Reports on distances between colonies and feeding sites vary. Radio-tagged breeding birds along the north shore of the Lake Erie bluffs spent most of their time foraging within m of the colony Appendix B :. There is no information regarding diet or foraging behaviour during migration or on the wintering grounds. Bank Swallows are long-distance, diurnal migrants, travelling from North America to their wintering areas in northern and central South America Garrison Compared to European populations, very little is known about Bank Swallow migration and dispersal in Ontario, let alone North America.

Another band encounter record shows an adult bird that travelled almost km from southern Ontario to southern Missouri in 22 days during the month of July Brewer et al. Based on the frequency of observation records, the main migratory route is likely through the Central America isthmus, although small numbers of birds occur regularly on some Caribbean islands Garrison Bank Swallows generally arrive in Ontario starting in mid- to late April and continue through May, and most depart starting in late July and continue through August and September.

The frequency of eBird checklists reported in Ontario shows the spring migration peak in the second week of May and the fall migration peaking from the first to third week of August eBird Surviving adults generally return to breeding sites i. Predation, bank collapse, or other events that result in nest mortality have an apparent influence on philopatry in successive years i.

New birds will apparently recolonize these sites in successive years Freer Successful breeding at a site has been found to increase the probability that the bank will be recolonized in successive years Freer In contrast, adult return rates summarized in Freer range from 4 to 13 percent, but these data are based on initial bandings of tens of thousands of birds over 6 to 17 years. Banding studies with larger sample sizes over more years and sites are needed to determine whether the low return rates are due to high inter-annual dispersal, low survival rates, or both.

In the United Kingdom, fledged juveniles disperse widely up to several hundred kilometres and use different nocturnal roost sites on a nightly basis, whereas adults tend to repeatedly use a single roost site close to the breeding colony Mead and Harrison Juveniles visit multiple colonies during this dispersion, presumably assessing the suitability of breeding sites for future years. Juveniles also initiate fall migration later than adults Mead and Harrison Migratory movements are funnelled through lowland river valleys where foraging opportunities are presumed to be favourable Mead and Harrison In North America, the Bank Swallow breeds across most of Canada and Alaska south of the treeline and across the northern two-thirds of the United States.

In Ontario, the Bank Swallow breeds across the entire province; however, it is most common in southern Ontario south of the Canadian Shield, where glacial outwash deposits e. The Bank Swallow is more sparsely distributed throughout the Canadian Shield and Hudson Bay Lowland regions, where it occurs locally in aggregate pits and along large river corridors Figure 2 , Sandilands Figure 2.

Breeding distribution of the Bank Swallow in Ontario. Based on Breeding Bird Atlas data see Cadman et al. Coloured squares indicate that Bank Swallow was reported in a 10 km square during both atlas periods and Black dots identify squares where Bank Swallow was recorded during , but not during Yellow dots identify squares where the species was recorded during the second atlas, but not the first.

Inset map shows distribution on km block scale. It is not known to what extent the distribution and abundance of the Bank Swallow has changed since prior to European settlement. Historically, Bank Swallows nested only in natural habitats created by erosion, including riverbanks and lake bluffs. Changes that have likely increased Bank Swallow distribution include the increase in open foraging habitat resulting from clearing of forests, and availability of nesting opportunities at human-made sites, such as aggregate pits and road cuts COSEWIC Changes that have likely reduced Bank Swallow distribution include the loss of nest sites along many waterways in Ontario due to water control structures, channeling of rivers, and erosion control measures COSEWIC The temporal and geographic scope of these monitoring surveys varies, as does the accuracy of resulting estimates of relative density and abundance.

Estimates based on BBS data from to suggest that the Ontario Bank Swallow population was approximately , individuals representing about 1 percent of the global 19 million , 3 percent of the continental 6 million , and 17 percent of the national 1. Given that the Ontario Bank Swallow population has been declining 4.

The reliability of the BBS population estimate may be questionable though, as the BBS does not likely sample colonial species precisely enough to confidently estimate population size. The BBS likely over-samples birds nesting in human-made habitat and under-samples colonies in natural habitat, particularly the large populations found along the lower Great Lakes shorelines. For example, no more than Bank Swallows were recorded during BBS surveys between and on the two survey routes located closest to the large Lake Erie shoreline population described below , even though portions of these routes are within 3.

