Long-term trends in abundance, phenology, and morphometrics of Little Stint Calidris minuta during autumn migration in southern Sweden, 1946–2020

THE LITTLE STINT Calidris minuta is an Arctic wader species that migrates through the Baltic Sea region towards wintering areas in North and West Africa and the Mediterranean region. We use a 75-year trapping series, comprising 4,791 Little Stints on autumn migration, from Ottenby Bird Observatory in Sweden to illustrate long-term trends in abundance, phenology, and morphometrics. Numbers of trapped juveniles dropped from median 31 (mean 74) in 1946–1999 to median 1.5 (mean 3.5) birds in 2000–2020, while the number of adults was generally low and without trends. Rolling window analyses showed that the drop in juveniles started around 1984, and from 1993 onward the median never exceeded seven juveniles/year (25 %-quantile: 0–1; 75 %-quantile: 4–55). Moreover, adult birds advanced their passage on average 0.48 days per year, passing 26 days earlier in 2020 than in 1946. Earlier migration of adults and decreased numbers of juveniles suggest low reproductive output in recent decades. Morphometric data of recaptured birds show that Little Stints on stopover at Ottenby gain fuel


Introduction
Waders form one of the most prominent groups of birds breeding on the circumpolar Arctic tundra (Cramp & Simmons 1983, Lappo et al. 2012, Keller et al. 2020).There, they utilize the short but very productive summer to raise their offspring before migrating southwards to non-breeding areas in temperate and tropical areas around the globe.One such bird is the Little Stint Calidris minuta, whose breeding range comprises the high-Arctic tundra stretching from northernmost Norway in the west to the New Siberian Islands in the east.It prefers coastal areas, but can extend into less cold regions, and occasionally to higher elevations (Cramp & Simmons 1983, Lappo et al. 2012, Keller et al. 2020).The global population is estimated at 1,500,000-1,600,000 birds, of which 48,200-76,000 pairs breed in what is considered the European part of the range (west of the Ural Mountains and including Novaya Zemlya; Keller et al. 2020).
A majority of pairs lay double clutches, with each parent taking care of one of the broods (e.g.Hildén 1983, Tulp et al. 2002).In years with favourable conditions, large numbers of offspring may be produced.However, the time available for foraging is consequently limited for parents, and nests might be abandoned if the body condition of the parents deteriorates (Tulp et al. 2002).Combined with a low breeding site fidelity (Hildén 1983, Kania & Chylarecki 1992, Tomkovich & Soloviev 1994) and environmental variation in the onset of snow melt, the double clutch strategy leads to annual variation in the number of breeding birds and their spatial distribution (Keller et al. 2020).
Birds from the European population are thought to migrate on a broad passage across the European continent in a S-SW direction (Bakken 2003, Fransson et al. 2008, Delany et al. 2009, Barlein et al. 2014), with fewer birds on the European Atlantic coast, including the British Isles (Toms 2002).The variation in locations and conditions at the Arctic breeding grounds is thought to affect the spatial variation in occurrence of Little Stints also outside the breeding season.Thus, in at a speed close to the theoretical maximum, strongly indicating that the conditions at the trapping site remain favourable for foraging waders.across the 75 years of study.Generally, the capture of southbound-migrating waders starts in late June-early July when the birds arrive, and continues at least until end of August, or in years with good numbers of juvenile waders, until September or October (very rarely even November).
Walk-in traps placed in combinations (sometimes singly) on the banks of decomposing seaweed that form along the shore, constituted the main methodology.The traps are designed to capture foraging birds and can be very efficient if conditions are good.The largest daily total is 1,207 waders and 27 days with more than 500 trapped birds have been recorded (up to year 2020).The most numerous species by far is the Dunlin, but more than 20 species are caught regularly.In the early years the traps varied somewhat in size, but from 1972 a standardized, approximately 120 cm long version has been used (two walk-in entrances, a collection chamber in each end, steel frame covered with chicken or nylon mesh; often referred to as the "Ottenby" funnel trap in the literature: Lessells & Leslie 1977, Bub 1991, Lindström et al. 2005).Since the study area is not affected by tidal water, 80-120 traps are used both day and night, and emptied every hour, except during complete darkness when wader foraging behaviour is reduced.

