Age and Sex Influence Natal and Breeding Dispersal of Purple Martins

Western Birds ◽  
2021 ◽  
Vol 52 (4) ◽  
pp. 296-310
Author(s):  
Carolyn A. Cook ◽  
Glen T. Hvenegaard ◽  
Geoffrey L. Holroyd ◽  
Hardy Pletz ◽  
Myrna Pearman
Keyword(s):  
Environmental Changes ◽  
Average Distance ◽  
Breeding Site ◽  
Breeding Dispersal ◽  
Dispersal Patterns ◽  
Nest Sites ◽  
Migration Dynamics ◽  
Second Year ◽  
Dispersal Distances ◽  
Age And Sex

Dispersal patterns deepen our understanding of population dynamics. Dispersal by all age and sex classes enhances a species’ ability to respond to environmental changes, such as in habitat availability, artificial nest sites, and climate. The migration dynamics of the eastern subspecies of the Purple Martin (Progne subis subis) are well known, but we know less about its patterns of annual dispersal. We compared the frequency, distance, and direction of dispersal by each age/sex cohort of martins in central Alberta, at the northwestern limit of their breeding range. We used two datasets: (1) adult martins banded in central Alberta as nestlings and encountered during the summers of 2017 and 2018, and (2) records of encounters of banded martins in Canada from 1935 to 2016 from the Canadian Wildlife Service’s Bird Banding Office. In Alberta, 36% of birds dispersed from natal sites (by an average distance of 24 km), most commonly to the northeast. Across Canada, 29% of birds dispersed (by an average distance of 183 km), most commonly to the east and northeast. In Alberta, martins at least two years old dispersed less frequently than yearlings since some older martins returned to their natal site after first breeding elsewhere. Dispersal distances of after-second-year martins, which represent natal plus breeding dispersal, were greater than those of second-year birds, which represent natal dispersal alone. Thus some martins continue to disperse after their second year and do not maintain complete fidelity to a breeding site, which is different from our current understanding.

Modelling survival and breeding dispersal to unobservable nest sites

2016 ◽  
Vol 43 (5) ◽  
pp. 411 ◽  
Author(s):  
Giacomo Tavecchia ◽  
Ana Sanz-Aguilar ◽  
Belinda Cannell
Keyword(s):  
Breeding Site ◽  
Demographic Parameters ◽  
Breeding Dispersal ◽  
Artificial Nests ◽  
Breeding Sites ◽  
Nest Sites ◽  
Local Survival ◽  
Permanent Migration ◽  
Capture Recapture ◽  
Event Capture

Context Demographic parameters in wildlife populations are typically estimated by monitoring a limited number of individuals in observable sites and assuming that these are representative of the whole population. If individuals permanently disperse to unobservable breeding sites, recruitment and immature survival are expected to be negatively biased and breeding-site fidelity cannot be investigated. Aims To develop a method to obtain unbiased estimated of survival, recruitment and breeding dispersal when individuals can move to, or recruit in, unobservable sites. Methods We used the flexibility of multi-event capture–recapture models to estimate dispersal and recruitment to unobservable sites, merging observations made at two sites within the same breeding locations. We illustrated the model with data on little penguin (Eudyptula minor) breeding in artificial as well as in natural nests. Natural nests are unknown or inaccessible and birds in these sites remain unobservable. Encounters at beaches surrounding the colony suggested that marked animals can permanently move to unobservable nests. We built the multi-event model considering two possible states of the individuals (alive breeding in a nest box and alive in a natural nest) and three types of observations (encountered at a nest only, encountered at the beach only and encountered at both places). This model ensured that the breeding dispersal to unobservable places became estimable. Key results Results indicate that the estimated survival was 8% higher than when recaptures at artificial nests were analysed alone. Also, fidelity to artificial nests was 12% lower than to natural nests. This might reflect the greater availability of natural sites or, alternatively, a heterogeneity between these two types of nest. Conclusions We obtained an estimate of local survival of little penguins breeding at Penguin Island that incorporates the permanent migration to unobservable sites and found an asymmetric dispersion towards natural nests. Implication Our conclusions suggest a need for more careful treatment of data derived from artificial sites alone, as demographic parameters might be underestimated if animals prefer natural breeding sites or if they are in greater proportion compared with artificial ones. The analytical approach presented can be applied to many biological systems, when animals might move into inaccessible or unobservable breeding sites.

