scholarly journals Migratory connectivity in the context of differential migration

2018 ◽  
Vol 14 (12) ◽  
pp. 20180679 ◽  
Author(s):  
Martins Briedis ◽  
Silke Bauer
Keyword(s):  
Population Dynamics ◽  
Differential Mortality ◽  
Breeding Period ◽  
Migratory Connectivity ◽  
Differential Migration ◽  
Relative Contribution ◽  
Breeding Populations ◽  
Conservation Actions ◽  
Carry Over ◽  
The Times

Understanding how breeding populations are spatially and temporarily associated with one another over the annual cycle has important implications for population dynamics. Migratory connectivity typically assumes that populations mix randomly; yet, in many species and populations, sex-, age- or other subgroups migrate separately, and/or spend the non-breeding period separated from each other—a phenomenon coined differential migration. These subgroups likely experience varying environmental conditions, which may carry-over to affect body condition, reproductive success and survival. We argue that environmental or habitat changes can have disproportional effects on a population's demographic rates under differential migration compared to random mixing. Depending on the relative contribution of each of these subgroups to population growth, environmental perturbations may be buffered (under-proportional) or amplified (over-proportional). Thus, differential migration may result in differential mortality and carry-over effects that can have concomitant consequences for dynamics and resilience of the populations. Recognizing the role of differential migration in migratory connectivity and its consequences on population dynamics can assist in developing conservation actions that are tailored to the most influential demographic group(s) and the times and places where they are at peril.

Survival and recruitment in the population ecology of the endangered Bombina pachypus (Amphibia: Anura)

2018 ◽  
Vol 39 (3) ◽  
pp. 265-274
Author(s):  
Claudio Angelini ◽  
Andrea Tiberi ◽  
Bruno Cari ◽  
Filippo Giachi
Keyword(s):  
Population Dynamics ◽  
Population Growth ◽  
Breeding Site ◽  
Juvenile Dispersal ◽  
Relative Contribution ◽  
Annual Population ◽  
Conservation Concern ◽  
Local Recruitment ◽  
Effective Conservation ◽  
High Recruitment

Abstract Global amphibian decline is a subject of great conservation concern, yet often basic demographic information is absent, which prevents the understanding of population trends and the planning of effective conservation management. We analysed capture-mark-recapture data from six populations of the endangered Bombina pachypus in order to understand the relative contribution of survival and recruitment to population growth, and to assess if any differences exist among populations in terms of their population dynamics. We found that survival was rather high and generally constant among sites, and recruitment was low, with the exception of two single years at one site. Population growth depended on survival on all sites, except the years following high recruitment at one site. Annual population size was generally lower than 30 individuals, but in one site it was estimated to be larger than 50. Our findings suggest that juvenile survival is more important for population dynamics than recruitment from the larval to the juvenile stage. We also suggest that the low recruitment rates we recorded was a result of juvenile dispersal, and that when populations exhibited high recruitment it was due to occasional successful migration or local recruitment. This pattern could represent a way to counterbalance the risk of inbreeding in populations composed of few individuals, a common characteristic of populations of B. pachypus. Finally, we suggest that conservation measures for B. pachypus should be planned at the landscape scale, and should not be limited solely to the breeding site and its close surroundings.

Changes in migration, carry-over effects, and migratory connectivity

2019 ◽  
pp. 93-107 ◽  
Author(s):  
Roberto Ambrosini ◽  
Andrea Romano ◽  
Nicola Saino
Keyword(s):  
Climate Change ◽  
Life Cycle ◽  
Population Size ◽  
Migratory Connectivity ◽  
Negative Effects ◽  
Annual Life Cycle ◽  
Northern Latitudes ◽  
Timing Of Migration ◽  
Tropical Areas ◽  
Carry Over

Studies of the timing (phenology) of bird migration provided some of the first evidence for the effects of climate change on organisms. Since the rate of climate change is uneven across the globe, with northern latitudes experiencing faster warming trends than tropical areas, animals moving across latitudes are subject to diverging trends of climate change at different stages of their annual life cycle, and, consequently, they can become mistimed with the local ecological conditions, with potentially negative effects on population size. This chapter reviews the modifications induced by climate change in different migration traits, like the timing of migration events, the distribution of organisms, and the direction and the speed of movements. It also considers the effects of ecological carry-over effects and migratory connectivity on the response of birds to climate change.

scholarly journals Seasonal survival and migratory connectivity of the Eurasian Oystercatcher revealed by citizen science

