Natural and human-made nesting habitat use by Bank Swallow (Riparia riparia) in Canada

Bank Swallow (Riparia riparia) is a Threatened migratory bird in Canada that nests colonially in burrows excavated in both human-made and natural banks. Until the mid-20th century, nest record cards reported 60% of Bank Swallows in Canada nested in human-made habitats. Here we provide an update on the proportion of Bank Swallow nesting colonies in natural and human-made habitats in Canada’s provinces and territories based on data from a variety of sources including breeding bird atlases and eBird. Bank Swallow nesting colonies reported from 2001 to 2017 throughout Canada indicate a reversal in the dominant type of habitat used for nesting, with a 56% probability that nesting occurrences are now found in natural habitats. We discuss possible mechanisms responsible for the apparent reversal and recommend that natural nesting habitat be formally protected and restored where it has been altered, especially where co-benefits include climate change resiliency. With the support of landowners and industry, active colonies in human-made habitats will likely make an important contribution to a resilient Bank Swallow population, the majority of which presently appears to nest in natural habitats across the country

The Last Glacial Maximum and Deglacial History of the Seno Skyring Ice Lobe (52°S), Southern Patagonia

There are still many uncertainties about the climatic forcing that drove the glacier fluctuations of the Patagonian Ice Sheet (PIS, 38–55°S) during the last glacial period. A key source of uncertainty is the asynchrony of ice lobe fluctuations between the northern, central, and southern PIS. To fully understand the regional trends requires careful mapping and extensive geochronological studies. This paper presents geomorphological and geochronological reconstructions of the glacial and deglacial landforms formed during the last glacial period at the Seno Skyring lobe, southernmost Patagonia (52°S, 71°W). We present a detailed geomorphological map, where we identify two moraine systems. The outer and older is named Laguna Blanca (LB) and the inner Río Verde (RV). The LB moraines were built subaerially, whereas parts of the RV were deposited subaqueously under the palaeo lake Laguna Blanca, which developed during deglaciation. We conducted surface exposure 10Be dating methods on boulder samples collected from LB and RV glacial margins. The moraine LB III and LB IV formed at 26.3 ± 2.3 ka (n = 5) and 24.3 ± 0.9 ka (n = 3), respectively. For the inner RV moraine, we obtained an age of 18.7 ± 1.5 ka (n = 6). For the palaeo Laguna Blanca evolution, we performed 10Be exposure ages on shoreline berms and optically stimulated luminesce dating to constrain the lake levels, and 10Be depth profile dating on an outwash deposit formed by a partial lake drainage event, which occurred at 22 ± 3 ka. For the RV moraine deglaciation, we performed radiocarbon dating of basal sediments in a peat bog, which indicates that the glacier retreated from the terminal RV moraine by at least c. 16.4 cal kyr BP. Our moraine geochronology shows an asynchrony in the maximum extents and a different pattern of ice advances between neighbouring lobes in southern Patagonia. We speculate that this may be due, at least in part, to the interaction between topography and the precipitation carried by the southern westerly wind belt. However, we found broad synchrony of glacial readvances contemporaneous with the RV moraine

The evolution of the Patagonian Ice Sheet from 35 ka to the present day (PATICE)

We present PATICE, a GIS database of Patagonian glacial geomorphology and recalibrated chronological data. PATICE includes 58,823 landforms and 1,669 geochronological ages, and extends from 38°S to 55°S in southern South America. We use these data to generate new empirical reconstructions of the Patagonian Ice Sheet (PIS) and subsequent ice masses and ice-dammed palaeolakes at 35 ka, 30 ka, 25 ka, 20 ka, 15 ka, 13 ka (synchronous with the Antarctic Cold Reversal), 10 ka, 5 ka, 0.2 ka and 2011 AD. At 35 ka, the PIS covered of 492.6 x103 km2, had a sea level equivalent of ~1,496 mm, was 350 km wide and 2090 km long, and was grounded on the Pacific continental shelf edge. Outlet glacier lobes remained topographically confined and the largest generated the suites of subglacial streamlined bedforms characteristic of ice streams. The PIS reached its maximum extent by 33 – 28 ka from 38°S to 48°S, and earlier, around 47 ka from 48°S southwards. Net retreat from maximum positions began by 25 ka, with ice-marginal stabilisation then at 21 – 18 ka, which was then followed by rapid irreversible deglaciation. By 15 ka, the PIS had separated into disparate ice masses, draining into large ice-dammed lakes along the eastern margin, which strongly influenced rates of recession. Glacial readvances or stabilisations occurred at least at 14 – 13 ka, 11 ka, 6 – 5 ka, 2 – 1 ka, and 0.5 – 0.2 ka. We suggest that 20th century glacial recession (% a-1) is occurring faster than at any time documented during the Holocene

Data for: The evolution of the Patagonian Ice Sheet from 35 ka to the Present Day (PATICE)

Supplementary Data. Includes Excel data tables for ages and shapefiles for ages, geomorphology and ice-sheet reconstruction

Data for: The evolution of the Patagonian Ice Sheet from 35 ka to the Present Day (PATICE)

All data used in the PATICE database is available in the Supplementary Information, which comprise: • Full Excel tables of recalibrated published ages (including all data required to rerun the calculations). • ESRI Shapefiles of each dating technique and compiled geomorphology. • ESRI Shapefiles of outlines of ice extent and uncertainty in the ice margin. • ESRI Shapefile of ice flow and ice divide at the LLGM. • ESRI Shapefile of names of outlet lobes