scholarly journals Nest-site fidelity and breeding dispersal by Common Tailorbirds in a tropical forest

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Changzhang Feng ◽  
Canchao Yang ◽  
Wei Liang
Keyword(s):  
Nest Predation ◽  
Site Fidelity ◽  
Nest Site ◽  
Dispersal Distance ◽  
Breeding Dispersal ◽  
Nest Sites ◽  
Nest Site Fidelity ◽  
Significant Difference ◽  
Breeding Attempt ◽  
Dispersal Distances

Abstract Background Information pertaining to nest-site fidelity and breeding dispersal over successive years can help to better our understanding of how birds respond to nest predation. Methods By using mist nets and tracking the color banded individuals, we investigated nest-site fidelity and breeding dispersal by Common Tailorbirds (Orthotomus sutorius) throughout a year and between successive years in 2017–2018. Results The present study showed that Common Tailorbirds could produce up to four clutches per breeding season. When multiple broods were produced within a year, breeding pairs remained together, and the nest rebuilding rate was up to 92.2%, with only four cases (7.8%) in which birds reused their old nests. The dispersal distance between the nests during multiple breeding was found to be 10.0 ± 10.5 m, and nest-site fidelity within the same year was 90.0%. By the second year of breeding, 76.2% of individuals remained in the original breeding pairs, while for those that did switch partners, the females remained in the nest from the previous year and paired with new males. The dispersal distance between years was 26.5 ± 41.9 m, and nest-site fidelity between different years was 80.1%. There was no significant difference between within-year and between-year dispersal distances. Moreover, there was no significant difference in the dispersal distance of rebuilt nests between birds that had experienced nest predation and those that had not. Conclusions Our findings suggest that Common Tailorbirds maintain a high degree of fidelity to mates and nest-sites, and nest predation had no significant effect on territorial changes or breeding dispersal distance between each breeding attempt.

scholarly journals Social status, forest disturbance, and Barred Owls shape long-term trends in breeding dispersal distance of Northern Spotted Owls

The Condor ◽  
2019 ◽  
Vol 121 (4) ◽  
Author(s):  
Julianna M A Jenkins ◽  
Damon B Lesmeister ◽  
Eric D Forsman ◽  
Katie M Dugger ◽  
Steven H Ackers ◽  
...  
Keyword(s):  
Forest Disturbance ◽  
Dispersal Distance ◽  
Historical Study ◽  
Breeding Dispersal ◽  
Spotted Owls ◽  
Dispersal Distances ◽  
Dispersal Events ◽  
Northern Spotted Owls ◽  
Barred Owls ◽  
Over Time

Abstract Dispersal among breeding sites in territorial animals (i.e. breeding dispersal) is driven by numerous selection pressures, including competition and spatiotemporal variation in habitat quality. The scale and trend of dispersal movements over time may signal changing conditions within the population or on the landscape. We examined 2,158 breeding dispersal events from 694 male and 608 female individually marked Northern Spotted Owls (Strix occidentalis caurina) monitored over 28 yr on 7 study areas to assess the relative importance of individual (sex, experience), reproductive (annual productivity, mate availability), and environmental (forest alteration, presence of competitor) sources of variation in breeding dispersal distance. Median breeding dispersal distance was 3.17 km, with 99% of all breeding dispersal events <37 km. Mean annual dispersal distances increased by 2.43 km in Oregon and 9.40 km in Washington between 1990 and 2017, which coincided with increases in annual detections of nonnative Barred Owl (S. varia). Frequency of breeding dispersal events, both among and within individuals, also increased over time. Female owls moved farther than males (median of 3.26 and 3.10 km, respectively), and birds with less experience (territory tenure) moved farther than those with more experience. Owls that were single in the year prior to dispersal moved 13–31% farther than those paired prior to dispersal. The greatest environmental change occurring over the course of our study was the expansion of Barred Owl populations. Breeding dispersal distance was positively related to Barred Owls in the study area and disturbance within the originating territory. While it appears that social factors continue to be important drivers of breeding dispersal distance in Spotted Owls, increased competition from Barred Owls and habitat alteration have a contributing effect. Increased breeding dispersal distances should be of concern for conservation efforts and considered in population monitoring because changing dispersal behavior may lead to higher rates of mortality and/or emigration from historical study areas.

