Contrasting Diversity Values: Statistical Inferences Based on Overlapping Confidence Intervals

MacGregor-Fors, Ian; Payton, Mark E.

doi:10.1371/journal.pone.0056794

Cited by 219 publications

(147 citation statements)

References 8 publications

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“…We then compared 84% CIs among groups, and where these did not overlap, species richness and bird density estimates were considered as significantly different with an alpha of 0.05 (Payton et al 2003, MacGregor-Fors andPayton 2013). This comparison robustly mimics the 0.05 probability obtained from statistical tests for symmetric and asymmetric CIs.…”

Section: Discussionmentioning

confidence: 99%

“…To determine whether bird species richness and community density values were statistically different among cloud forest size categories, we calculated 84% confidence intervals (CIs) for results obtained by EstimateS 9 and Distance 6.0, following detailed procedures provided in MacGregor-Fors and Payton (2013). We then compared 84% CIs among groups, and where these did not overlap, species richness and bird density estimates were considered as significantly different with an alpha of 0.05 (Payton et al 2003, MacGregor-Fors andPayton 2013).…”

Section: Discussionmentioning

confidence: 99%

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Shifts in resident bird communities associated with cloud forest patch size in Central Veracruz, Mexico

Rueda‐Hernández¹,

MacGregor-Fors²,

Renton³

2015

ACE

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ABSTRACT. Avian communities in cloud forests have high levels of endemism and are at major risk given the accelerated rate of habitat fragmentation. Nevertheless, the response of these communities to changes in fragment size remains poorly understood. We evaluated species richness, bird community density, community composition, and dominance as indicators of the response to fragment size in a fragmented cloud forest landscape in central Veracruz, Mexico. Medium-sized fragments had statistically higher than expected species richness and more even communities, which may be a reflection of the intermediate disturbance hypothesis, in which mediumsized fragments are exploited by both forest and disturbance-associated species. Bird density also reached higher values in mediumsized fragments, which may indicate a carrying capacity in this habitat. However, large cloud forest fragments had a distinct taxonomic and functional composition, attributable to an increased number of understory insectivore species and canopy frugivores. By comparison, omnivorous species associated with human-altered habitats were more abundant in smaller fragments. Hence, although medium-sized cloud forest fragments had higher species richness and high bird density, large forest tracts maintained a distinct avian community composition, particularly of insectivorous and frugivorous species. Furthermore, the underlying response to fragmentation can only be properly addressed when contrasting several community attributes, such as richness, density, composition, and species dominance. Therefore, cloud forest conservation should aim to preserve the remaining large forest fragments to maintain comprehensive avian communities and avoid local extinctions.Changements dans les communautés d'oiseaux résidents associés à la dimension des îlots de forêts de nuages dans le centre du Veracruz, Mexique RÉSUMÉ. Les communautés aviaires des forêts de nuages (c.-à-d., les forêts humides de montagne) ont un degré d'endémisme élevé et sont très menacées considérant le rythme accéléré de la fragmentation de l'habitat. Néanmoins, la réponse de ces communautés en réaction aux changements de la dimension des îlots demeure largement inexpliquée. Nous avons évalué la richesse spécifique, la densité des communautés aviaires, la composition des communautés et la dominance spécifique comme facteurs pouvant expliquer la réponse à la dimension des îlots dans un paysage fragmenté de forêts de nuages dans le centre du Veracruz, Mexique. Les îlots de taille moyenne ont montré une richesse spécifique attendue plus élevée statistiquement que les autres îlots et des communautés plus uniformes, résultat qui pourrait s'expliquer par l'hypothèse de perturbation intermédiaire selon laquelle les îlots de taille moyenne sont exploités autant par des espèces forestières que des espèces associées aux perturbations. Les valeurs de densité aviaire ont aussi été plus élevées dans ces îlots, ce qui pourrait indiquer que ce milieu a atteint sa capacité de support. Toutefois, les grands îlots de...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Shifts in resident bird communities associated with cloud forest patch size in Central Veracruz, Mexico

Rueda‐Hernández¹,

MacGregor-Fors²,

Renton³

2015

ACE

Self Cite

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“…To determine statistical differences between the density estimations between the three cities, we compared their 84% confidence intervals, following MacGregor-Fors and Payton (2013). Given that overlapping 95% confidence intervals fail in detecting statistical differences with an α ≤ 0.05, we used 84% confidence intervals, which have been shown to approximate overlapping confidence intervals with an α ≈ 0.05 for both symmetrical and asymmetrical intervals; for House Sparrow density estimations, confidence intervals are asymmetrical, from normal and log-normal distributions (Payton et al 2003, MacGregor-Fors andPayton 2013). Hence, when the 84% confidence intervals for the density estimations of two groups did not overlap, we considered them to be statistically different from one another; when their confidence intervals did overlap, we considered them to not be statistically different from one another.…”

