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An exception to the rule: carry-over effects do not accumulate in a long-distance migratory bird.

Senner NR, Hochachka WM, Fox JW, Afanasyev V - PLoS ONE (2014)

Bottom Line: We found that individual godwits could migrate progressively later than population mean over the course of an entire migration period, especially southbound migration, but that these deviations did not accumulate across the entire year and were not consistently detected among individuals across years.Furthermore, neither the accumulation of lateness during previous portions of the annual cycle nor arrival date at the breeding grounds resulted in individuals suffering reductions in their breeding success or survival.Given their extreme life history, such a lack of carry-over effects suggests that strong selection exists on godwits at each stage of the annual cycle and that carry-over effects may not be able to persist in such a system, but also emphasizes that high-quality stopover and wintering sites are critical to the maintenance of long-distance migratory populations.

View Article: PubMed Central - PubMed

Affiliation: Cornell Lab of Ornithology, Cornell University, Ithaca, New York, United States of America.

ABSTRACT
Recent years have seen a growing consensus that events during one part of an animal's annual cycle can detrimentally affect its future fitness. Notably, migratory species have been shown to commonly display such carry-over effects, facing severe time constraints and physiological stresses that can influence events across seasons. However, to date, no study has examined a full annual cycle to determine when these carry-over effects arise and how long they persist within and across years. Understanding when carry-over effects are created and how they persist is critical to identifying those periods and geographic locations that constrain the annual cycle of a population and determining how selection is acting upon individuals throughout the entire year. Using three consecutive years of migration tracks and four consecutive years of breeding success data, we tested whether carry-over effects in the form of timing deviations during one migratory segment of the annual cycle represent fitness costs that persist or accumulate across the annual cycle for a long-distance migratory bird, the Hudsonian godwit, Limosa haemastica. We found that individual godwits could migrate progressively later than population mean over the course of an entire migration period, especially southbound migration, but that these deviations did not accumulate across the entire year and were not consistently detected among individuals across years. Furthermore, neither the accumulation of lateness during previous portions of the annual cycle nor arrival date at the breeding grounds resulted in individuals suffering reductions in their breeding success or survival. Given their extreme life history, such a lack of carry-over effects suggests that strong selection exists on godwits at each stage of the annual cycle and that carry-over effects may not be able to persist in such a system, but also emphasizes that high-quality stopover and wintering sites are critical to the maintenance of long-distance migratory populations.

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Map showing the migration routes of Hudsonian godwits breeding at Beluga River, Alaska.Twenty-six individuals were tracked across three years 2009–2012, though for ease of presentation this map only shows those from 2009–2010 (n = 12), using British Antarctic Survey Mk-14 geolocation-tracking devices. Each red triangle denotes the location of an individual on one day, but does not necessarily indicate that the individual stopped in that location. Each blue circle denotes a region in which the majority of godwits stopped and congregated in both years. From north to south, those regions are: Beluga River, Alaska (nesting site); central Saskatchewan (staging site southward migration); Rainwater Basin, Nebraska (staging site northward migration); Amazon Basin, Colómbia (stopover site southward migration); Buenos Aires Province, Argentina (stopover site southward migration); and Isla Chiloé, Chile (nonbreeding site). Note that the typical annual migratory route is a clock-wise loop.
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pone-0086588-g001: Map showing the migration routes of Hudsonian godwits breeding at Beluga River, Alaska.Twenty-six individuals were tracked across three years 2009–2012, though for ease of presentation this map only shows those from 2009–2010 (n = 12), using British Antarctic Survey Mk-14 geolocation-tracking devices. Each red triangle denotes the location of an individual on one day, but does not necessarily indicate that the individual stopped in that location. Each blue circle denotes a region in which the majority of godwits stopped and congregated in both years. From north to south, those regions are: Beluga River, Alaska (nesting site); central Saskatchewan (staging site southward migration); Rainwater Basin, Nebraska (staging site northward migration); Amazon Basin, Colómbia (stopover site southward migration); Buenos Aires Province, Argentina (stopover site southward migration); and Isla Chiloé, Chile (nonbreeding site). Note that the typical annual migratory route is a clock-wise loop.

Mentions: Individual godwits repeatedly made non-stop flights of longer than 10,000 km and 7 days during their northbound migrations and flights of longer than 5 days and 6,500 km during their southbound migrations (Fig. 1). We found almost no inter-annual variation in migratory pathways. All but 2 of the 26 individuals stopped in the same suite of 6 regions each year — Beluga River (breeding site); central Saskatchewan (staging site during southward migration); Amazon Basin, Colómbia (stopover site during southward migration); Buenos Aires Province, Argentina (stopover site during southward migration); Isla Chiloé, Chile (nonbreeding site); and Rainwater Basin, Nebraska (staging site during northward migration). Beginning with departure from the breeding grounds in Beluga River each year, we were able to calculate mean annual population arrival and departure dates at each stopover site, as well as deviations in timing from these population averages for each individual (Table 1).