DATA ON RINGED BIRDS
In total, 4,791 Little Stints were trapped during autumn migration ( June-October) in 1946-2020.Of these, 228 birds were registered as adults, 3,840 as juveniles, and 723 were not specified to age.The unaged category is largely comprised of birds trapped in the first three decades.Given that 592 of unaged birds were trapped during late autumn passage (September-October) they were most likely strongly dominated by juvenile birds, as adults are rarely caught during this time (one out of 964 ringed birds in late autumn).Generally, ageing Little Stint is easy in summer and autumn based on differences in wear and colour of the plumage.While aging becomes harder when birds attain winter plumage (e.g., Prater et al. 1977), very few birds passing through Ottenby have attained winter plumage.The species is generally considered monomorphic: while females are on average slightly larger than males in structural measurements, the overlap is substantial (Niemc et al. 2018).
Bearing in mind the rapid ongoing climate change affecting the Arctic and reports of decreasing numbers of long-distance migrant wader species that breed on the tundra (Studds et al. 2017, Oudman et al. 2020), we use a time series from Ottenby Bird Observatory that covers three quarters of a century to document changes in the passage of Little Stint during the early phase of its autumn migration.We show that Little Stints display a long-term decline in numbers during autumn migration at this site in the Baltic Sea region, manifested as a steep drop in number of trapped juvenile birds during the last 20 years, and a long-term advancement of autumn passage of adults.Additionally, we provide estimates of fuel deposition rates and trends in morphometric measurements.

STUDY SITE
Ottenby Bird Observatory (56°12'N, 16°24'E) is situated on the southern point of Öland, a long and narrow island in the Baltic Sea off the coast of SE Sweden.The observatory was founded in 1946 with the aim to study bird migration through observations and bird ringing (Danielsson et al. 1947, Edelstam 1972).The site is well suited to catch migratory Arctic waders (Charadriiformes) following the East Atlantic Flyway and especially during autumn migration, passing waders use the food-rich shorelines of Öland for stopover and refuelling (e.g.Waldenström & Lindström 2001).Trapping methods and the physical environment at the observatory have remained comparatively similar Structural size measurements were available in the form of wing length measured as maximum flattened chord from carpal joint to tip of wing to the closest millimetre (1,222 birds, years 1977-2020), and total head length measured from tip of bill to back of head (with a calliper to closest mm, Green 1980) for 96 individuals (years 2007-2020).Body mass was recorded for 869 birds (years 1977 and 1986-2020), using either a spring balance or a digital scale, in most cases to 0.1 g accuracy.In the most recent years (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020), a fat score measurement on a scale from 0-9 was recorded for 113 birds (Pettersson & Hasselquist 1985, cf. Lindström 1998).

ABUNDANCE
The number of Little Stints trapped at Ottenby varied greatly between years, especially for juveniles, for which numbers ranged from 0 to 613 individuals captured in the autumn migratory season.We assessed potential changes in abundance using a rolling window approach.Using a window size of 15 years, we calculated rolling medians, as well as the 25 % and 75 % quantile for each 15-year window.To provide a quantitative estimate over the changes in abundance of juvenile and adult Little Stints over the entire study period, we additionally fit a linear regression model with abundance as response variable, and age class and years since 1945 (so years range from 1 to 75) as independent predictors.We included an interaction term between year and age to estimate the effect of year on abundance for both age classes separately, and further included a dispersion model to account for differences in variance between the abundances for adults and juveniles.We log-transformed abundance as ln(abundance + 1) to approximate a normal error distribution for the model.Individuals of unknown age were excluded from the analysis.
Estimates of trapping effort were not available for the entire 75-year period and could thus not be controlled for.Both trapping effort and trapping efficiency have always varied with the local weather situation, since long spells of warm and dry weather dry out the seaweed banks, making them less attractive for feeding waders.In contrast, passages of rain fronts and cooler weather normally attract large numbers of waders to the shores.However, the effort has been standardized in the sense that "if there are waders around, the traps should be out".Therefore, we argue that the large variation in trapping numbers between years is primarily dependent on true variations in the number of birds on stopover, and much less on trapping efforts.

