Impacts of Man-Made Landscape Features on Numbers of Estuarine Waterbirds at Low Tide

Abstract

The potential impact of human disturbance on wintering waterbirds using intertidal mudflats was considered by relating their numbers to the presence of nearby footpaths, roads, railroads, and towns. Data were obtained for six English estuaries from the Wetland Bird Survey Low Tide Count scheme. Counts were undertaken monthly from November to February, and data were available for an average of 2.8 years per estuary for the period 1992-1993 to 1999-2000. Count sections and the positions of man-made landscape features were mapped using a GIS. Generalized linear models tested whether bird numbers varied according to the estuary, month, area, whether or not the section bordered water, and the proportion of each section within a specified distance of each landscape feature. In addition, the proximity of sections to the nearest footpath access point was considered. Numbers of six of nine species, northern shelduck (Tadorna tadorna), red knot (Calidris canutus), dunlin (Calidris alpina), black-tailed godwit (Limosa limosa), Eurasian curlew (Numenius arquata) and common redshank (Tringa totanus), were significantly lower where a footpath was close to a count section, while those of brant (Branta bernicla) were greater. Northern shelduck, black-bellied plover (Pluvialis squatarola), dunlin, and black-tailed godwit numbers were reduced close to railroads and those of common ringed plover (Charadrius hiaticula), black-bellied plover, and Eurasian curlew close to roads. Common ringed plover numbers were greater close to towns. The relative distances to which species were affected by footpaths corresponded to published information concerning their flight distances in response to human disturbance. The study provided evidence that sustained disturbance associated with footpaths, roads, and railroads reduced local habitat quality for waterbirds and the carrying capacity of estuaries.

The effect of rice field fragmentation on wintering waterbirds at the landscape level

“…Burton et al (2002) pointed out the presence of developed area may cause habitat loss and habitat fragmentation, or bring in human disturbances. Yet developed areas in Yilan occurred in small patches intermingled with other habitat types, and the total percentage of developed area remained low.…”

“…The impact of habitat fragmentation caused by developed areas may be low in our case. The impact of human disturbances may be low because some waterbird species are tolerant to human disturbance (Burton et al 2002). This does not mean an increase in developed area has no negative effect.…”

“…Some species use rice fields as their main habitat, while others only use rice fields as temporary alternative habitat. Some species may be tolerant of human disturbance, while others may not (Burton et al 2002). For these reasons, we hypothesize that waterbird species composition in rice fields may vary with: (1) the amount and spatial arrangement of adjacent rice fields, (2) the amount of other types of adjacent wetlands, and (3) the amount of adjacent developed area.…”

Assessing Bird Exclusion Effects in a Wetland Crossed by a Railway (Sado Estuary, Portugal)

“…12, Múrias and colleagues, in a study akin to a BACI design, reported significantly lower shorebird abundances in saltpans close to a new railway that had recently begun to operate. Another study by Burton et al (2002) reported reduced wader abundances in relation to footpaths, roads and railroads, although this greatly varied across species and human structures. Together, these studies suggest that the exclusion effects of railways on wetland birds may be small in some cases but not in others, and thus drawing generalities would require a larger number of studies covering a wide range of socio-ecological contexts.…”

Urbanization effects on watershed habitat potential: a multivariate assessment of thresholds and interactions

“…Traffic volume had a negative effect on breeding with extremely heavy traffic reducing bird presence and breeding up to 1200 m from a road (Forman and Deblinger, 2000). Burton et al (2002) found that persistent disturbance along footpaths, roads, and railroads in Gibbs (1998) was associated with large differences in the ability of amphibians to cross roads and disperse into natural forests in Southern Connecticut. In protected desert landscapes, a direct relationship between bird habitat potential and relative abundance of many species was correlated to the total length of roads and spatial distance (Gutzwiller and Barrow, 2003).…”