Comparing fruiting phenology across two historical datasets: Thoreau’s observations and herbarium specimens

Background and AimsFruiting remains under-represented in long-term phenology records, relative to leaf and flower phenology. Herbarium specimens and historical field notes can fill this gap, but selecting and synthesizing these records for modern-day comparison requires an understanding of whether different historical data sources contain similar information, and whether similar, but not equivalent, fruiting metrics are comparable with one another.MethodsFor 67 fleshy-fruited plant species, we compared observations of fruiting phenology made by Henry David Thoreau in Concord, Massachusetts (1850s), with phenology data gathered from herbarium specimens collected across New England (mid-1800s to 2000s). To identify whether fruiting times and the order of fruiting among species are similar between datasets, we compared dates of first, peak and last observed fruiting (recorded by Thoreau), and earliest, mean and latest specimen (collected from herbarium records), as well as fruiting durations.Key ResultsOn average, earliest herbarium specimen dates were earlier than first fruiting dates observed by Thoreau; mean specimen dates were similar to Thoreau’s peak fruiting dates; latest specimen dates were later than Thoreau’s last fruiting dates; and durations of fruiting captured by herbarium specimens were longer than durations of fruiting observed by Thoreau. All metrics of fruiting phenology except duration were significantly, positively correlated within (r: 0.69–0.88) and between (r: 0.59–0.85) datasets.ConclusionsStrong correlations in fruiting phenology between Thoreau’s observations and data from herbaria suggest that field and herbarium methods capture similar broad-scale phenological information, including relative fruiting times among plant species in New England. Differences in the timing of first, last and duration of fruiting suggest that historical datasets collected with different methods, scales and metrics may not be comparable when exact timing is important. Researchers should strongly consider matching methodology when selecting historical records of fruiting phenology for present-day comparisons.     

The phenology of spring bird migration to north Norway

Capsule There was no evidence of a long-term trend in arrival dates of spring migrants over the last 20 years in north Norway.

Aims To investigate the effect of climate on the timing of spring arrival of many species at their northern limit of breeding distribution and to seek evidence of any long-term trend.

Methods Observations of spring arrivals of 71 species into Troms, north Norway (69–70°N) between 1970 and 2000 by members of the local branch of the Norwegian Ornithological Society were analysed and related to available weather parameters.

Results The first migrants arrive in mid-March when air temperatures are still below 0°C and c. 1 m of snow is on the ground, with the main influx in late April and throughout May. By then much of the snow has melted and temperatures are c. 5°C. There was no evidence of a long-term trend in the median dates of arrival across 31 species in Troms between 1980 and 2000. However among 14 species for which detailed data exist in a limited area around Tromsø, the Golden Plover Pluvialis apricaria showed a significant trend towards an earlier arrival and the Willow Warbler Phylloscopus trochilus showed the opposite. Spring migration tended to be advanced during warm springs, and seven of the above subsets of 14 species showed significant negative correlations between their arrival dates and temperature. One showed a positive correlation.

Conclusion The data collected to date are a good baseline for future studies of the effects of climate change on migration phenology.     

Leaving on migration: estimating departure dates of Barn Swallows Hirundo rustica from summer roosts using a capture–mark–recapture approach

Capsule Capture–mark–recapture data can be used to predict departure dates of Barn Swallows Hirundo rustica from summer roosts.

Aims To investigate how long Barn Swallows remain at their breeding grounds before migration by estimating departure dates.

Methods A capture–mark–recapture approach was applied to an extensive data set (65?303 ringed and 710 recaptured birds) from two summer roosts. Multiple-day constancy models were used to estimate apparent survival, which was subsequently translated to residence time.

Results The longest intervals between ringing and recapturing were between 66 and 67 days; estimated mean minimum durations were between 16.3 and 18.5 days. Apparent survival was high over most of the summer, indicating that there is little emigration during this period and was followed by a sharp departure-related decline in late August and September. Expected residence time, derived from apparent survival estimates, declined linearly from about 80 days in early July to less than 10 days in September. Estimated departure dates were highly consistent between years and occurred in late September.