PHENOLOGY
We investigated whether passage dates of Little Stints changed over the 75 years at Ottenby.We fitted a linear regression model with date of capture (as days since 1 January) as dependent variable, and number of years since the start of the trapping series (i.e.1-75), age class, and their interaction as independent covariates.As captures within a year cannot be assumed to be entirely independent, we further included the actual year of trapping as a random effect term.A visual assessment of the data suggested that variance of arrival dates differed between years and age class, so we additionally included a dispersion model to estimate variance for each age class separately, in interaction with year of record.Individuals of unknown age were excluded from the model.We assessed the distribution of residuals and decided that a normal error distribution was appropriate.

DEPOSITION RATE
We determined the mean and standard deviation (SD) for body mass, wing length, and total head length for all individuals with available measurements.We then evaluated the relationship between body mass and fat score as two indicators of body condition during passage, using a generalised linear mixed-effects model (R package lme4 v. 1.1-23; Bates et al. 2015).The model contained body mass as the dependent variable and fat score and wing length as independent covariates.We further included an interaction term between fat score and wing length, and the ringers' signatures as random effect term to account for any consistent differences between ringers.After assessment of model residuals, we determined that a normal error distribution was appropriate.We fitted two alternative models since fat score is scaled ordinally, with differences in average mass between the different scores not necessarily being consistent.In one of the alternative models, we treated fat score as a continuous predictor, whereas in the second alternative fat score was included as an ordinally ranked covariate.We here present the second alternative for interpretability but included the results for the first model in the Supplementary Information (see Data availability).
The lean body mass (LBM) of Little Stint has been estimated to 20.0 g (Pearson 1987, Lindström 1998), which fits the data presented here; only 8 birds (all juveniles) weighed less than 20 g, including one (most likely erroneous) mass of 15.3 g.We used individuals that were recaptured within the same season to estimate fuel deposition rates.In total, 23 juvenile individuals were recaptured within 1-7 days of their initial capture.We estimated fuel deposition rates using a linear mixed-effects model, with change in body mass, in grams, between the initial capture and recapture as dependent variable.We included the number of days that had passed between captures as a continuous independent predictor, and further accounted for potential differences in overall condition between years by including year as a random effect term.

ANALYSES
Descriptive statistics on variation in trapping numbers, phenology and morphometrics was extracted from the data and visualized using Microsoft Excel, IBM SPSS v. 27.0 and R v. 4.0.3(R Core Team 2020).

ABUNDANCE
The number of trapped Little Stints showed considerable annual variation (Figure 1).This was most evident for juvenile birds, where the range spanned from 0 to 631 in different years (average 51 birds per year 1946-2020).Also the number of adult birds varied between years, albeit with a lower amplitude (average 3 birds per year 1946-2020, range 0-20).Peak years with more than 100 trapped juveniles occurred in 1953, 1964, 1967, 1972, 1975, 1976, 1978, 1981, 1988, and 1990.If including the unaged birds in the juvenile category (see methods), also the years 1957 and 1959 qualified as peak years.Results of a linear model estimating the effect of year on the log-transformed annual number of captures for adult and juvenile Little Stints Calidris minuta at Ottenby, Sweden, from 1946 to 2020.The table shows the estimate, standard error (SE), and 95 % confidence intervals (CI) for the effect of the independent predictors on capture day (days since 1 January), as well as adjusted R² and total sample size.