The Auk ◽  
2019 ◽  
Vol 136 (1) ◽  
Author(s):  
Andrew M Allen ◽  
Bruno J Ens ◽  
Martijn Van de Pol ◽  
Henk Van der Jeugd ◽  
Magali Frauendorf ◽  
...  
Keyword(s):  
Citizen Science ◽  
Avian Species ◽  
Future Research ◽  
Migratory Connectivity ◽  
Space And Time ◽  
Demographic Rates ◽  
Breeding Populations ◽  
Spatio Temporal ◽  
Using Data ◽  
Model Structures

Abstract Migratory connectivity describes linkages between breeding and non-breeding areas. An ongoing challenge is tracking avian species between breeding and non-breeding areas and hence estimating migratory connectivity and seasonal survival. Collaborative color-ringing projects between researchers and citizen scientists provide opportunities for tracking the annual movements of avian species. Our study describes seasonal survival and migratory connectivity using data from more than 4,600 individuals with over 51,000 observations, predominantly collected by citizen scientists. Our study focuses on the Eurasian Oystercatcher (Haematopus ostralegus), a species that has experienced a substantial and ongoing decline in recent decades. Multiple threats have been described, and given that these threats vary in space and time, there is an urgent need to estimate demographic rates at the appropriate spatio-temporal scale. We performed a seasonal multi-state (5 geographical areas within The Netherlands) live- and dead-recoveries analysis under varying model structures to account for biological and data complexity. Coastal breeding populations were largely sedentary, while inland breeding populations were migratory and the direction of migration varied among areas, which has not been described previously. Our results indicated that survival was lower during winter than summer and that survival was lower in inland areas compared with coastal areas. A concerning result was that seasonal survival of individuals over-wintering in the Wadden Sea, an internationally important site for over-wintering shorebirds, appeared to decline during the study period. We discuss the outcomes of our study, and how citizen science was integral for conducting this study. Our findings identify how the demographic rates of the oystercatcher vary in space and time, knowledge that is vital for generating hypotheses and prioritizing future research into the causes of decline.

scholarly journals Mercury and Stable Isotopes in Feathers Of Audouin's Gulls as Indicators of Feeding Habits and Migratory Connectivity

The Condor ◽  
2007 ◽  
Vol 109 (2) ◽  
pp. 268-275 ◽  
Author(s):  
Carola Sanpera ◽  
Xavier Ruiz ◽  
Rocío Moreno ◽  
Lluís Jover ◽  
Susan Waldron
Keyword(s):  
Trophic Ecology ◽  
Feeding Habits ◽  
Geographical Area ◽  
Future Research ◽  
Migratory Connectivity ◽  
Migration Patterns ◽  
Isotopic Signatures ◽  
Breeding Populations ◽  
Breeding Grounds ◽  
Wintering Areas

Abstract To better understand migratory connectivity between breeding and nonbreeding populations, we analyzed mercury (Hg) and stable isotope signatures of nitrogen (δ15N), carbon (δ13C), and sulfur (δ34S) in Audouin's Gulls (Larus audouinii) breeding in two different colonies, the Ebro Delta (northeastern Spain) and the Chafarinas Islands (southwestern Mediterranean). Although abundant information is available on the biology and trophic ecology of this gull's breeding populations, little is known about migration patterns, distribution in winter, or conditions faced during the nonbreeding period. Analyses were carried out on first primary feathers, grown during the summer while gulls are on the breeding grounds, and mantle feathers, grown during the winter. Different isotopic signatures (δ15N, δ13C, and δ34S) in summer (primary) feathers from each area agree with the observed differences in diet between the two colonies. In winter (mantle) feathers, isotopic signatures did not differ, consistent with a common wintering ground and common diet, although the lack of isotopic basemaps in marine systems precludes assignment to a geographical area of reference. Future research is needed to relate isotopic signatures and Hg values in mantle feathers to trophic ecology in wintering areas. Results for Hg indicate that the excretory role played by primary feathers precludes their use as indicators of trophic ecology.

scholarly journals Migratory connectivity and population-specific migration routes in a long-distance migratory bird

2014 ◽  
Vol 281 (1778) ◽  
pp. 20132897 ◽  
Author(s):  
Christiane Trierweiler ◽  
Raymond H. G. Klaassen ◽  
Rudi H. Drent ◽  
Klaus-Michael Exo ◽  
Jan Komdeur ◽  
...  
Keyword(s):  
Migratory Bird ◽  
Habitat Characteristics ◽  
Sub Saharan Africa ◽  
Migratory Connectivity ◽  
Migration Routes ◽  
Long Distance ◽  
Comprehensive Overview ◽  
Migration System ◽  
Breeding Populations ◽  
Wintering Areas