scholarly journals Animal movement drives variation in seed dispersal distance in a plant–animal network

2019 ◽  
Vol 286 (1894) ◽  
pp. 20182007 ◽  
Author(s):  
E. Rehm ◽  
E. Fricke ◽  
J. Bender ◽  
J. Savidge ◽  
H. Rogers
Keyword(s):  
Seed Dispersal ◽  
Animal Movement ◽  
Bird Species ◽  
Dispersal Distance ◽  
Dispersal Patterns ◽  
Long Distance ◽  
Gut Passage ◽  
Dispersal Distances ◽  
Seed Dispersal Distance ◽  
Passage Times

Frugivores play differing roles in shaping dispersal patterns yet seed dispersal distance is rarely quantified across entire communities. We model seed dispersal distance using gut passage times and bird movement for the majority (39 interactions) of known bird–tree interactions on the island of Saipan to highlight differences in seed dispersal distances provided by the five avian frugivores. One bird species was found to be a seed predator rather than a disperser. The remaining four avian species dispersed seeds but differences in seed dispersal distance were largely driven by interspecific variation in bird movement rather than intraspecific variation in gut passage times. The median dispersal distance was at least 56 m for all species-specific combinations, indicating all species play a role in reducing high seed mortality under the parent tree. However, one species—the Micronesian Starling—performed 94% of dispersal events greater than 500 m, suggesting this species could be a key driver of long-distance dispersal services (e.g. linking populations, colonizing new areas). Assessing variation in dispersal patterns across this network highlights key sources of variation in seed dispersal distances and suggests which empirical approaches are sufficient for modelling how seed dispersal mutualisms affect populations and communities.

Dispersal of Silver Gulls, Larus novaehollandiae Stephens, from Breeding Colonies in South Australia

1985 ◽  
Vol 12 (2) ◽  
pp. 279 ◽  
Author(s):  
JR Ottaway ◽  
R Carrick ◽  
MD Murray
Keyword(s):  
South Australia ◽  
High Status ◽  
Dispersal Patterns ◽  
North West ◽  
Significant Difference ◽  
Rubbish Dumps ◽  
The Difference ◽  
Dispersal Distances ◽  
Almost All ◽  
The City

Dispersal of Larus novaehollandiae Stephens, from 10 colonies in South Australia, was studied during 1968-8 1 by means of bands designed for identification of free-living, uncaptured individuals. Dispersal patterns were characteristic of each colony, even for three colonies which were, at most, 10 km apart. Almost all dispersal records came from the area between Adelaide and Melbourne, and within 30 km of the coast. After breeding, the majority of gulls disperse eastwards; however, dispersal from each colony was correlated with a shift of gull population into areas where food was available from human sources such as rubbish dumps. From colonies 80 km south-east of Adelaide, a major human population, the predominant winter dispersal of these gulls was north-west, into the city and suburbs. The maximum direct-line dispersal distances recorded for 95% of the 3133 resighted gulls were <458 km. The greatest direct-line distance recorded was 1430 km. Overall, there was no significant difference in the mean dispersal distances of juveniles and adults, although at distances >480 km significantly more juveniles (<2y) were seen than adults (>2y). This involved only 2.5% of the total number of birds resighted. It is suggested that older, dominant birds maintain high status at preferred feeding places, and juveniles are possibly more erratic in their movements, as they search for food. This would account for the difference in the dispersal ofjuveniles and adults from a particular colony, and also for the significantly higher proportion of juveniles found at extreme distances from their natal colonies.