Section: Discussionmentioning

confidence: 99%

Space invaders: House Sparrow densities along three urban-agricultural landscapes

MacGregor-Fors

Quesada²,

Lee

et al. 2017

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ABSTRACT. One of the most successful avian urban invaders is the House Sparrow (Passer domesticus). Here, we examine House Sparrow numbers in the urban-agricultural landscape of three cities, one where the sparrow is native (Barcelona) and two where it is nonnative (Los Angeles, Mexico City), comparing between five different land classes based on land-use, location relative to urban center, and urbanization intensity. We estimated sparrow densities using distance-sampling corrected procedures and compared sparrow numbers between the three cities and between the land classes within each city. This two-year survey showed the highest density of sparrows occurring in Mexico City and the lowest in Los Angeles. In both cities where the sparrow is nonnative, we recorded the greatest abundances in highly urbanized areas. In Barcelona, where the sparrow is native, abundances did not differ among land classes. We also related sparrow numbers to specific environmental variables, describing vegetation structure, urban infrastructure, and human activity, using classification and regression trees. We found several variables related to differences in House Sparrow abundances among the three cities. For Los Angeles and Mexico City, the most important variables explaining House Sparrow numbers were urban infrastructure (i.e., maximum building height, high urbanization) and/or human activity (i.e., pedestrians), all of which related positively with sparrow abundance. For Barcelona, sparrow numbers showed both positive and negative relationships with vegetation (i.e., tree abundance, maximum tree height, maximum herbaceous plant height) and human-related variables (i.e., cars, pedestrians). Although the scope of this study is geographically limited to three cities, our results suggest that House Sparrow numbers between cities and land classes areas vary considerably, and are likely determined by a complex array of variables. Our study provides some insight to the growth and decline of House Sparrow populations in their nonnative and native ranges, respectively. Alerte aux envahisseurs: Densités de moineaux domestiques au long de trois paysages agrico-urbainsRÉSUMÉ. Un des envahisseurs aviaires ayant le plus de succès est le Moineau Domestique (Passer domesticus). Ici, nous examinons les densités dans les zones agrico-urbaines de trois villes, une où le moineau est natif (Barcelone) et deux où l'espèce est considérée envahissante (Los Angeles, Mexico), en comparant entre cinq classifications terrestres établit selon l'utilisation du territoire, localisation relative au centre urbain, et l'intensité d'urbanisation. Nous avons estimé les densités de moineaux en utilisant la méthode d'échantillonnage selon la distance corrigée et avons comparé le nombre de moineau entre les trois villes, ainsi qu'entre les classifications terrestres dans chaque ville. Cet échantillonnage de deux ans a démontré la plus grande densité à Mexico et la plus basse à Los Angeles. Chez les deux villes où le moineau est considéré comme envahissant, les densité...

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“…3). This metric mimics P < 0.05 statistical testing more realistically than stricter confidence intervals (MacGregor-Fors and Payton 2013).…”

Section: Discussionmentioning

confidence: 97%

Fly family diversity shows evidence of livestock grazing pressure in Mongolia (Insecta: Diptera)

et al. 2018

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Members of the insect order Diptera respond differentially to environmental changes and may play an important role in understanding the effects that livestock grazing disturbances have on biodiversity. Here we examine how increasing grazing pressures on the Mongolian steppe affect Diptera diversity and abundance. Using 2334 yellow pan traps, we sampled a total of 132 sites over four years to collect 17,348 flies. We compared fly diversity and abundance at five levels of livestock grazing. We observed that fly family diversity decreased in heavily grazed sites and that diptera communities at sites with intense grazing have proportionally higher prevalence of taxa from the families Muscidae, Sepsidae, Ephydridae, Chloropidae, and Tachinidae, two of which are often associated with animal waste. Chironomidae, Ceratopogonidae, Sarcophagidae, and Sciaridae are most prevalent at sites with very little or no grazing, and Anthomyiidae, Calliphoridae, Carnidae, Cecidomyiidae, Dolichopodidae, Empididae, Scatopsidae and Sphaeroceridae are most often encountered at sites with intermediate amounts of grazing. Observing changes in a few guilds of fly families at different grazing levels is beneficial in understanding human effects on fly diversity.

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Contrasting Diversity Values: Statistical Inferences Based on Overlapping Confidence Intervals

Cited by 219 publications

References 8 publications

Shifts in resident bird communities associated with cloud forest patch size in Central Veracruz, Mexico

Shifts in resident bird communities associated with cloud forest patch size in Central Veracruz, Mexico

Space invaders: House Sparrow densities along three urban-agricultural landscapes

Fly family diversity shows evidence of livestock grazing pressure in Mongolia (Insecta: Diptera)

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