The effects of visual apparency on bias in butterfly recording and monitoring

Dennis, Roger L. H.; Shreeve, Tim G.; Isaac, Nick J. B.; Roy, David B.; Hardy, Peter B.; Fox, Richard; Asher, Jim

doi:10.1016/j.biocon.2005.10.015

Cited by 87 publications

(71 citation statements)

References 24 publications

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“…Plant richness and habitat diversity data originated from Sprynar Records of vagrant species with erratic occurrence and those of hardly detectable species with arboreal habit may bias comparisons of past and present faunas (Dennis et al, 2006). This was of particular concern, because numbers of visits to individual reserves varied in the past survey, and also because the past survey spanned many years, which increased the chances of recording occasional vagrants.…”

Section: Species Traits and Reserve Characteristicsmentioning

confidence: 99%

Revisiting urban refuges: Changes of butterfly and burnet fauna in Prague reserves over three decades

Kadlec

Beneš

Jaros̆ı́k

et al. 2008

Landscape and Urban Planning

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We studied changes in the composition of butterfly and burnet fauna in 25 reserves of xeric grasslands within the city Prague, Czech Republic, based on a recent repetition of a survey conducted three decades ago. The past and recent survey detected 91 and 84 species, 12 species were lost and four were gained between the surveys. There was no significant change in mean numbers of species per reserve or in mean species incidences, even if the categories of the habitat association, mobility and body size were analysed separately. Contrary to these comparisons, ordination analyses indicated a significant shift in species composition in individual reserves. Species of short-sward xeric grasslands tended to be associated with the past survey, whereas species of taller grasslands and xeric scrub were associated with recent survey. These shifts were more prominent in large reserves with high proportion of natural (as opposed to urban) perimeter, connected with other reserves, having diverse topography and high plant and biotope richness. We interpret this by gradual successional changes which affect the reserves despite conservation management. Despite these changes, butterfly losses were lower than in comparable surveys recently conducted elsewhere in Central Europe, partly because major losses occurred long before the 1980s survey and partly owing to a high heterogeneity of the urban landscape surrounding the reserves.

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Section: Species Traits and Reserve Characteristicsmentioning

confidence: 99%

Revisiting urban refuges: Changes of butterfly and burnet fauna in Prague reserves over three decades

Kadlec

Beneš

Jaros̆ı́k

et al. 2008

Landscape and Urban Planning

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“…Otherwise, patterns explaining species-specific variability in calibration ratios were difficult to identify. Dennis et al (2006) obtained relatively more significant patterns related to higher (or sooner) butterfly numbers detected than in this study, in much larger datasets that involved more varied vegetation (i.e., canopy heights) but with some variation in which variables mattered and how among those datasets. Significant variables relevant to this study included wing length (although contradictorily), brightness, and long flight periods.…”

Section: Calibrationmentioning

confidence: 75%

“…Likewise, Dennis et al (2006) analyzed the relationship of higher (or sooner) recorded butterfly numbers to variables similar to the ones here: wing length, brightness of coloration (cf. detectability code here), and length of flight period (cf.…”

Section: Calibrationmentioning

confidence: 99%

Meta-analysis of survey data to assess trends of prairie butterflies in Minnesota, USA during 1979–2005