An exception to the rule: carry-over effects do not accumulate in a long-distance migratory bird.

Senner NR, Hochachka WM, Fox JW, Afanasyev V - PLoS ONE (2014)

Map showing the migration routes of Hudsonian godwits breeding at Beluga River, Alaska.Twenty-six individuals were tracked across three years 2009–2012, though for ease of presentation this map only shows those from 2009–2010 (n = 12), using British Antarctic Survey Mk-14 geolocation-tracking devices. Each red triangle denotes the location of an individual on one day, but does not necessarily indicate that the individual stopped in that location. Each blue circle denotes a region in which the majority of godwits stopped and congregated in both years. From north to south, those regions are: Beluga River, Alaska (nesting site); central Saskatchewan (staging site southward migration); Rainwater Basin, Nebraska (staging site northward migration); Amazon Basin, Colómbia (stopover site southward migration); Buenos Aires Province, Argentina (stopover site southward migration); and Isla Chiloé, Chile (nonbreeding site). Note that the typical annual migratory route is a clock-wise loop.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921144&req=5

pone-0086588-g001: Map showing the migration routes of Hudsonian godwits breeding at Beluga River, Alaska.Twenty-six individuals were tracked across three years 2009–2012, though for ease of presentation this map only shows those from 2009–2010 (n = 12), using British Antarctic Survey Mk-14 geolocation-tracking devices. Each red triangle denotes the location of an individual on one day, but does not necessarily indicate that the individual stopped in that location. Each blue circle denotes a region in which the majority of godwits stopped and congregated in both years. From north to south, those regions are: Beluga River, Alaska (nesting site); central Saskatchewan (staging site southward migration); Rainwater Basin, Nebraska (staging site northward migration); Amazon Basin, Colómbia (stopover site southward migration); Buenos Aires Province, Argentina (stopover site southward migration); and Isla Chiloé, Chile (nonbreeding site). Note that the typical annual migratory route is a clock-wise loop.
Mentions: Individual godwits repeatedly made non-stop flights of longer than 10,000 km and 7 days during their northbound migrations and flights of longer than 5 days and 6,500 km during their southbound migrations (Fig. 1). We found almost no inter-annual variation in migratory pathways. All but 2 of the 26 individuals stopped in the same suite of 6 regions each year — Beluga River (breeding site); central Saskatchewan (staging site during southward migration); Amazon Basin, Colómbia (stopover site during southward migration); Buenos Aires Province, Argentina (stopover site during southward migration); Isla Chiloé, Chile (nonbreeding site); and Rainwater Basin, Nebraska (staging site during northward migration). Beginning with departure from the breeding grounds in Beluga River each year, we were able to calculate mean annual population arrival and departure dates at each stopover site, as well as deviations in timing from these population averages for each individual (Table 1).

Bottom Line: We found that individual godwits could migrate progressively later than population mean over the course of an entire migration period, especially southbound migration, but that these deviations did not accumulate across the entire year and were not consistently detected among individuals across years.Furthermore, neither the accumulation of lateness during previous portions of the annual cycle nor arrival date at the breeding grounds resulted in individuals suffering reductions in their breeding success or survival.Given their extreme life history, such a lack of carry-over effects suggests that strong selection exists on godwits at each stage of the annual cycle and that carry-over effects may not be able to persist in such a system, but also emphasizes that high-quality stopover and wintering sites are critical to the maintenance of long-distance migratory populations.

View Article: PubMed Central - PubMed

Affiliation: Cornell Lab of Ornithology, Cornell University, Ithaca, New York, United States of America.

ABSTRACT
Recent years have seen a growing consensus that events during one part of an animal's annual cycle can detrimentally affect its future fitness. Notably, migratory species have been shown to commonly display such carry-over effects, facing severe time constraints and physiological stresses that can influence events across seasons. However, to date, no study has examined a full annual cycle to determine when these carry-over effects arise and how long they persist within and across years. Understanding when carry-over effects are created and how they persist is critical to identifying those periods and geographic locations that constrain the annual cycle of a population and determining how selection is acting upon individuals throughout the entire year. Using three consecutive years of migration tracks and four consecutive years of breeding success data, we tested whether carry-over effects in the form of timing deviations during one migratory segment of the annual cycle represent fitness costs that persist or accumulate across the annual cycle for a long-distance migratory bird, the Hudsonian godwit, Limosa haemastica. We found that individual godwits could migrate progressively later than population mean over the course of an entire migration period, especially southbound migration, but that these deviations did not accumulate across the entire year and were not consistently detected among individuals across years. Furthermore, neither the accumulation of lateness during previous portions of the annual cycle nor arrival date at the breeding grounds resulted in individuals suffering reductions in their breeding success or survival. Given their extreme life history, such a lack of carry-over effects suggests that strong selection exists on godwits at each stage of the annual cycle and that carry-over effects may not be able to persist in such a system, but also emphasizes that high-quality stopover and wintering sites are critical to the maintenance of long-distance migratory populations.

Show MeSH
Related in: MedlinePlus