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Clutch size, brood size and brood emergence in the Marbled Teal Marmaronetta angustirostris in the Marismas del Guadalquivir, southwestern Spain
Author(s) -
GREEN ANDY J.
Publication year - 1998
Publication title -
ibis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 80
eISSN - 1474-919X
pISSN - 0019-1019
DOI - 10.1111/j.1474-919x.1998.tb04713.x
Subject(s) - avian clutch size , biology , anatidae , brood , ecology , hatching , range (aeronautics) , seasonal breeder , zoology , nest (protein structural motif) , reproduction , biochemistry , materials science , composite material
The first detailed study of the breeding biology of the globally threatened Marbled Teal Marmaronetta angustirostris is presented, using data from the Marismas del Guadalquivir in southwestern Spain. Complete clutches, with 9–20 eggs, were recorded from 28 April to 27 July. Excluding clutches of over 14 eggs (likely to be intraspecifically parasitized), the mean clutch size was 11.8, larger than that reported for almost all other Anatidae species. Broods hatched from May to early August (later than sympatric duck species), with a peak in mid‐late June and significant annual variation in date. Brood sizes were exceptionally high, declining from a mean of 10.9 in the first week of age to 8.5 when fully feathered (at 42 days or more). Duckling mortality was concentrated in the first 2 weeks after hatching. Nine percent of broods had 15–23 ducklings, largely as a result of nest parasitism. Brood size decreased strongly with hatching date and varied significantly between years. Data from across the species' range showed that breeding occurs later at more northerly latitudes. A recent decline in the Marbled Teal in the Marismas is linked with its late breeding season. Anthropogenic changes have reduced the duration of flooding in the natural marshes of Donana National Park, which now dry out by August, before this species has completed breeding