Number of individuals
In the last 20 years, however, very few juvenile Little Stints have been caught at Ottenby (median 1.5, mean 3.5, range 0-17, years 2001-2020).The rolling window approach showed that over the period from 1955 to 1979, the median number of juveniles ranged from 74 to 91 (25 %-quantile: 15-32; 75 %-quantile: 117-229).From 1984 and onward, the 15-year median dropped rapidly to less than ten individuals, and from 1993 onward, the median never exceeded seven juveniles captured in a year (25 %-quantile: 0-1; 75 %-quantile: 4-55).Over the entire study period, the 15-year median of adults caught in a season ranged from 0 to 3 (25 %-quantile: 0-2; 75 %-quantile: 2-9; Figure 2).This impression was corroborated by the regression model fitted to the log-transformed abundance for adult and juvenile Little Stints (see Table 1, Figure 3).The estimates from the supplementary regression model indicate that the number of adults trapped across the years was more or less constant, with an effect of year on log-transformed abundance of adults of 0 (95 % confidence interval: -0.02 to 0.02), whereas it corroborated the impression of a distinct negative trend on the log-transformed abundance of juveniles with an effect size of -0.03 (95 % confidence interval: -0.05 to -0.01).

PHENOLOGY
Adult Little Stints advanced their passage at Ottenby over the 75-year observation period, with average date of capture changing from August 31 in 1946 to July 28 in 2020.This means that on average, adult birds advanced their passage through Ottenby by 0.48 days per year (see Table 2, Figures 4-5).While the model also suggested a non-zero effect of year on the mean capture date of juvenile Little Stints, this effect was rather negligible (see Table 2, Figures 4-5).The fitted model explained about 21.3% of mean capture date (marginal R²: 0.213; fixed and random effects together contribute to conditional R² of 0.579).We found that mean capture date of juveniles (estimated SD: 4.14 days) showed less variance than adults (estimated SD: 5.48 days; see Table 2).

BODY SIZE
We estimated, using simple linear regression, that adults had a mean wing length of 98.93 mm (SD: 3.4 mm; 95 % confidence interval for the mean: 98.44-99.42; Figure 6a).The wings of juvenile individuals were on average 0.84 millimetres longer, with a mean of 99.77 mm (SD: 2.8 mm; 95 % confidence interval for the mean: 99.60-99.94;Figure 6b).

BODY MASS, FAT SCORES, AND FUEL DEPOSITION
We found that wing length and fat score could explain about 44 % of the variation in body mass of captured individuals (marginal R²: 0.448; conditional R²: 0.479; see Supplementary Information).With every increase in fat score, body mass increased on average by 1.1 g (95 % confidence interval: 0.8-1.4; Figure 7), whereas wing length, as a structural measurement, had an effect of 0.4 g for every mm increase (95 % confidence interval: 0.2-0.5;see Supplementary Information).
Despite having shorter wings, adults were on average heavier than juveniles, with a mean body mass of 26.4 g (SD: 3.2 g; see Figure 8a) compared to a mean of 25.9 g among juveniles (SD: 3.8 g; see Figure 8b).This corresponds to average fuel loads of 30 % and 25 % of LBM.
We used mass gain in individuals recaptured during their stopover at Ottenby to estimate fuel deposition rates.All individuals that were weighed also at recapture were juveniles.Individuals recaptured within one or two days from the initial capture showed a change in mass ranging from -10.0 % to +4.8 % of LBM per day, but later recaptures showed consistent positive changes in body mass ranging from 1.0-14.3% of LBM per day.The largest and fastest increase in mass was 8.6 g over three days, corresponding to 14.3 % of LBM per day, in a juvenile bird in August.Using a linear mixed-effects model, we found that over period of 1-7 days after their initial capture, individuals gained about 1.44 g per day on average, or 7.2 % of LBM per day (95 % CI: 0.85-2.02g, or 4.25-10.10% of LBM).Day since capture could ex-   3 and Figure 9).