Schlicht

Swengel²,

Swengel³

2008

J Insect Conserv

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During 1993-1996, two teams (Schlicht, Swengels) surveyed the same Minnesota prairies, but without any coordination of sites, routes, methods, dates, and results between teams. In 27 instances, both teams surveyed the same site in the same year between 30 June and 18 July. For the 18 most frequently recorded species, abundance indices (individuals/h per site) significantly covaried between teams for 11 (61%) species, including 2/3 prairie specialists tested. No species significantly correlated negatively, 17/18 species had positive correlations, and the preponderance of positive correlations was significant. Swengel indices per hour (two surveyors; unlimited-width transect) averaged 2.42 times Schlicht indices (one surveyor; fixed-width transect). These results demonstrate that transect surveys by different teams at the same sites but not the same routes produce similar rankings of species abundance among sites. This approach to population monitoring (transect surveys during the season that covers the most specialist species at once, not necessarily with fixed routes but recording all species seen) might also be appropriate in other regions with high habitat loss and low human population density. Abundance indices from surveys by seven teams spanning 1979-2005 were calculated for evaluating population trends. For the five analyzable specialist species, 25/30 population trend tests of a species at a site had a negative direction, a highly significant skewing (P \ 0.0001). By contrast, five ''common'' (most frequently recorded non-specialist) species had an even distribution of negative and positive trends. While adjacent sites had similarly timed decline thresholds (last year when a higher rate or any individual was recorded vs. first year when all subsequent indices were lower or zero) within species, these thresholds were not synchronized among sites in different counties. All sites analyzed in this study were preserves managed primarily with fire. While the ecosystem (or vegetative) approach to reserve selection has been validated in other studies to be effective at capturing populations of associated specialist butterflies, butterfly declines after reserve designation will likely continue unless the ecosystem approach to reserve management includes specific consideration of individual butterfly species' required resources and management tolerances.

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“…Butterflies are the most widely studied of all insect groups (Dennis et al 2006, van Swaay et al 2008, and their sensitivity to environmental change together with the availability of butterfly data makes this group very useful as indicators for biodiversity (New 1997, Thomas 2005, Dennis et al 2006, van Swaay et al 2015. Furthermore, since many butterfly species require a warm microclimate for optimal growth and development (Wallisdevries andVan Swaay 2006, Eilers et al 2013), they can also serve as indicators for climatic change (Thomas 2005, van Swaay et al 2008, Betzholtz et al 2013.…”

Section: Introductionmentioning

confidence: 99%

Butterfly monitoring using systematically placed transects in contrasting climatic regions – exploring an established spatial design for sampling

Videvall¹,

Öckinger²,

Pettersson³

2016

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Citation: Videvall E, Öckinger E, Pettersson LB (2016) Butterfly monitoring using systematically placed transects in contrasting climatic regions -exploring an established spatial design for sampling. Nature Conservation 14: 41-62. doi:10.3897/natureconservation.14.7497 AbstractButterfly monitoring schemes are recording programs initiated to monitor nationwide butterfly abundance and distribution patterns, often with help from volunteers. The method generates high-resolution data, but may be associated with a degree of habitat sampling bias if volunteers prefer to survey areas perceived to be high-quality butterfly habitats. This can result in habitats becoming underrepresented in the data set, leading to less information about the butterfly populations there. In the present study, we investigate the possibility of applying a spatial design used by the Swedish Bird Survey for nationwide, gridbased sampling, with a goal to get butterfly monitoring data covering a representative sample of different habitats. We surveyed four 2×2 km sampling squares, split into 100 m segments, in the southernmost region of Sweden (Scania) and four in the northernmost region (Norrbotten). The grid-based transects were compared with volunteer-selected transects in a GIS analysis using a refined Swedish version of CO-RINE land cover data to see how well these two transect designs represent true habitat coverage. A total of 53 km transect was monitored, resulting in 490 individuals and 29 different species recorded. We found that transect cover correlated significantly with overall land cover using both monitoring methods, though standardised transects outperformed volunteer-selected transects in habitat representation in Scania, but not in Norrbotten. Butterflies were found to aggregate significantly in specific habitats, but with contrasting results for the two geographically different regions. Grasslands in both regions generated a high number of recorded butterflies, although so did clear-cut and residential areas in Norrbotten as well. The

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The effects of visual apparency on bias in butterfly recording and monitoring

Cited by 87 publications

References 24 publications

Revisiting urban refuges: Changes of butterfly and burnet fauna in Prague reserves over three decades

Revisiting urban refuges: Changes of butterfly and burnet fauna in Prague reserves over three decades

Meta-analysis of survey data to assess trends of prairie butterflies in Minnesota, USA during 1979–2005

Butterfly monitoring using systematically placed transects in contrasting climatic regions – exploring an established spatial design for sampling

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