Knowledge about migratory connectivity, the degree to which individuals from the same breeding site migrate to the same wintering site, is essential to understand processes affecting populations of migrants throughout the annual cycle. Here, we study the migration system of a long-distance migratory bird, the Montagu's harrier Circus pygargus , by tracking individuals from different breeding populations throughout northern Europe. We identified three main migration routes towards wintering areas in sub-Saharan Africa. Wintering areas and migration routes of different breeding populations overlapped, a pattern best described by ‘weak (diffuse) connectivity’. Migratory performance, i.e. timing, duration, distance and speed of migration, was surprisingly similar for the three routes despite differences in habitat characteristics. This study provides, to our knowledge, a first comprehensive overview of the migration system of a Palaearctic-African long-distance migrant. We emphasize the importance of spatial scale (e.g. distances between breeding populations) in defining patterns of connectivity and suggest that knowledge about fundamental aspects determining distribution patterns, such as the among-individual variation in mean migration directions, is required to ultimately understand migratory connectivity. Furthermore, we stress that for conservation purposes it is pivotal to consider wintering areas as well as migration routes and in particular stopover sites.

scholarly journals Continent-wide tracking to determine migratory connectivity and tropical habitat associations of a declining aerial insectivore

2012 ◽  
Vol 279 (1749) ◽  
pp. 4901-4906 ◽  
Author(s):  
Kevin C. Fraser ◽  
Bridget J. M. Stutchbury ◽  
Cassandra Silverio ◽  
Patrick M. Kramer ◽  
John Barrow ◽  
...  
Keyword(s):  
North American ◽  
Agricultural Landscape ◽  
Ground Cover ◽  
Light Level ◽  
Agricultural Landscapes ◽  
Habitat Associations ◽  
Migratory Connectivity ◽  
Population Declines ◽  
Long Distance ◽  
Breeding Populations

North American birds that feed on flying insects are experiencing steep population declines, particularly long-distance migratory populations in the northern breeding range. We determine, for the first time, the level of migratory connectivity across the range of a songbird using direct tracking of individuals, and test whether declining northern populations have higher exposure to agricultural landscapes at their non-breeding grounds in South America. We used light-level geolocators to track purple martins, Progne subis , originating from North American breeding populations, coast-to-coast ( n = 95 individuals). We show that breeding populations of the eastern subspecies, P. s. subis , that are separated by ca . 2000 km, nevertheless have almost completely overlapping non-breeding ranges in Brazil. Most (76%) P. s. subis overwintered in northern Brazil near the Amazon River, not in the agricultural landscape of southern Brazil. Individual non-breeding sites had an average of 91 per cent forest and only 4 per cent agricultural ground cover within a 50 km radius, and birds originating from declining northern breeding populations were not more exposed to agricultural landscapes than stable southern breeding populations. Our results show that differences in wintering location and habitat do not explain recent trends in breeding population declines in this species, and instead northern populations may be constrained in their ability to respond to climate change.

Patterns of differential migration in white-throated sparrows evaluated with isotopic measurements of feathers

2007 ◽  
Vol 85 (3) ◽  
pp. 413-420 ◽  
Author(s):  
Daniel F. Mazerolle ◽  
Keith A. Hobson
Keyword(s):  
Negative Relationship ◽  
Differential Migration ◽  
Zonotrichia Albicollis ◽  
Cold Temperatures ◽  
Migratory Songbirds ◽  
Breeding Grounds ◽  
Arrival Dates ◽  
Wintering Areas ◽  
Spring Arrival ◽  
Carry Over

We used stable isotope techniques to investigate differential migration in the white-throated sparrow ( Zonotrichia albicollis (J.F. Gmelin, 1789)), a short-distance migrant in North America, to clarify hypotheses about patterns and consequences of migration tactics. Sparrows staging in Manitoba, Canada, exhibited sex-biased differential timing of spring arrival and latitude of wintering origin. Specifically, females arrived later and originated from more southern latitudes. Furthermore, there was a negative relationship between wintering latitude and arrival dates of individuals, although this relationship was only present during the second spring of the study, since atypical cold temperatures were associated with a pulse of late-arriving sparrows during the first spring. The negative correlation between wintering latitude and arrival date was also present within males, suggesting that the distribution of males on wintering areas could have carry-over effects to reproduction. This study demonstrates potential links between events occurring on wintering and breeding grounds of migratory songbirds.

