Winter Site Fidelity Research Articles

DIET AND NUTRITION OF NORTHERN PINTAILS WINTERING ALONG THE SOUTHERN COAST OF TEXAS

Abstract Most northern pintails (Anas acuta; hereafter pintails) in the Central Flyway winter within the Gulf Coast and adjacent rice prairies of Texas, USA. However, wintering habitat has declined in this region as a result of decreased rice production and changes in land use. Because pintails exhibit high winter site fidelity, more pintails are likely to rely on adjacent coastal habitats during winter as freshwater habitats along the Texas coast disappear. However, few studies have investigated the diet of pintails in estuarine environments. We estimated the composition and quality of the diet of pintails wintering along the lower Texas coast, and we compared our estimates to those for pintails in freshwater habitats. Proximate composition and true metabolizable energy (TME) were estimated for 4 foods in the diet of 253 pintails collected along the lower Texas coast during October–February 1997–1998 and 1998–1999. Shoalgrass (Halodule wrightii) rhizomes, wigeongrass (Ruppia maritima) seeds, dwarf surf c...

Long-term satellite tracking sheds light upon variable migration strategies of White Storks (Ciconia ciconia)

During investigations on the migration of 120 individual White Storks by means of satellite tracking, four birds were tracked into their winter quarters several times, one bird on nine successive journeys. These storks did not exhibit strong winter-site fidelity, but instead occupied somewhat different winter quarters from one year to the next, probably depending on the food supply.

Winter Site Fidelity of Prairie Warblers in the Dominican Republic

AbstractWintering Prairie Warblers (Dendroica discolor) were studied in pine forest, desert thorn scrub, and desert wash habitats of the Sierra de Bahoruco, Dominican Republic from October–April 1996–1998 and January–February 1999. We used mist netting, color banding, and extensive resighting of color-banded birds to quantify habitat-specific demographies, site fidelity, and fitness indices. Males predominated early in the season in pine habitat while females predominated in the desert. Sex ratios were more equal through the drier months of late winter although females continued to be more frequent in the desert. Adult birds predominated throughout all habitats and time periods. Nonterritorial wanderers were far more common in desert habitats than in pine forest, and females predominated among these wanderers. Site persistence was moderately high, but variable between habitats and time periods, and was significantly lower in the drier months in thorn scrub than it was in the desert wash or pine forest. Annual return rates were generally high and did not vary significantly among years. Birds showed significant declines in pectoral-muscle-mass scores in both of the desert habitats but not in the pine forest. Data presented here emphasize the importance of dry-season events and habitat heterogeneity in the winter ecology of migratory birds.Fidelidad al Territorio Invernal de Dendroica discolor en la República DominicanaResumen. En los meses de octubre a abril de 1996 a 1998 y enero y febrero de 1999, investigamos a Dendroica discolor en el bosque de pino, en los matorrales del desierto y en el arroyo seco de desierto en la Sierra de Bahoruco, República Dominicana. Para llevar a cabo esto, se utilizaron redes ornitológicas y anillos colorados. Se realizó una revisión extensiva de las aves anilladas para cuantificar la demografía en los tres hábitats, la fidelidad al territorio invernal, y los índices de aptitud (“fitness”). Al comenzar el invierno, los machos predominaron en el bosque de pino mientras que las hembras lo hicieron en el desierto. La proporción entre los machos y las hembras mantuvo una mayor igualidad entre los sexos en los meses más secos del invierno, aunque hay que considerar que las hembras predominaban en el desierto. Se observó que las aves adultas predominaban en los tres hábitats durante todo el período investigado. Las aves sin territorio eran más comunes en el desierto y eran mayormente hembras. La fidelidad al lugar fue moderadamente alta pero variable entre los hábitats y los períodos y fue significativamente más baja en los meses secos en los matorrales del desierto que en los arroyos secos y los bosques de pino. La tasa anual de retorno de esta especie fue generalmente alta y no varió significativamente entre años. La masa de los músculos pectorales bajó significativamente en las aves que se encontraban en los matorrales del desierto y en el arroyo seco pero no en los bosques de pino. Los datos mencionados aquí acentúan la importancia de eventos que ocurren en la época seca del período invernal y de la heterogenidad del hábitat en la ecología invernal de las aves migratorias.

