Winter gardens and bird reproductive success.

[Gloria]

More on how a native garden left to winter over will enhance a wildlife garden. From birds and butterflies and caterpillars, to assassin bugs, praying mantises, lace wings, wolf spiders, minute pirate bugs, damsel bugs, ground beetles, ladybugs and more...can live through the winter in your garden if you leave them undisturbed. A bird family paradise when looking for nesting.

The Wildlife Value of A Messy Garden | Habitat Network

The conditions of winter habitat for migrating birds, it turns out, are a crucial part of their survival and reproductive success in the spring. Savannah Sparrows, pictured above, were studied in their wintering grounds of the southern United States. The birds turned out to be very sensitive to climatic changes in their wintering habitats. In particular, their ability to access reliable food resources essential during long periods of cold or unusual weather influenced their breeding success in the spring. Gardens rich in shriveled fruits and abundant seedheads help these migratory birds survive not only winter, but spring breeding.

[Gloria]

If you find this stuff interesting to read here is a link that shows correlation between good winter habitat and reproductive success in spring. To see if it was the individual bird or the habitat quality at work, American redstarts were removed from quality habitat territory and redstarts from lesser quality sites allowed to take over. These birds with more and better food and cover were able to increase health and weight in the better territory so as to be ready to leave for breeding grounds a bit earlier than those birds in other lesser quality winter grounds. This in turn favored the reproductive success in the breeding grounds.

https://static1.squarespace.com/stat...+2009+PRSB.pdf

[Gloria]

http://www.journals.uchicago.edu/doi/abs/10.1086/284880

Abstract... Animal and plant populations often occupy a variety of local areas and may experience different local birth and death rates in different areas. When this occurs, reproductive surpluses from productive source habitats may maintain populations in sink habitats, where local reproductive success fails to keep pace with local mortality. For animals with active habitat selection, an equilibrium with both source and sink habitats occupied can be both ecologically and evolutionarily stable. If the surplus population of the source is large and the per capita deficit in the sink is small, only a small fraction of the total population will occur in areas where local reproduction is sufficient to compensate for local mortality. In this sense, the realized niche may be larger than the fundamental niche. Consequently, the particular species assemblage occupying any local study site may consist of a mixture of source and sink populations and may be as much or more influenced by the type and proximity of other habitats as by the resources and other conditions at the site.

[Gloria]

| Proceedings of the Royal Society of London B: Biological Sciences

Abstract
Although predicted some time ago, there has been little success in demonstrating that the overall fitness of migratory birds depends on the combined influences of their experiences over all seasons. We used stable carbon isotope signatures (δ13C) in the claws of migrating black–throated blue warblers Dendroica caerulescens to infer their wintering habitats and investigated whether winter habitat selection can be linked to condition during migration. Resident bird species with low δ13C corresponded to selection of more mesic habitats, and migrating birds with low δ13C were in better condition than conspecifics with higher δ13C signatures. These findings concur with empirical observations on the wintering grounds, where dominants (mostly males) tend to exclude subordinates from mesic areas (considered to be high–quality habitats). We believe that variation in condition during migration may be one of the key factors determining differences in arrival times and condition at the breeding areas, which in turn have a major influence on reproductive success

[Gloria]

Reproductive Success of Migratory Birds in Habitat Sources and Sinks - Donovan - 1995 - Conservation Biology - Wiley Online Library

Abstract
Fragmentation of breeding habitat in North America has been implicated in the decline of forestnesting, Neotropical migrant birds. We used a comparative approach to examine the effects of fragmentation on three forest-nesting migrants: Ovenbird (Seiurus aurocapillus), Red-eyed Vireo (Vireo olivaceus), and Wood Thrush (Hylocichla mustelina). We surveyed birds and monitored reproductive success on 28 study plots in fragmented and contiguous forests in two midwestern regions. Distribution of individuals between fragmented and contiguous forests appeared to vary among species and regions, but total nest failure was significantly higher infragments than contiguous forests in both regions for all species (p = 0.053). We attributed greater nest failure to increased nest predation (p = 0.093) and increased brood parasitism by the Brown-headed Cowbird (Molothrus ater, p= 0.009). In addition to greater total nest failure, partial nest failure due to cowbird parasitism led to a reduction in the number of host fledglings. Although the causes of nest mortality appeared to be species specific, total nest failure and partial nest failure acted in concert to reduce the number of offspring per adult for all three species on fragments. We used simple population growth models to assess the viability of the three species infragmented and contiguous habitats in both regions. In general, populations on fragments appeared to be population sinks and populations on continguous forests appeared to be population sources. Assuming constant mortality during winter, projected growth indicated that without immigration Ovenbird and Red-eyed Vireo populations should become extinct on fragments in both regions and Wood Thrush populations should be maintained or slightly decline on fragments. Populations of all three species should increase in contiguous habitats in both regions without emigration. We suggest that habitat fragmentation reduces local reproduction and may have ramifications for the entire population. A clear understanding of population demography depends on examination of demographic dynamics within and among sources and sinks. We emphasize that the long-term viability of these species depends on maintaining large tracts of forest throughout the breeding range until the spatial scale at which source and sink populations interact can be determined

[jack]

Originally Posted by Gloria

Reproductive Success of Migratory Birds in Habitat Sources and Sinks - Donovan - 1995 - Conservation Biology - Wiley Online Library

Thanks, Gloria. So much information; sweet! I can say, also, that I scored high on my self delivered test: I am a messy gardener!!! Glad I'm doing something right!!!

[Leslie]

I'm a messy gardener, too -- I like those leaves and dried flowers! And I enjoy watching the birds digging through the leaves. I'm glad to see it's a good thing.