CHANGES IN ABUNDANCE AND PHENOLOGY
We found that over the 75 years of trapping of Little Stints at Ottenby, the number of juvenile Little Stints captured per year has changed from a pattern of recurrent peak years in the period 1946-1999, to low numbers without any peak years from 2000 onwards (Figure 1).This change is so dramatic that in the last two decades only 63 juvenile Little Stints were captured in total.This represents less than 1.6 % of the total number of juveniles captured during the entire trapping period from 1946 to 2020 (Figures 2-3).There are severable possible explanations for the change in juvenile abundance at Ottenby, and the important question to ask is whether this negative trend reflects true changes in breeding output of Little Stints, or if they result from changes in trapping efforts, changes in local site use of birds, or larger-scale changes in migratory routes.
While our analyses cannot account for trapping effort, the observatory aims to conduct the trapping as standardised as possible.This means that since 1972 the type and number of traps have remained constant (80-120 traps), as has the trapping period, which runs from the start of wader autumn migration in late June to at least late August, and longer in years with large number of juveniles.Even in earlier years, wader trapping was an important part of the annual routine at the station, and the peak years in Little Stint trapping numbers in the period 1946-1999 certainly represent biological peak years.Vice versa, the absence of peak years in the trapping numbers reflect low abundance at the site.This is supported by the trapping numbers of other wader species at Ottenby, which show varying trends.For instance, Dunlins (the overall most numerous Calidris species in autumn), which has a large distribution in the Arctic at lower latitudes, still show peak years also during the last 20 years including an all-time high in 2020 with 9,928 birds (average 2,968 birds per season 2001-2020).However, other investigated high-Artic waders-such as Curlew Sandpiper (Barshep et al. 2011) and Ruddy Turnstone (Helseth et al. 2005b)show trends similar to that of Little Stints.Taken together, this suggests that the methods used to trap waders are still effective, and that changes in trapping numbers reflects abundance at the site.Similarly, we are not aware of any drastic changes in the local stopover habitat.The whole trapping area is within a nature reserve and has been maintained as grazed coastal meadow during the whole study period, with only minor changes in habitat, such as slightly shifted shoreline after storm uplifts.One notable longterm change is the eutrophication of the Baltic Sea, which has affected the species composition of algae.This has led to an increase in filamentous green algae (e.g.Rönnberg & Bonsdorff 2004) that hypothetically could have affected the quality of the shore as foraging habitat for Little Stints.However, earlier studies on refuelling rate of waders at the site, together with the data on Little Stint presented here, show that birds refuel fat stores close to the theoretical maximum (Lindström 1998, 2003, Waldenström & Lindström 2001).Moreover, Little Stints normally occur in mixed species flocks dominated by Dunlins, a species that does not show the same negative trend.In our view, the habitat quality at the trapping site should be considered as suitable for Little Stints also in the period between 2000 and 2020.
The question whether large-scale shifts in migration pathways have occurred is harder to answer.Due to the broad-front migration and less westerly route used compared to other Calidris species, Little Stints do not appear in large numbers along the western coasts of Europe, and long-term count data is scarce from autumn migration throughout the continent.The exceptions to this include two long-term count surveys from western Denmark.The first is from Blåvandshuk, where Little Stints increased at an autumn migration staging site by 3.1 % per year 1963-2003, but where better binoculars and field identification skills in later decades likely also affected the long-term trend (Meltofte et al. 2006).The second study was carried out at Tipperne, where staging waders were counted 1929-2014, and in a more standardised manner from 1973.During the latter period, most autumns saw maximum numbers below 120 Little Stints at Tipperne, but in peak years, such as in  (Meltofte & Clausen 2016).However, in the long term the species shows an increase in numbers at Tipperne, with higher counts over the last 50 years than during the first decades of the study, but similarly to Blåvand it was concluded that local conditions, such as increased muddiness of the shallow flats from water level management, and better field identification skills and equipment, may have contributed to this increase (Meltofte & Clausen 2016).
The newly published European Bird Breeding Atlas indicates that the westernmost breeding range of Little Stints in northern Norway has contracted in the last decade (Keller et al. 2020), but the underlying data for the rest of the European breeding areas are too scant to draw firm conclusions.From the winter season, counts conducted in the vast coastal mudflat areas of Banc d'Arguin in Mauritania 1980-2017 show decreasing trends for Little Stints and other Calidris waders, albeit not significantly so for Little Stint (Oudman et al. 2020).Little Stints in Mauritania likely stem from the European breeding population, but negative trends in winter have been seen also in Namibia, in the south-ern part of the wintering range for the Siberian Little Stint population.This suggests a decrease in the order of 60-90 % of wintering Little Stints in two important coastal mudflats in the period 1990-2013 (Simmons et al. 2015).In the East Atlantic flyway perspective, international organisations have described the long-term trend  of Little Stints as a moderate decline, and the short-term trend (2008-2017) as a steep decline (van Roomen et al. 2018).In this perspective, using standardised trapping efforts at a staging site in autumn, the Ottenby data offers important insight into the overall trends seen in the species.
In contrast to the decrease in juveniles, the number of trapped adult Little Stints was fairly stable over the 75 years, but at a much lower level (Figures 2-3).While it is surprising that our data suggest no change in the abundance of adults, the overall lower number of adults captured per year might obscure a potential trend.Adult birds did, however, show a clear trend of progressively earlier passage during autumn migration (Figure 5), with a change in median passage of 26 days over 75 years.This is a remarkable shift given that spring passage of Little Stints in Sweden peaks as late as end of May (median 25 May, Blomqvist & Lindström 1995), indicating that the available time for breeding is short.Juvenile passage time was also advanced, but only by 9 days compared to the 1940s, and with larger uncertainty in the estimate.We are not aware of any significantly earlier spring passage, and our interpretation of the data at hand is that an increased proportion of the adults caught at Ottenby represent birds for which breeding has failed, thereby causing an earlier onset of migration.This, together with low number of juvenile Little Stints captured, suggest changes in the breeding grounds.Importantly, a similar decline in juvenile numbers has been noted for other high-Arctic species at Ottenby, such as Curlew Sandpiper, where the number of years with poor reproduction doubled in 1976-2005compared to 1946-1975(Barshep et al. 2011)), and for Ruddy Turnstone, where both juveniles and adults decreased in numbers 1947-2003 (Helseth et al. 2005b).For Curlew Sandpiper, trapping numbers of both adult and juvenile sandpipers at Ottenby have previously been correlated with lemming cycles on the tundra: in years with high lemming abundance result in reduced predation on breeding birds and increased number of juveniles in passage (Blomqvist et al. 2002).So, what are the factors that drive these changes?Currently, the Arctic faces the highest rate of climate change on the planet (e.g.Tingley & Hubert 2013), affecting large regions inhabited by Little Stints and other Arctic wader species.The effects of an increased mean temperature in the Arctic are expected to include an earlier onset of spring, potentially causing a mismatch between arrival of birds and peak food availability on the breeding grounds (e.g.van Gils et al. 2016), but could also increase frequency of extreme weather events, or affect predator-prey dynamics (Kubelka et al. 2018).At the same time, long-distance Arctic waders are also exposed to changed conditions along the migratory flyways and in the non-breeding areas, thereby potentially exacerbating effects.The loss of peak years for juvenile Little Stint and Curlew Sandpiper in the last decades at Ottenby and co-occurring advancement of autumn migration in adult birds (Barshep et al. 2011, this study) suggest negative trends in breeding output occurring over large parts of the Arctic tundra.It is hard to pinpoint the underlying reasons for this change from our data alone, but in a global dataset, Arctic breeding waders showed a threefold increase in daily nest predation rate in 1944-2016, which was associated with an increase in ambient temperatures, temperature variations in the breeding grounds, and less pro-nounced lemming cycles (Kubelka et al. 2018).Collectively, the overall lack of data and the mixed trends in the few recent studies, together with the projected large climatic changes in the Arctic, warrant a strong need for targeted breeding surveys for Little Stints and other waders in the tundra biome.