Winter Site Fidelity of Nearctic Migrants in Shade Coffee Plantations of Different Sizes in the Dominican Republic

Winter Site Fidelity of Nearctic Migrants in Shade Coffee Plantations of Different Sizes in the Dominican Republic

Winter Site Fidelity of Nearctic Migrants in Shade Coffee Plantations of Different Sizes in the Dominican Republic

Abstract We studied three Nearctic migrant species (American Redstart [Setophaga ruticilla], AMRE; Black-and-white Warbler [Mniotilta varia], BAWW; Black-throated Blue Warbler [Dendroica caerulescens ], BTBW) wintering in 14 isolated shade coffee plantations (0.1 to 8.7 ha) in the Dominican Republic to determine if site fidelity was comparable to that in tropical forests and if it decreased with plantation size. Site fidelity was measured as the percentage of wandering birds captured in mist nets, as overwinter site persistence of uniquely marked birds observed on the same sites (November to March), and as annual return of marked individuals to previously occupied sites (January to January). The percentages of wanderers in net captures were mostly lower than values reported for natural forests (AMRE 21%, BAWW 12%, BTBW 41%) and did not vary with plantation size. Overwinter site persistence (AMRE 65%, BAWW 65%, BTBW 76%) and annual return (AMRE 34%, BAWW 40%, BTBW 31%) in the plantations fell within the range of values reported for natural forests. Overwinter site persistence decreased with plantation size only in AMRE, although BAWW showed lower persistence in small plantations from early to midwinter. Annual return decreased with plantation size only in AMRE. Despite diminished site fidelity in small plantations, these birds showed some fidelity to small plantations, many of which were smaller than the mean size of winter home ranges.

Winter site-fidelity and survival of Redshank Tringa totanus at Cardiff, south Wales

The site-fidelity of adult Redshank Tringa totanus was investigated using colour-ringing and radiotracking at Cardiff Bay, a wintering site in south Wales, in 1996/97 and 1997/98. Between 7 and 20% of colour-ringed adults were seen away from the bay in winter, although only at a distance of 4 km. Radiotracking also suggested that adults were largely faithful either to the bay or to this neighbouring site. Return rates of 89% and 83% were estimated over two successive summers, indicating site-fidelity between winters. Survival rates of 91% and 100% were estimated over the two preceding (four-month) winter periods. Annual survival rates, calculated as the product of the winter survival and over-summer return rates, were therefore 81% and 83%. These estimates are comparable to those previously obtained for Redshank, in studies both on breeding and wintering grounds. Analyses of ring recovery data from throughout the UK complemented the colour-ringing and radiotracking studies in showing that the majority of Redshank are site-faithful both within and between winters. Ring recovery analyses also indicated that first-year Redshank had similar recovery patterns to adults.

Survival and winter site-fidelity of Turnstones Arenaria interpres and Purple Sandpipers Calidris maritima in northeast England

The winter site-fidelity and annual survival of Turnstones Arenaria interpres and Purple Sandpipers Calidris maritima was investigated at Hartlepool, Cleveland using samples of individually colour-ringed birds. All colour-ringed Purple Sandpipers and a high proportion of colour-ringed Turnstones present at the start of winter were resident in the study area throughout the winter. All Purple Sandpipers and a high proportion of Turnstones (81–88%) survived the winter. Reasons for the high winter survival rates of both species in comparison with other waders are discussed. Most Turnstones (83–88%) survived between spring and autumn and came back to Hartlepool, usually to the same feeding area. A lower proportion of Purple Sandpipers (57–77%) survived through the summer to return to Hartlepool, particularly in 1993; some returned to winter elsewhere. Annual survival and summer return rates of both species are discussed in comparison to those reported in previous studies.