Migratory Connectivity of Semipalmated Sandpipers: Winter Distribution and Migration Routes of Breeding Populations

Waterbirds ◽  
2012 ◽  
Vol 35 (1) ◽  
pp. 83-95 ◽  
Author(s):  
Cheri Gratto-Trevor ◽  
R. I. Guy Morrison ◽  
David Mizrahi ◽  
David B. Lank ◽  
Peter Hicklin ◽  
...  
Keyword(s):  
Migratory Connectivity ◽  
Migration Routes ◽  
Winter Distribution ◽  
Breeding Populations ◽  
And Migration ◽  
Semipalmated Sandpipers

scholarly journals Multiple intrinsic markers identify carry-over effects from wintering to breeding sites for three Nearctic–Neotropical migrant swallows

The Auk ◽  
2019 ◽  
Vol 136 (4) ◽  
Author(s):  
Tara L Imlay ◽  
Frédéric Angelier ◽  
Keith A Hobson ◽  
Gabriela Mastromonaco ◽  
Sarah Saldanha ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Annual Cycle ◽  
Structural Equation ◽  
Migratory Birds ◽  
Equation Modeling ◽  
Breeding Period ◽  
Population Declines ◽  
Winter Habitat ◽  
Neotropical Migrant ◽  
Carry Over

Abstract Carry-over effects from one stage of the annual cycle to subsequent stages can have profound effects on individual fitness. In migratory birds, much research has been devoted to examining such effects from the nonbreeding to the breeding period. We investigated potential carry-over effects influencing spring body condition, breeding phenology, and performance for 3 species of sympatric, declining Nearctic–Neotropical migratory swallows: Bank Swallow (Riparia riparia), Barn Swallow (Hirundo rustica), and Cliff Swallow (Petrochelidon pyrrhonota). To examine carry-over effects, we used structural equation modeling and several intrinsic markers, including stable isotope (δ 2H, δ 13C, and δ 15N) and corticosterone (CORTf) values from winter molted-feathers, and changes in telomere length between breeding seasons. We found support for carry-over effects for all 3 species, however, the specific relationships varied between species and sexes. Effects leading to lower breeding performance were only observed in male Bank, female Barn, and female and male Cliff Swallows. In most cases, carry-over effects were attributed to differences in stable isotope values (most commonly with δ 2H) presumably related to differences in winter habitat use, but, for Cliff Swallows, negative carry-over effects were also linked to higher CORTf values and greater rates of telomere shortening. This work provides further support for the potential role of nonbreeding conditions on population declines, and indicates how multiple intrinsic markers can be used to provide information on ecological conditions throughout the annual cycle.

Population dynamics and production effects of sheep lice (Bovicola ovis Schrank) in extensively grazed flocks

2011 ◽  
Vol 51 (8) ◽  
pp. 753 ◽  
Author(s):  
P. J. James ◽  
B. J. Horton ◽  
N. J. Campbell ◽  
D. L. Evans ◽  
J. Winkleman ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Logistic Models ◽  
Economic Loss ◽  
First Year ◽  
Associated Production ◽  
High Solar Radiation ◽  
Apparent Source ◽  
Fleece Weight ◽  
Carry Over ◽  
Production Effects

An experiment was conducted to characterise population dynamics of lice and associated production loss in extensively grazed flocks infested at different times after shearing. Merino wethers were allocated to six groups of 31 sheep. In the first year (Y1), one sheep in each of two groups was infested with 2500 lice at 6 weeks after shearing (September), sheep in two groups were infested at 4 months (December) and two groups remained uninfested. In year 2 (Y2), infestations carried over from Y1, but a lousy sheep was added to each 6-week infestation mob. In year 3 (Y3), the infested mobs were treated and remained lice free, while lousy donor sheep were added to the two previously uninfested mobs. In Y1, lice appeared to die out in one 6-week-infestation group and were found on only two sheep before next shearing in the other. Lice persisted and spread in the two 4-month-infestation flocks, reaching mean counts (±s.e.) of 0.5 (±0.2) and 0.2 (±0.1) per part before shearing. In Y2 and Y3, lice persisted and increased in all infested flocks, reaching mean counts of 2.3 (±0.6), 8.5 (±1.5), 3.6 (±0.6) and 2.8 (±0.7) per part in Y2 and 1.0 (±0.2) and 1.2 (±0.4) per part in Y3. The count of 8.5 was in the flock with both a carry-over infestation and an infestor sheep. Exponential and logistic models were fitted to describe lice increase; differences in fleece derangement reflected louse numbers. Clean fleece weight was higher in flocks without lice in all years (0.12 kg/head in Y1; 0.22 kg/head in Y2 and Y3; P < 0.05). Classer-assigned colour scores (although not measured colour), cott score and line into which the wool was classed also differed significantly (P < 0.05) between infested and non-infested flocks and there was an indication that staple length was reduced in more heavily infested flocks. In spring-shorn flocks in environments with high solar radiation and no lice present at shearing, even if lice subsequently enter the mob, it appears unlikely that they will increase to levels where serious economic loss will be experienced before next shearing. The study also indicated that lice could persist in flocks at levels unlikely to be detected by most commercial wool producers for extended periods, possibly through one season, which may help to explain reports of new infestations with no apparent source.

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