson, Leif, et al.
(författare)
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Why should Greylag Goose Anser anser parents rear offspring of others?
- 2003
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Ingår i: Wildfowl. - 0954-6324. ; 54, s. 25-37
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Tidskriftsartikel (refereegranskat)abstract
- The benefits and costs of rearing large broods were studied in a population of neck collared Greylag Geese in Scania, southernmost Sweden. Families were divided into four groups according to brood size: 1-4, 5-8, 9-12 and >12 young. Gosling survival showed a significant positive relationship with brood size on arrival at the rearing area. First-year and third-year local survival, as well as breeding recruitment, showed a significant positive relationships with brood size at fledging. For adults rearing large broods, no costs were detected during the year following that when they fledged >8 young; both survival rate and reproductive success exceeded the long-term averages.
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