In this post, I will review some of the scientific papers recently published in ornithology journals.\u00a0 All of the articles involve birds that occur in Maine although the research was done elsewhere.<\/p>\n
Canada Geese females usually lay between seven and nine eggs.\u00a0 The young all hatch at the same time, even though females can only lay one egg a day.\u00a0 One might think that the female would not start to incubate the eggs until the last one is laid so the eggs would develop at the same rate.\u00a0 Yet, females start to incubate at day three.\u00a0 How can those eggs laid later possibly catch up?<\/p>\n
The mystery was solved by Mark Clark and colleagues as described in a recent Condor article.\u00a0 They showed that the female adjusts the structure of the egg shell depending on when in the sequence an egg is laid.\u00a0 Eggs laid later had shells that were more porous and better conductors of heat than shells of early eggs.\u00a0 The later eggs absorb more heat from the incubating mother and grow more rapidly than the chicks in early eggs.\u00a0 The result is that all chicks end up ready to hatch together.<\/p>\n
Birders know that municipal dumps and landfills are great places to look for gulls.\u00a0 A large mound of garbage can attract hundreds of Herring Gulls, Ring-billed Gulls, and Great-black Backed Gulls.\u00a0 Often a few Iceland Gulls and Glaucous Gulls can be present outside of their nesting season. Despite the attraction of gulls for garbage, surprisingly little work has been done to determine if this supplemental food improves gull survival and reproduction.\u00a0 (Landfills are a different kind of feeding station!).\u00a0 A recent paper in the Condor by Emily Weiser and Abby Powell examined\u00a0the importance of garbage on the survival and nesting success of Glaucous Gulls in Alaska.\u00a0 Their results should be applicable to Maine.<\/p>\n
They studied ten Glaucous Gull colonies in Alaska.\u00a0 Some colonies were within three miles of a landfill, others as far as 45 miles away.\u00a0 Garbage could be detected in the pellets of 85% of the gulls close to landfills.\u00a0 Weiser and Powell found a very strong effect of garbage on nesting success.\u00a0 Gulls who got most of their food from garbage fledged more young.\u00a0 Although garbage likely allows gull populations to grow, the presence of garbage may benefit the shorebirds and waterfowl that Glaucous Gulls normally feed on by reducing their predation risk.<\/p>\n
The Saltmarsh Sparrow reaches its northern nesting limit in southern Maine.\u00a0 This species is unusual compared to most songbirds because individuals do not form pair bonds and they are not territorial.\u00a0 The female provides all the parental care to the offspring.<\/p>\n
Some observations suggest that Saltmarsh Sparrow nests tend to occur in clusters or \u201chotspots\u201d.\u00a0\u00a0 Some workers claimed that these clusters are associated with particular characteristics of the marsh that provide the best nesting microhabitat.<\/p>\n
In a recent Auk article, Trina Bayard and Chris Elphick studied two populations of Saltmarsh Sparrows in two Connecticut salt marshes adjacent to Long Island Sound. Their goal was to rigorously test the claim that Saltmarsh Sparrow nests are clustered.\u00a0 They sought to find evidence that vegetation differences across the marshes and the presence of other Saltmarsh Sparrow nests might influence nest site selection.<\/p>\n
They found 213 nests and documented the characteristics of the vegetation around each nest.\u00a0 They found that neither the proximity of other nests or vegetation characteristics influenced nest site selection.\u00a0 In other words, the nests occur randomly in the two marshes.\u00a0 A careful study put paid to the claim that Saltmarsh Sparrows nest together.<\/p>\n
Bicknell\u2019s Thrushes nest in dense fir and red spruce habitat just below tree line in northern New England, the Adirondacks, Quebec and the Maritime Provinces.\u00a0\u00a0 The species winters in the Greater Antilles, primarily on Hispaniola.\u00a0 Because of the low population size and the restricted areas for both nesting and wintering, Bicknell\u2019s Thrushes rank high on species of concern lists.<\/p>\n
Little was known about the wintering behavior of this species until a recent article in the Auk by Jason Townsend and colleagues provided important new information.\u00a0 These authors studied two populations of wintering Bicknell\u2019s Thrushes in the Dominican Republic on Hispaniola, one at a mid-elevation rainforest site and one at a high-elevation cloud-forest site.\u00a0 The birds at the lower site primarily fed on fruits while the cloud-forest birds fed mostly on insects and other arthropods.\u00a0 In both cases, the birds maintained solitary territories; a male or a female defended its territory from all comers.\u00a0 The results suggest that both fruits and arthropods are resources that are worth defending for wintering thrushes.<\/p>\n
[Originally published on December 12, 2010]<\/p>\n\n
In this post, I will review some of the scientific papers recently published in ornithology journals.\u00a0 All of the articles involve birds that occur in Maine although the research was done elsewhere. Canada Geese females usually lay between seven and nine eggs.\u00a0 The young all hatch at the same time, even though females can only […]<\/p>\n","protected":false},"author":146,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_s2mail":"","ngg_post_thumbnail":0,"footnotes":""},"categories":[430,424,433],"tags":[],"builder_content":"","_links":{"self":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts\/358"}],"collection":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/users\/146"}],"replies":[{"embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/comments?post=358"}],"version-history":[{"count":2,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts\/358\/revisions"}],"predecessor-version":[{"id":360,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts\/358\/revisions\/360"}],"wp:attachment":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/media?parent=358"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/categories?post=358"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/tags?post=358"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}