Wintering site fidelity and movement patterns of Western Sandpipers Calidris mauri in the San Francisco Bay estuary

Western Sandpipers Calidris mauri are the most numerous shorebird species in the San Francisco Bay estuary during winter. A sample of 106 Western Sandpipers was captured in mist nets and radio‐marked with 1‐g transmitters to examine their wintering site fidelity and movements. Differences in distances moved, home range extent and core area size were examined by age, sex, season, site, time of day and tide. All birds remained in the south San Francisco Bay region during winter and exhibited strong site fidelity, with a mean home range of 22.0 km2 or only 8% of the study area. First‐year birds had larger home ranges (26.6 ± 3.6 km2) than adults (17.2 ± 2.5 km2) in winter, but home range sizes of males and females were not significantly different in any period. Home range sizes were similar between seasons, but core areas were smaller in spring (6.3 ± 1.2 km2) than in early (9.6 ± 4.0 km2) or late (11.6 ± 1.6 km2) winter. Movements and home range size were similar for radio‐marked birds located during day and night. The high degree of regional and local site fidelity demonstrated that the mixture of natural mud fiats and artificial salt ponds in southern San Francisco Bay provided sufficient resources for large wintering populations of Western Sandpipers.

Social Unit of the Alpine Accentor Prunella collaris in the Non-breeding Season

The breeding unit of the Alpine Accentor Prunella collaris is a territorial group consisting of seven unrelated members. Within the group, cooperative polygynandry is common; females copulate with several male members and the males help to feed the chicks of the several females with whom they have copulated. Do Alpine Accentors, like typical cooperative breeders, maintain the membership of the group throughout the year? The social unit in winter and the wintering ecology were studied at Ashio in 1989-95, Yoshino in 1990-93 and Misaka-Pass in 1992-95. At each site, one or two (total of four) individuals banded at a breeding site, Mt. Norikura, wintered. They exhibited wintering site fidelity within seasons and between years. They were recorded singly or in flocks with less than ten unhanded birds. The unhanded birds were not members of their breeding group, which means that the breeding group was broken' up in winter. We also found no evidence of extended bonds between parents and their offspring in winter flocks. Flocks were less cohesive and their membership often changed day by day. Linear dominance hierarchies were observed within a flock. Individual activities were concentrated in particular areas, but they frequently associated with other conspecifics without aggression. Wintering individuals spent, on average, 78.1% and 17.3% of their total activity foraging and perching, respectively. Information at other wintering sites also shows that Alpine Accentors live in less cohesive small flocks but can readily switch from solitary living to flocking. We conclude that the breeding group and the winter flock in Alpine Accentors are independent of each other because there was no evidence that individual associations (group composition and family bonds) were maintained between breeding and, wintering sites.

Do all Blackcaps Sylvia atricapilla show winter site fidelity?

Fidelity to previous wintering areas (i.e. site fidelity) has important ecological and evolutionary implications. However, since the percentage of recaptures of ringed birds at the same wintering area in subsequent years does not allow the estimation of the proportion of birds alive that exhibit site fidelity, previous studies on different passerine species have failed to show the true extent of this site fidelity. Here we use a recent approach, based on the comparison of survival rate estimates from capture‐recapture data at single field stations with recovery data from a much larger area. The idea is to determine the proportion of birds still alive that return to the area. The study was carried out on the Blackcap Sylvia atricapilla, comparing the capture‐recapture data of two field stations (Pilas [SW] and Tiana [NE]) situated 1000 km apart in Spain with the complete winter recovery data of the Spanish Ringing Office. Totals of 1936 and 3976 Blackcaps were ringed at Pilas (1981–1986) and Tiana (1975–1986), respectively, and the numbers of recaptures in subsequent winters were 94 and 34. The pooled annual survival rate estimation based on the two sites is 0.40 (s.e. = 0.05). The annual survival rate estimated from the Spanish ringing recovery data was 0.48 (s.e. = 0.08), which is not significantly different. We can conclude, therefore, that migrant Blackcaps in Spain, if alive, tend to return year after year to the previous wintering site.