Conclusions Barn Swallows stay much longer at post-breeding roost sites than is necessary to build up their fat reserves for migration. We suggest that the birds are likely to derive a number of benefits from such a prolonged stay that are not directly related to preparation for migration; for example, minimizing predation risk by foraging in familiar areas, and gathering information on the quality of future breeding sites.     

Stoneworts of Coll and Tiree

Background: Since phenology is a good bio-indicator of temperature the latter is often used in phenological analyses. However, whilst meteorological data are difficult to interpolate from point measurements at the desired resolution, region-wide digital data, e.g. elevation models or land cover data, are usually readily available.

Aims: The potential of environmental variables, other than meteorological data, to create a bioclimatic classification of landscapes at the mesoscale was tested by the joint use of spatial data and the flowering dates of Forsythia suspensa at 70 phenological stations in southern Bavaria, Germany.

Methods: A linear discriminant analysis was carried out to identify relevant land use variables that were correlated with phenology and, using these results, to regionalise the observed flowering dates within the framework of a Geographic Information System.

Results: The generated map represented dates of onset at the regional scale, mostly influenced by the extent of impervious (hard, sealed) surfaces and forest, altitude and distance to urban areas. Thus, we overcame restrictions resulting from the difficulties of spatially interpolating available climatological data, and from the limited number of phenological datasets.

Conclusions: We demonstrated that the selected variables were capable of adequately modelling regional bioclimatic zonation, and that phenology was a useful proxy of regional climate variation arising from both natural and anthropogenic factors.     

Some Neglected Western Ozark Radiocarbon Dates

Abstract

Thirteen radiocarbon dates from mound and habitation sites, and from late Quaternary spring deposits in the western Ozarks of Missouri are published here, several of them for the first time.     

A Reexamination of Roper’S Trend-Surface Analysis of Central Plains Radiocarbon Dates

Abstract

A reexamination of Roper’s (1976) trend-surface analysis of Central Plains radiocarbon dates indicates that 1) a nonlinear trend in the data was not recognized, and 2) the dates of the trend-surface contours given in her map of the Central Plains are in error. A revised trend-surface model is presented which better describes the site data and more closely agrees with the Central Plains cultural sequence.     

Isochronous Interpretation of Some C14 Datesa Technique for Temporal and Regional Studies

Abstract

Isochronous maps contoured to values of absolute dates for two Paleo-Indian complexes provide the basis for extending some interpretations of culture which are derived from temporal data. Place and time of origin can be determined, if not with exactness, at least with a greater degree of accuracy through graphically interpreted cultural associated dates. Mere concentrations of sites and oldest dates are not always sufficient criteria for determining the probable center of development of cultures. Direction, distance and rate of diffusion or migration are read directly from the graphic presentation of the data. From a careful extrapolation of contoured values the probable contemporaneity of cultures such as Folsom and Clovis is demonstrable. Finally, a considerable degree of confidence can be placed in information derived by cautious extrapolation and interpolation of contoured values of isochronous maps.     

On The Significance of Additional Radiocarbon Dates from Bonfire Shelter,Texas

Abstract

Two hitherto unreported dates from charcoal samples associated with remains attributed to a Paleo-Indian bison kill at this site are provided. These dates further substantiate a minimal antiquity of ca. 10,000 years for the deposit and, by inference, give evidence of the use of a “bison jump” technique of hunting at this early time period. Definitional problems, differing views on the antiquity, basic comparability of cited examples, and temporal continuity of this mode of mass killing are briefly discussed. Some suggestions are made as to the cultural implications made probable by acceptance of an early date for this practice.     

A Tentative Radiocarbon Chronology for the Middle Missouri Tradition

Abstract

Chronology has long been a major concern of researchers in the Middle Missouri Subarea. However, the paucity of radiocarbon dates, as well as the general lack of multiple dates for many components, has hampered comprehensive assessment and interpretation of culture-historical sequences. A large number of radiocarbon dates pertaining to the Middle Missouri Tradition has become available over the last several years, and presently at least 124 dates are available from both published and unpublished sources for 36 components of the tradition. Dates for each radiocarbon-dated Middle Missouri Tradition component in the Big Bend, Bad-Cheyenne, Cannonball, and Knife-Heart Regions – a total of 111 dates for 33 components – are assessed and averaged according to techniques recently advanced by Bruce Rippeteau and Austin Long. Tentative occupational sequences for each of these regions are offered and problems with specific date series are discussed. Dates for components in the Grand-Moreau Region and the James River valley are also discussed, but are not fitted into sequence. Lehmer’s earlier postulation of a gap in the Bad-Cheyenne sequence at about A.D. 1300 is supported by this analysis, and the presence of a similar hiatus is suggested for the Cannonball Region.     