Marbled salamanders (Ambystoma opacum) choose low elevation nest sites when cover availability is controlled

2006 ◽  
Vol 27 (3) ◽  
pp. 359-364 ◽  
Author(s):  
David Scott ◽  
Dean Croshaw
Keyword(s):  
Reproductive Success ◽  
Reproductive Behavior ◽  
Site Selection ◽  
Nest Site ◽  
Local Environment ◽  
Breeding Site ◽  
Nest Site Selection ◽  
Growth And Survival ◽  
Nest Sites ◽  
Selective Forces

AbstractNest site selection is an important part of adult reproductive behavior because growth and survival of young are often affected by the local environment. In terrestrially nesting marbled salamanders, nest elevation is likely important to reproductive success because it is directly related to the time of hatching. We tested the hypothesis that females choose nest sites based on elevation and its correlates by controlling the availability of nesting cover, a potentially important factor in nest site selection which often covaries with elevation. Breeding adults were confined to field enclosures in which natural nesting cover had been removed and replaced with equal proportions of artificial cover in each of three elevation zones. In four enclosures that spanned from lowest to highest areas of a wetland breeding site, females used artificial nesting cover most frequently at low elevations. These results contrast with other studies in which intermediate elevations had highest nest densities, but are consistent with a conceptual model in which opposing selective forces result in locally adapted nest site selection.

Empirical Evidence of Long-Distance Dispersal in Miscanthus sinensis and Miscanthus × giganteus

2011 ◽  
Vol 4 (1) ◽  
pp. 142-150 ◽  
Author(s):  
Lauren D. Quinn ◽  
David P. Matlaga ◽  
J. Ryan Stewart ◽  
Adam S. Davis
Keyword(s):  
Miscanthus Sinensis ◽  
High Wind ◽  
Dispersal Patterns ◽  
Long Distance ◽  
Bioenergy Grasses ◽  
Wind Speeds ◽  
Miscanthus Giganteus ◽  
Prevailing Wind Direction ◽  
Wind Events ◽  
Dispersal Distances

AbstractMany perennial bioenergy grasses have the potential to escape cultivation and invade natural areas. We quantify dispersal, a key component in invasion, for two bioenergy candidates:Miscanthus sinensis and M. × giganteus. For each species, approximately 1 × 106 caryopses dispersed anemochorously from a point source into traps placed in annuli near the source (0.5 to 5 m; 1.6 to 16.4 ft) and in arcs (10 to 400 m) in the prevailing wind direction. For both species, most caryopses (95% for M. sinensis and 77% for M. × giganteus) were captured within 50 m of the source, but a small percentage (0.2 to 3%) were captured at 300 m and 400 m. Using a maximum-likelihood approach, we evaluated the degree of support in our empirical dispersal data for competing functions to describe seed-dispersal kernels. Fat-tailed functions (lognormal, Weibull, and gamma (Γ)) fit dispersal patterns best for both species overall, but because M. sinensis dispersal distances were significantly affected by wind speed, curves were also fit separately for dispersal distances in low, moderate, and high wind events. Wind speeds shifted the M. sinensis dispersal curve from a thin-tailed exponential function at low speeds to fat-tailed lognormal functions at moderate and high wind speeds. M. sinensis caryopses traveled farther in higher wind speeds (low, 30 m; moderate, 150 m; high, 400 m). Our results demonstrate the ability of Miscanthus caryopses to travel long distances and raise important implications for potential escape and invasion of fertile Miscanthus varieties from bioenergy cultivation.

Orientation and dispersal of hatchling Blanding’s turtles (Emydoidea blandingii) from experimental nests

2009 ◽  
Vol 87 (9) ◽  
pp. 755-766 ◽  
Author(s):  
M. J. Pappas ◽  
J. D. Congdon ◽  
B. J. Brecke ◽  
J. D. Capps
Keyword(s):  
Forest Succession ◽  
Environmental Cues ◽  
The Sun ◽  
Dispersal Patterns ◽  
Sun Compass ◽  
Emydoidea Blandingii ◽  
Late Afternoon ◽  
Nest Sites ◽  
Pine Trees ◽  
Riparian Habitats