FUEL DEPOSITION
As expected, the visible deposition of fat measured in fat scores explained much of the variation of body mass in Little Stints (cf.Lindström & Piersma 1993).The average fuel load at Ottenby of adults and juveniles was around 25-30 % of LBM (approximately 25 and 26 g,respectively).This is largely within the range of what other studies have found for this species, but lower than observed for birds preparing for long-distance departures in spring (Table 4).For instance, Little Stints in Kenya seemed to leave with fuel stores of around 60 % of LBM (Pearson 1987) and Zwarts et al. (1990) found average departure fuel loads of 43 % of LBM in Mauritania.However, the autumn birds at Ottenby are a mix of recently arrived birds with depleted fuel loads, birds in the middle of their fuel deposition, and those ready for departure.A more appropriate comparison for an evaluation of fuel loads of Little Stints departing from Ottenby may be to look at the highest fuel loads  (Lindström 2003).
For a species that is heading for wintering grounds in Africa, Ottenby is still at the beginning of a long journey.In a westward expedition along the Arctic coast from the Laptev Sea to the Barent Sea, Little Stints showed an increase in mass westwards, indicating that birds in the western range prepared for a longer migration leg (Lindström 1998).Highest mean body mass was recorded at the Kola Peninsula (31 August), with 28.0 g, corresponding to fat stores of 40 % of LBM, deemed sufficient to reach southern Baltic stopover sites, such as Ottenby (Lindström 1998).