Dramatic changes in the return date of Guillemots Uria aalge to colonies in Shetland, 1962–2005

Capsule Changes in return date coincided with marked changes in population size that probably resulted in fluctuating competition for nest-sites.

Aims To document the changes in return dates over a 44-year period and to identify the factors associated with these changes.

Methods We compared changes in return date at Shetland colonies with those for the Isle of May, southeast Scotland, and with the available information on population size, the abundance of some fish species eaten by Common Guillemots and large-scale changes in the oceanography and climate of the eastern Atlantic as reflected by the winter index of the North Atlantic Oscillation (NAO).

Results Common Guillemots normally return to colonies in Shetland in late winter. However, during the 1960s return dates became gradually earlier with birds present from early October. Autumn return remained the norm for about ten years after which return dates gradually reverted back to late winter. In contrast, Common Guillemots on the Isle of May, 400 km south of Shetland, showed no marked shift, returning in October each year. There was a strong negative correlation between date of return of Shetland birds and population size, whereas on the Isle of May birds came back earlier when there was a large positive winter NAO index. There was no convincing evidence that changes in wintering areas or fish abundance influenced when birds returned to the colonies, although the fish data may not have been collected on the correct spatial scale.

Conclusion Competition for high quality nest-sites is the most likely reason for Common Guillemots returning to the colonies during the autumn and winter.     

A Local Sequence For Mill Creek Sites In The Little Sioux River Valley

Abstract

Mill Creek ceramics from northwest Iowa are used to derive a sequence of occupations for sites along the Little Sioux River and its tributaries. Previous typologies and attempts at seriation of sites are examined and tested. The methods employed in this study are evaluated, and the resulting seriation is cross-checked with stratigraphic evidence and a series of radiocarbon dates.     

Dendrochronology In Plains Prehistory: An Assessment

Abstract

Chronologies and climatological interpretations based upon annual growth rings of trees have been available to prehistorians within the Plains for more than half a century. Until the advent of radiocarbon dating, tree rings provided the only “absolute” chronology for most archeological complexes and subsequently, continued as an important adjunct to radiometric methods. Nonetheless, the validity of tree ring dates in the Plains must be questioned. Continuity of research has been lacking, there have been serious methodological problems, and the provenience of many specimens is in doubt. Moreover, there are significant conflicts between tree ring and recent radiocarbon dates.     

An annotated bibliography of recent significant publications on indigo and related compounds

Abstract

This bibliography lists and provides commentary on publications describing the history, preparation, chemistry and applications of indigo and related dyes. The dates of the publications are mostly, but not exclusively, later than the previously published indigo bibliography. Note that commentary by the author is placed after the bibliographic information and is set in italics.     

Radiocarbon dating of peat macrofossils in the Cairngorm Mountains,Scotland

Summary

Radiocarbon dates for tree stumps at another three sites in the Cairngorm Mountains are presented. These are considered along with a previous set (Pears, 1969) and the evidence they provide for determining altitudinal limits of forest growth in the Flandrian Period is discussed. They support earlier tentative conclusions that the topographical factor and local site hydrology are the key factors in interpreting the macrofossil pattern.     

An Assessment Of The Radiocarbon Dates For The Helb Site, 39Ca208, South Dakota

Abstract

Eleven radiocarbon dates from the Helb site (39CA208) in north-central South Dakota are presented and interpreted by techniques recently advanced by other authors. The results appear to substantiate two occupations of the site, one in the mid-eleventh century A.D. and anotherin the early or middle portion of the sixteenth century A.D.     

The changing bird phenology of Mid Deeside,Scotland 1974–2010

Capsule Marked changes were observed in the spring phenology of birds and were more apparent in residents and short‐distance migrants than in trans‐Mediterranean migrants.