Abundance data from the Ontario Breeding Bird Atlas include extensive point counts on- and off-road , and population information was reported for many individual colonies. The Atlas data indicate high densities of birds along the north shores of Lakes Ontario and Erie, as well as large colonies on the Saugeen River Figure 3 , Sandilands Many Bank Swallow colonies were unreported or under-reported during the Atlas Sandilands A population estimate based on Atlas data is not available due to the limitation of using the point count sampling method for deriving population size estimates for a colonial nesting species.

Figure 3. Relative abundance of the Bank Swallow within northern and southern Ontario. Based on Breeding Bird Atlas point count data collected in Cadman et al. The most accurate abundance information for this species in Ontario is a series of Bank Swallow burrow count inventories conducted on Lakes Ontario and Erie, Saugeen River and other rivers, and aggregate pits throughout Ontario between and The population estimate for breeding birds on Lake Erie derived from these burrow counts is about , individuals Appendix B : , while Lake Ontario supports about 20, individuals Leung unpub.

The population estimate for Bank Swallows breeding in aggregate pits and quarries in Ontario is about , individuals Browning and Cadman unpub. Browning, pers. All population estimates from burrow count surveys assume a burrow occupancy rate of 50 percent and two adults per occupied burrow Wright et al.

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Much of northern Ontario has not been thoroughly surveyed. Atlas data indicate there are many probably small colonies scattered across northern Ontario, but overall this population likely represents a substantially smaller number of birds compared to southern Ontario Sandilands One exception is colonies along the rivers in the Hudson Bay Lowlands, which may be of provincial significance. An assessment of the population size in the Hudson Bay Lowlands is needed to accurately estimate the population size for the province.

The best available information see above burrow count surveys indicates that the Ontario Bank Swallow breeding population is in the order of , individuals. This estimate may be conservative, as it excludes estimates from rivers in the Hudson Bay Lowlands and other areas, and miscellaneous habitats e. Some proportion of individuals in a given population in a given year consists of non-breeding individuals referred to as "floaters" Kokko and Sutherland No information exists on floater population dynamics of Bank Swallows.

However, the proportion of floaters likely varies temporally and geographically depending on population size affected by reproductive success in previous year and over-winter survival , and habitat quality and quantity. These relationships are complex, as high quality habitat can produce large numbers of recruits into the floater population, and a large total population decline can occur without a substantial decrease in the number of breeders Kokko and Sutherland More study is needed to understand floater population dynamics in the Bank Swallow.

Despite large sample sizes, BBS trends are considered only moderately reliable as the survey design for underlying point count data is not well-suited to accurately sample colonial species Environment Canada a. In the short-term , the Bank Swallow population has continued to decline significantly, but at a lesser rate in Ontario Since the s, Bank Swallow short-term trends based on BBS data from Ontario show that the severity of the decline has been gradually lessening A.

Smith, pers. Bank Swallow trends throughout the rest of North America show significant declines in most regions and jurisdictions Nebel et al. No regions or jurisdictions show significant increases in Bank Swallow populations Sauer et al. Recent analysis of aerial insectivore populations using BBS data shows evidence for the initiation of declines during the s for the entire group of swifts, swallows and nightjars across most of North America, although trends and trajectories on either side of the change point vary spatially and temporally both within and across species Smith et al.

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In Europe, several studies report population declines associated primarily with changes in the aggregate industry e. See section 1. Figure 4. Long-term population indices for Bank Swallows in Ontario during Table 2. Long and short-term estimates of population change for the Bank Swallow in Ontario and Canada.

Boldface denotes significant trends.

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Measures of overall reliability of trends are defined by span of geographic coverage, model fit and precision of estimates see Environment Canada b. Figure 5. Enlarge Figure 5. Bird Conservation Regions in Ontario map. Figure 6.

Ecoregion boundaries used in the Ontario Breeding Bird Atlas analysis. Enlarge Figure 6. Ecoregion boundaries map. The probability of observation standardized for 20 hours of observation effort for the Bank Swallow decreased by 45 percent in Ontario between atlas periods and ; Cadman et al. Similarly, annual burrow counts from to on the Saugeen River in Ontario fluctuate considerably and suggest no apparent trend Cadman and Southcott-Lebrun These findings are, perhaps, not surprising given the few years of study.