FIGURE 2 .
FIGURE 2. The results from the rolling window approach over the number of adult (left panel) and juvenile (right panel) Little Stints Calidris minuta captured at Ottenby Bird Observatory over the study period 1946-2020.The line shows the 15-year median and the shaded area shows the interquartile range of individuals trapped for the same period.Estimates at the lower and upper range of years are based on at least 10 years of data, and the first and last five years were excluded.Points show the raw data, i.e., the actual number of birds trapped during the respective year.-Resultaten av en tidsserieanalys med ett rullande fönster av 15-årsmedianer över fångstsiffor av småsnäppor Calidris minuta vid Ottenby fågelstation 1946-2020 (adulta fåglar i den vänstra panelen, ungfåglar i den högra panelen).Linjen visar 15-årsmedianen och den skuggade ytan interkvartilvärdena.Estimaten för början och slutet av tidsserien baseras på 10 års data, och de första och sista 5 årens data är exkluderade.Punkterna visar rådata, det vill säga antalet fångade fåglar varje år.

TABLE 2 .
Results Nakagawa et al. 2017ning change in body mass between initial capture and recapture of juvenile Little Stints Calidris minuta at Ottenby, as a function of days between captures.The table shows the estimate and 95 % confidence intervals (CI) for the effect of days between captures on change in body mass, as well the variance and random intercept variance for the random effect of trapping year.The table further reports marginal and conditional R² (according toNakagawa et al. 2017) and total sample size.-Resultatenfrån modellen som förklarar juvenila småsnäppors Calidris minuta förändring i kroppsvikt mellan första fångst och återfångst vid Ottenby, som en funktion av antalet dagar mellan fångsttillfällena.Tabellen visar skattning och 95 % konfidensintervall (CI) för effekten som antal dagar mellan fångsttillfällen har på kroppsviktens förändring samt varians och slumpmässig skärningspunktsvarians för den slumpmässiga effekten av fångstår.Vidare rapporterar tabellen marginella och betingade R²-värden samt provstorlek.

TABLE 4 .
Body mass (g ) of Little Stints Calidris minuta from various parts of the non-breeding season.-SmåsnäppansCalidris minuta kroppsvikt ( g) under olika delar av årscykeln utanför häckningssäsongen.When considering only individuals with the highest fuel loads, Little Stints at Ottenby have a body mass that is comparable to other places.Indeed, putting on very high fuel loads makes sense at a place where the fuel deposition rate is very high, such as at Ottenby, where Little Stints had fuel deposition rates close to the expected maximum