Aims To examine changes in first songs and arrivals of birds in northeast Scotland.

Methods First song or first observations of 38 species were recorded between 1974 and 2010. Trends through time, and relationships with regional variation in temperature, were both examined.

Results There was a strong tendency for first song/first arrival dates to advance, with the average change being an advance of 25 days over the 37 years of study (or 0.7 days per year). Change was greater in the dates of first song of resident species than in the first detection of short‐distance and trans‐Mediterranean migrants. Relationships with temperature were apparent, but were significant for fewer than half of the species.

Conclusion Bird species vary greatly in their phenological response to climate warming. The recent decade of sustained higher spring temperatures has enabled greater detection of change in long‐term time series, and milder winters (except 2009/10) have also increased the incidence of wintering in short‐distance migrants.     

Notes On the Crow-Hidatsa Schism

Abstract

Three lines of evidence bearing on the Crow-Hidatsa separation provide different dates for that separation, but dates which are consistent with the following generalizations: (1) The Crow began to diverge linguistically from the various Hidatsa groups no less than five centuries ago, and perhaps even earlier. (2) The Crow movement onto the Northwestern Plains was accomplished gradually, perhaps by band-by-band movement, rather than as one precipitous migration away from the Hidatsa. (3) Archaeological evidence from sites of the Mandan/Hidatsa continuum in the Missouri Valley suggest that the Hagen site, at least, probably dates at about A.D. 1675 – although alternative explanations for related sites suggest that the Crow moved into the Northwestern Plains several centuries earlier. (4) Ethnohistorical data suggest that the Crow separation dates from the mid-1700s. Rather than dating the initial separation of the two groups, the ethnohistorical data probably reflect the final severing of ties with the Hidatsa – a separation made final by the adoption of the horse.     

Testing the Modified Initial Middle Missouri Variant

Abstract

Taxa in the Middle Missouri subarea are differentiated largely on the basis of cultural content and time; thus, the creation of a new taxon (the Modified Initial Middle Missouri Variant of the Middle Missouri Tradition) implies change within the Initial Middle Missouri Variant - change which is implied but not documented. The objective of the present study is to examine the validity of the new taxon. The analysis relies primarily on ceramics, supplemented by a new series of radiocarbon dates. The investigation failed to support the hypothesized ceramic tradition change, and the radiocarbon dates suggest these sites do not fit the Modified Initial Middle Missouri time period. This study concludes the Modified Initial Middle Missouri Variant is not a valid taxon.     

Crow Pottery In Northern Wyoming

Abstract

Mandan Tradition ceramics in northern Wyoming and adjacent areas of Montana and South Dakota have been attributed to the Crow Indians. A decade of excavation and collection of this pottery suggests it may have first appeared around the beginning of the 16th Century and lasted well into the 18th Century although these dates are tentative. Several restorable vessels provide a better knowledge of the range and shapes and design elements.     

Determining Great Bittern Botaurus stellaris laying date from egg and chick biometrics

Capsule Great Bittern breeding phenology can be estimated from egg and chick biometrics.

Aims To estimate egg or chick ages in order to back-calculate egg-laying dates.

Methods Bittern nests were searched for in six French and three Belarussian sites between 1999 and 2004. Eggs and chicks were measured at each visit. By using a subsample of nests with known egg-laying (or hatching) dates, regression equations are determined using egg density and tarsus length in order to estimate, respectively, egg and chick ages. Additionally in Belarus, the ‘water test’ was used to estimate the incubation stage of the clutch.

Results A total of 141 Bittern nests were found. Egg density decreased linearly from 1.063 at laying to 0.915 the day before hatching. A regression equation therefore allows estimation of egg age from its density. A scale was also constructed to estimate egg age from its position in water, and the accuracy of the two methods is compared. Chick growth rates were similar between the two countries. Before the age of 25 days, chicks are best aged by tarsus length compared to other measurements (weight, bill length). No data were available after that age because chicks were no longer found on nests.

Conclusions Egg-laying date can be estimated to within ±3 days using egg density, and to within ±5 days, using the ‘water test’. Tarsus length can be used until the age of 25 days to age chicks to within ±2 days. These simple measurements provide efficient and accurate methods to record the breeding calendar of this endangered species.