Spatial and social behaviour of Nearctic warblers wintering in Venezuelan mangroves

The winter ecology of the Northern Waterthrush (Seiurus noveboracensis), the Prothonotary Warbler (Protonotaria citrea), and the American Redstart (Setophaga ruticilla) was studied in tropical mangroves of northeastern Venezuela. The birds' spatial and social behaviours were assessed through intensive mist-netting and observation sessions over two complete annual cycles. In all three species, transients corresponded to half of the migrant populations. Although many birds were observed more than once within a range of 50 m, most of them also moved considerably. Home ranges of individuals overlapped greatly in both Northern Waterthrushes and Prothonotary Warblers. Birds stayed in the mangroves for an average 2-month period, irrespective of their date of arrival, whereas new individuals were observed during most of the wintering period. Winter site fidelity characterized both transient and site-attached individuals. Although many birds showed some kind of site attachment, none of the three species can be considered territorial in the mangroves.

Year to year recurrence and site‐fidelity of blackcapssylvia atricapillaand robinserithacus rubeculain a mediterranean wintering area

Capture‐recapture data of 1985 Blackcap and 218 Robin migrants ringed during 6 winters were analysed to describe the winter site fidelity and the year to year recurrence at Pilas, Seville, Spain. A higher percentage of Robins (31.6%) than Blackcaps (18.7%) were recaptured. Most of the recaptures were recorded within the same winter of ringing and especially within different months of the same winter. On average, a higher percentage of Robins (22.4%) than Blackcaps (11.3%) were retrapped within the same winter. These percentages varied significantly among years in Blackcaps but not in Robins. Although both species were ringed between the end of September and March, recaptures were only recorded between November and February which suggests that this is the real period of winter residency. The percentage of recoveries subsequent to the winter of ringing diminished with no statistical variation among species or periods. The longest period between the first and last capture was higher in Blackcaps (Syr) than i...

Facultative Extension of Fall Migration by Yellow-Rumped Warblers (Dendroica coronata)

Abstract Many nocturnally migrating birds show at least some degree of winter site fidelity. Laboratory tests of nocturnal activity, or Zugunruhe patterns, and displacement experiments indicate that migratory distances may be under endogenous control. Yellow-rumped Warblers (Dendroica coronata auduboni) displayed a southerly nocturnal orientation well into winter months, past the conventional migratory period. Additionally, population shifts between highly isolated, limited, desert riparian habitats reflected a facultative migration from north to south. The magnitude of movement was correlated with food-resource abundance, which was dependent on climatic conditions. This suggests that the birds maintain a physiological state that enables them to winter as far north as possible but allows for a correctly oriented movement if conditions become unfavorable. Our results indicate considerable plasticity in what is generally considered a more rigidly fixed process.

Decartes and the barometer

Between 1984 and 2002, a total of 7643 Bluethroats were ringed and 1054 of these were re-captured at the International Birding and Research Center (IBRCE) in Eilat, Israel (29°33′N, 34°57′E). The autumn migration of Bluethroat begins in September and ends in early December (median 01-Nov). The spring migration starts in early March and continues till May (median 21-Mar). Wintering Bluethroats arrive during October and November and stay in Eilat until March and April. The Bluethroats remain at the winter quarters for up to 4 months, though some individuals could linger for as long as more than 5 months. The majority of the wintering population was males (65.3%) and adult birds (66.1%), the sex ratio during winter (65:35) did not differ significantly from the sex ratio during autumn migration (60:40). The ratio between young and adult birds at Eilat during winter (66:34) differed significantly from the autumn migration (75:25). Wintering site fidelity for six seasons (consecutive autumn through spring) from 1996 to 2001 was 1.8%. Wintering site fidelity of Bluethroats when compared between birds that winter for the second and third season shows a recovery rate of 37.1%.