AVIS-IBIS

Birds of Indian Subcontinent

Variation in Laying Date and Clutch Size: The Everglades Environment and the Endangered Cape Sable Seaside Sparrow (Ammodramus Maritimus Mirabilis)

Publication Type:Journal Article
Year of Publication:2011
Authors:Boulton, RL, Baiser, B, Davis, MJ, Virzi,, Thomas, Lockwood, JL
Journal:The Auk
Volume:128
Issue:2
Date Published:2011
ISBN Number:0004-8038
Keywords:Ammodramus, Ammodramus maritima, Ammodramus maritimus, Ammospiza, Ammospiza maritima, Ammospiza maritimus, Emberizidae, Florida
Abstract:ABSTRACT . When to commence breeding is a fundamental decision made by individuals that inhabit seasonal environments. Although photoperiod determines the timing of breeding in most temperate zones, other abiotic conditions can also play a significant role by influencing food availability and, consequently, reproductive performance throughout a breeding cycle. This study used the multibrooded endangered Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis) to test whether water conditions (rainfall and groundwater levels) influenced breeding variables in a subtropical environment, the Florida Everglades. Timing of breeding was related to rainfall preceding the breeding season, with females initiating nesting up to 1 month earlier in years with greater rainfall. Clutch size averaged 3.4 eggs, and females showed an increase in clutch size as the breeding season progressed and in response to higher groundwater levels during the laying period. This effect was more apparent for first nesting attempts, with drier conditions limiting clutch size. Although wetter conditions favored earlier breeding and larger clutch sizes, annual nest survival (range: 12?36%) was negatively associated with high average rainfall late in the breeding season. Clutch-size variation and high nest survival in Cape Sable Seaside Sparrows' first nesting attempts suggests that food-mediated processes affect their reproductive decisions early in the breeding season, whereas predator-mediated processes drove overall reproductive output, possibly through increased activity of major nest predators during wetter conditions.ABSTRACT . When to commence breeding is a fundamental decision made by individuals that inhabit seasonal environments. Although photoperiod determines the timing of breeding in most temperate zones, other abiotic conditions can also play a significant role by influencing food availability and, consequently, reproductive performance throughout a breeding cycle. This study used the multibrooded endangered Cape Sable Seaside Sparrow (Ammodramus maritimus mirabilis) to test whether water conditions (rainfall and groundwater levels) influenced breeding variables in a subtropical environment, the Florida Everglades. Timing of breeding was related to rainfall preceding the breeding season, with females initiating nesting up to 1 month earlier in years with greater rainfall. Clutch size averaged 3.4 eggs, and females showed an increase in clutch size as the breeding season progressed and in response to higher groundwater levels during the laying period. This effect was more apparent for first nesting attempts, with drier conditions limiting clutch size. Although wetter conditions favored earlier breeding and larger clutch sizes, annual nest survival (range: 12?36%) was negatively associated with high average rainfall late in the breeding season. Clutch-size variation and high nest survival in Cape Sable Seaside Sparrows' first nesting attempts suggests that food-mediated processes affect their reproductive decisions early in the breeding season, whereas predator-mediated processes drove overall reproductive output, possibly through increased activity of major nest predators during wetter conditions.
URL:http://www.bioone.org/doi/abs/10.1525/auk.2011.10201
Short Title:The Auk
Taxonomic name: 
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith