Blackpoll Warbler (Dendroica striata) Fat Deposition in Southern Nova Scotia during Autumn Migration

2001 ◽  
Vol 8 (2) ◽  
pp. 149 ◽  
Author(s):  
Andrew K. Davis
Author(s):  
Zoe Lucas ◽  
Andrew Hebda

Three lasiurine bat species, Lasionycteris noctivagans (Silver-hairedBat), Lasiurus cinereus (Hoary Bat), and Lasiurus borealis (Red Bat),have been recorded in inland, coastal, and offshore locations as of NovaScotia. Although these records occurred over a century, 70% are from themid-1990s or later, largely because of research in mainland Nova Scotia,and increased interest on Sable Island. The 65 records presented hereinclude 11, 25, and 29 for Silver-haired, Hoary, and Red bats, respectively,of which 31 are previously unpublished. Seventy-seven percent of recordsare from August through November, the autumn migration period forlasiurine bats. These observations suggest that most autumn occurrencesof these species in Nova Scotia are not extralimital, but are part of normalmigratory patterns in the province.


2001 ◽  
Vol 204 (7) ◽  
pp. 1361-1367 ◽  
Author(s):  
P.J. Butler ◽  
A.J. Woakes

We have tested the hypothesis that a large (2 kg) migratory bird, such as the barnacle goose Branta leucopsis, becomes hypothermic before its autumn migration, when food is not scarce, but when it is necessary to conserve and/or store energy in the form of fat. Abdominal temperature (T(ab)) was measured in wild geese using an implanted data logger. Commencing a few days before and continuing until approximately 20 days after the start of their autumn migration, mean daily T(ab) fell progressively by 4.4 degrees C. Thus, it is suggested that, rather than increasing the rate of pre-migratory fattening, the energy saved as a result of this hypothermia reduces the rate at which fat is used and thus enables its more rapid replacement following and, possibly during, migration. The energy saved may also be used for the replacement of non-fat tissues such as the locomotory muscles and gastro-intestinal tract. These observations are the first of their kind from birds in their natural environment and, together with other data, demonstrate that hypothermia in endotherms is not necessarily related to extremely low environmental temperature, to shortage of food or to the resting phase of the daily cycle. The data also highlight the relationship between hypothermia and fat deposition over extended periods in relatively large, endothermic animals and may have some relevance to obesity in humans.


The Condor ◽  
2003 ◽  
Vol 105 (3) ◽  
pp. 496-504 ◽  
Author(s):  
Colleen Dwyer Heise ◽  
Frank R. Moore

AbstractThe ability to satisfy the energy requirements of migration and to cope with problems that arise en route is likely to be age dependent. We studied hatch-year (HY) and after-hatch-year (AHY) Gray Catbirds (Dumetella carolinensis) to determine if differences in foraging efficiency and molt affected fat deposition prior to autumn migration. Hatch-year catbirds were less efficient foragers than AHY catbirds; however, efficiency improved with age to the extent that many HY catbirds are probably as efficient as AHY birds by the time they commence migration. We discovered age-dependent patterns of fat deposition, which probably resulted from differences in foraging efficiency and molt timing. Hatch-year catbirds began to deposit fat sooner than AHY catbirds but did so more slowly throughout the postbreeding and premigratory phases of the annual cycle. Adult catbirds did not become hyperphagic until they neared the completion of their molt, then deposited fat rapidly.Diferencias Relacionadas con la Edad en la Eficiencia de Forrajeo, Muda y Almacenamiento de Grasas en Dumetella carolinensis antes de la Migración OtoñalResumen. Es probable que la habilidad de satisfacer los requerimientos energéticos de la migración y de sobrellevar problemas surgidos durante ésta, esté relacionada con la edad. Estudiamos individuos de la especie Dumetella carolinensis en su año de eclosión (AE) y de más de un año post-eclosión (PAE) para determinar si las diferencias en la eficiencia de forrajeo y en muda afectan el almacenamiento de grasas antes de la migración otoñal. Las aves AE forrajearon menos eficientemente que las PAE, pero la eficiencia aumentó con la edad de manera que muchas aves AE eran probablemente tan eficientes como las PAE en el momento en que iniciaron la migración. Descubrimos patrones dependientes de la edad en el almacenamiento de grasas, que probablemente fueron el resultado de las diferencias en la eficiencia de forrajeo y el momento de la muda. Los individuos AE comenzaron a almacenar grasas antes que los PAE, pero lo hicieron a una tasa menor a lo largo de las fases postreproductiva y premigratoria del ciclo anual. En cambio, las aves adultas no se volvieron hiperfágicas hasta que estaban cerca de completar la muda; luego, almacenaron grasas rápidamente.


Bird-Banding ◽  
1972 ◽  
Vol 43 (2) ◽  
pp. 85 ◽  
Author(s):  
G. Page ◽  
A. L. A. Middleton

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