Figure 7. Annual Bank Swallow burrow counts along 64 km of monitored sections from the north shore of Lake Erie. Bank Swallow habitat needs include foraging habitat, nest sites and nocturnal roost sites. Access to suitable foraging areas with a reliable supply of insect prey is necessary throughout their life cycle. Breeding birds require a suitable nest site in proximity to foraging habitat.

In addition, Bank Swallows require suitable habitat for roosting at night at all times of the year.

As with other swallow species, migratory stopover points are usually centred on large marshes where birds roost at night and disperse to forage throughout the day Turner , Winkler There is little information available for Bank Swallows in terms of the importance of area requirements of these disparate habitats and their proximity to each other. Bank Swallows forage in a variety of open terrestrial and aquatic habitats including wetlands, open water, riparian woodlands, grasslands, and agricultural areas, as well as shrubland Garrison Regions with dense forest cover are generally avoided at all times of the year.

During the pre-migratory period i. Grassland habitat may be a preferred foraging habitat type when located in relatively close proximity to a breeding site.

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In California, increased distances between colonies and nearest grassland habitat was positively related to colony extinction probabilities Moffatt et al. Limited information is known about the foraging habitat used by Bank Swallows in Ontario, other than breeding birds mostly forage in open habitats up to metres from the colony Turner , Appendix B :. See Diet and foraging behaviour for information on diet and foraging behaviour, including foraging distances.

During migration and on the wintering grounds Bank Swallows forage over a variety of open and aquatic-based habitats, including wetlands, mangrove lagoons, ocean coasts, mudflats, and agricultural areas Garrison In Paraguay, wintering Bank Swallows forage over open water habitats more than over fields, marshes, or beaches Hayes et al. More information on foraging habitat preferences is needed throughout the life cycle of the Bank Swallow. During the breeding season i. Natural erosion and human-related excavation of material refreshes the vertical profile and keeps the bank suitable for nesting.

If the vertical face of a bank is not maintained or "refreshed", it usually slumps and stabilizes within several years, at which point the colony disappears Garrison , Ghent a, J. Bayliss, pers. Typical examples of suitable nesting sites include eroding lake bluffs and river banks, extraction faces in aggregate pits, and topsoil piles in construction areas.

Some less common sites include woodchip and ash piles, and pre-existing drain holes in concrete structures e. Nest record reports may be biased towards human-made habitats that are easier to access i. It is unknown if these proportions have changed since the late s, so more study may be necessary.

Attempts to create human-made nesting structures for Bank Swallows have met with varied success Hopkins , M. Leung, pers. McDonald, pers. Structures range from cement bunker styles with pre-existing, sand-filled burrows to more natural embankments consisting of layers of clay-sand mixtures.

In Ontario, very limited or no success has been achieved with these nesting structures.

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In most cases, birds have not nested in the structures, despite some birds excavating early in the season. In one case, a colony with 32 burrows was established in a human-made bank composed of natural materials, although it was later depredated by a predator K. In contrast, similar structures created in Europe have been successful Hopkins The reason s for the discrepancy in occupancy rates of nest structures between Europe and Ontario is currently unknown.

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More study is needed. The substrate characteristics of nest sites has received considerable attention Petersen , Spencer , Hickman , Hjertaas , Jones , John , Heneberg , Lind et al. In general, substrate penetrability and the varying proportions of substrate particle sizes are important for burrowing.

Colony sizes also tend to be greater where the proportion of silt to sand is greatest Hjertaas , John , Garrison Bank length is positively related to bank occupancy, while woody vegetation on the talus slope below the bank is negatively related to bank occupancy Hjertaas , Tozer and Richmond Open space of at least 60 m out from the bank is needed as Bank Swallows require open flying space for vertical lift when exiting nest burrows Hjertaas Bank erosion processes and rates are likely related to bank structure and vegetation characteristics Garcia , but few studies have examined the effect of erosion on Bank Swallow habitat selection.

Waterbodies and watercourses are often associated, although likely indirectly, with Bank Swallow colonies, since they are often the source of erosion for suitable nesting banks. Notable exceptions include aggregate pits, where banks are created and maintained using heavy machinery. Ghent a showed that removal of talus to increase bank height to about 2 m resulted in Bank Swallows reoccupying aggregate pit banks.