We determined initial dispersal directions of 1052 naïve and 278 experienced hatchling Blanding’s turtles (Emydoidea blandingii (Holbrook, 1838)) in experimental arenas in a variety of settings. Dispersal of naïve hatchlings was nonrandom in 7 of 10 sites. All nonrandom dispersal patterns suggested hatchlings primarily used vision to orient toward dark far horizons, particularly those associated with riparian habitats. We found no evidence that hatchlings use positive geotaxis, olfaction, humidity gradients, or scent trailing of other individuals during dispersal. Despite the lack of relationships between the changing position of the sun and relationships between nest sites and wetlands, patterns of dispersal were different for hatchlings released in the morning and late afternoon at two sites. Comparisons of the dispersal of naïve and translocated experienced hatchlings (those with previous exposure to environmental cues) suggest that hatchlings develop a sun compass within 2 days of emergence from nests. Based on all nonrandom dispersals of hatchlings at arenas, the estimated maximum perception distance of hatchlings was 325 m. In some situations, forest succession, agriculture activities, and introduction of pine trees may increase risks faced by hatchlings dispersing from nests by reducing their ability to find wetlands.

scholarly journals Almond Leaf Scorch Disease Development on Almond Branches High-Grafted on Peach Rootstock

Plant Disease ◽  
2013 ◽  
Vol 97 (2) ◽  
pp. 277-281 ◽  
Author(s):  
Tiesen Cao ◽  
Theodore M. DeJong ◽  
Bruce C. Kirkpatrick
Keyword(s):  
Xylella Fastidiosa ◽  
Average Distance ◽  
Winter Season ◽  
Growing Season ◽  
Prunus Dulcis ◽  
Leaf Scorch ◽  
Second Year ◽  
Peach Rootstocks ◽  
Almond Leaf Scorch ◽  
Made In

Development of almond leaf scorch (ALS) disease was monitored on young almond (Prunus dulcis ‘NePlus’ and ‘Peerless’) shoots produced from almond scion wood that was high-grafted on peach rootstocks (P. persica ‘Queencrest/Nemaguard’), after the almond shoots were mechanically inoculated with Xylella fastidiosa. The objective of this study was to evaluate the potential movement of X. fastidiosa through almond–peach graft unions. ALS symptoms developed on both X. fastidiosa-inoculated and uninoculated almond shoots that were high-grafted on different peach limbs of the same tree in September following inoculations with X. fastidiosa made in June and July 2002, respectively, when the average distance in peach rootstock between the two almond–peach graft unions was 30.5 cm or shorter. No ALS symptoms were observed on uninoculated almond shoots late in the growing season of the second year. The incidence of ALS-affected leaves on shoots inoculated with X. fastidiosa decreased in the second year on the inoculated shoots of Peerless as determined by the number of inoculated shoots showing ALS symptoms in 2002 versus 2003. No visible ALS symptoms were observed in NePlus late in the growing season of the second year, suggesting that survival of X. fastidiosa in NePlus was less than in Peerless. These data demonstrate that movement of X. fastidiosa through two almond–peach graft unions was possible during the year of inoculation when the peach rootstock stem distance between the two almond–peach graft unions was minimal. However, X. fastidiosa may not survive the winter season or survived so poorly as not to be able to produce ALS symptoms in the second growing season on the uninoculated shoots that previously showed ALS symptoms in the fall of the year when an adjacent shoot was inoculated. The results suggest that high-grafting almond scion wood on multiple peach rootstock limbs may provide a means to limit movement of X. fastidiosa from one almond limb to another on the same tree.

scholarly journals Family Associations in Communally Roosting Black Vultures

The Auk ◽  
1986 ◽  
Vol 103 (1) ◽  
pp. 32-41 ◽  
Author(s):  
Patricia Parker Rabenold
Keyword(s):  
Close Contact ◽  
Family Members ◽  
Breeding Dispersal ◽  
Nest Sites ◽  
Related Individuals ◽  
Family Associations

Abstract Observations of marked individuals in a partially marked population of Black Vultures (Coragyps atratus) show that immediate family members maintain close contact throughout the year. Associations between mates and between parents and offspring are primarily responsible for this. Mutual allopreening, feedings, and intercessions in fights occur almost exclusively within families. Adults known to breed within the study area (neighbors) associate more strongly than nonneighbors, although not as strongly as mates. Certain families associate preferentially with certain other families. Strength of interfamily associations is not related to distance between nest sites within the study area. I argue, therefore, that birds actively seek particular individuals as associates. Further knowledge of breeding dispersal of young of known parentage will provide clues to relatedness of highly associated neighbors. Strong associations among related individuals can help explain the use of avian communal roosts as information centers.

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