Spacing of point counts for grassland bird surveys in small geographical areas: Biases and tradeoffs

Lloyd W. Morrison; David G. Peitz

doi:10.1676/19-00117

Factors affecting detection probability, effective area surveyed, and species misidentification in grassland bird point counts

The Condor ◽

10.1093/condor/duz030 ◽

2019 ◽

Vol 121 (3) ◽

Author(s):

Elizabeth A Rigby ◽

Douglas H Johnson

Keyword(s):

Wind Speed ◽

Detection Probability ◽

Effective Area ◽

Probability Of Detection ◽

Bird Songs ◽

Grassland Bird ◽

Point Count ◽

Factors Affecting ◽

Logistic Regression Models ◽

Point Counts

ABSTRACT We simulated bird surveys using recorded bird songs to assess factors affecting detection probability in grassland bird point counts. We used mixed effects logistic regression models to estimate effects of those factors and to estimate and visualize the variation in the area around the observer where birds can be perceived (the perception area). We simulated surveys with 8,926 binary opportunities for detection in Minnesota grasslands in 2011 and 2012. Species, distance to the observer, wind speed and direction, observer, and density of vegetation all affected detection of recorded bird songs. Species had a strong effect; the size of the predicted perception area around the observer differed by an order of magnitude among species. Wind also had a strong effect on detection. As wind speed increased, probability of detection downwind of the observer was reduced and the perception area around the observer became smaller and more asymmetrical. The effective distance at which an observer is more likely to detect a bird than not detect it may differ among species and angles to the wind, even within the same survey. Eight of 10 species had low probability of misidentification (≤0.03), but Grasshopper Sparrow (Ammodramus savannarum) and LeConte’s Sparrow (Ammospiza leconteii) were frequently misidentified (probability = 0.09–0.24 among observers), contributing to a low rate of correct detection for those species. We recommend collecting point-count data within distance bands so that data can be analyzed based on the effective radius for each species and standardizing surveys across wind conditions to reduce variation in detection probability.

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Santa Fe Watershed Fuels Reduction Project: Avian Point Counts

Forest Service Research Data Archive ◽

10.2737/rds-2008-0003 ◽

2012 ◽

Author(s):

Karen E. Bagne ◽

Deborah M. Finch

Keyword(s):

Santa Fe ◽

Fuels Reduction ◽

Point Counts

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Grassland bird nesting ecology: video samples of behavior

Forest Service Research Data Archive ◽

10.2737/rds-2018-0034 ◽

2018 ◽

Author(s):

Christine A. Ribic ◽

Nicola Koper ◽

Christoph S. Ng ◽

Kevin S. Ellison

Keyword(s):

Nesting Ecology ◽

Grassland Bird

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Die Brutvogelfauna eines Nadelwaldes der nördlichen Voralpen nach dem Sturm Lothar

Schweizerische Zeitschrift fur Forstwesen ◽

10.3188/szf.2017.0059 ◽

2017 ◽

Vol 168 (2) ◽

pp. 59-66

Author(s):

Pierre Mollet ◽

René Hardegger ◽

Res Altwegg ◽

Pius Korner ◽

Simon Birrer

Keyword(s):

Forest Succession ◽

Coniferous Forest ◽

Bird Species ◽

Individual Species ◽

Mountain Forest ◽

Breeding Bird ◽

Point Counts ◽

Federal Institute ◽

Central Switzerland ◽

Bird Fauna

Breeding bird fauna in a coniferous forest in the northern Prealps after storm Lothar In a 70-hectare large coniferous forest located on the northern edge of the Alps in central Switzerland, Canton of Obwalden, at an altitude of 1260 to 1550 metres above sea level, we surveyed the local breeding bird fauna in 2002 and 2013 by means of point counts as well as additional area searches for rare species. In December 1999, hurricane Lothar caused two large windthrow areas and several smaller areas with scattered throws in the survey range. We found a total of 48 breeding bird species, which is a very diverse species composition for a mountain forest. In the eleven years between surveys, a decline in distribution or abundance was recorded for four species, while seven species showed an increase; a further four species showed no change. For the remaining species, the data sets were too small to reliably estimate changes. A comparison with forest structure data provided by the Swiss Federal Institute of Forest, Snow and Landscape Research WSL revealed that for five bird species, the changes in distribution or abundance could be explained at least partially by forest succession. In order to obtain realistic distribution and abundance values in this kind of breeding bird survey, it is essential to collect large enough samples and to consider the detection probability of each individual species using appropriate statistical methods.

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Stand-Level Forest Structure and Avian Habitat: Scale Dependencies in Predicting Occurrence in a Heterogeneous Forest

Forest Science ◽

10.1093/forestscience/54.1.36 ◽

2008 ◽

Vol 54 (1) ◽

pp. 36-46

Author(s):

Katherine Manaras Smith ◽

William S. Keeton ◽

Therese M. Donovan ◽

Brian Mitchell

Keyword(s):

Forest Structure ◽

Stand Structure ◽

Site Occupancy ◽

Territory Size ◽

Weight Of Evidence ◽

Habitat Models ◽

Point Counts ◽

Forest Stand Structure ◽

Habitat Scale

Abstract We explored the role of stand-level forest structure and spatial extent of forest sampling in models of avian occurrence in northern hardwood-conifer forests for two species: black-throated blue warbler (Dendroica caerulescens) and ovenbird (Seiurus aurocapillus). We estimated site occupancy from point counts at 20 sites and characterized the forest structure at these sites at three spatial extents (0.2, 3.0, and 12.0 ha). Weight of evidence was greatest for habitat models using forest stand structure at the 12.0-ha extent and diminished only slightly at the 3.0-ha extent, a scale that was slightly larger than the average territory size of both species. Habitat models characterized at the 0.2-ha extent had low support, yet are the closest in design to those used in many of the habitat studies we reviewed. These results suggest that the role of stand-level vegetation may have been underestimated in the past, which will be of interest to land managers who use habitat models to assess the suitability of habitat for species of concern.

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Is Hay for the Birds? Investigating Landowner Willingness to Time Hay Harvests for Grassland Bird Conservation

Animals ◽

10.3390/ani11041030 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1030

Author(s):

Matthew Gruntorad ◽

Katherine Graham ◽

Nico Arcilla ◽

Christopher Chizinski

Keyword(s):

Great Plains ◽

Critical Factor ◽

Information Support ◽

Conservation Strategies ◽

Bird Conservation ◽

Willingness To Participate ◽

Population Declines ◽

Grassland Bird ◽

The North ◽

Hunting Activity

Birds in agricultural environments have exhibited steep global population declines in recent decades, and effective conservation strategies targeting their populations are urgently needed. In grasslands used for hay production, breeding birds’ nest success improves substantially if hay harvests are delayed until after mid-July. However, few studies have investigated private hay producers’ willingness to alter their harvesting practices, which is a critical factor for bird conservation where most land is privately owned, such as in the North American Great Plains. We surveyed Nebraska hay producers to examine whether livestock production, wildlife knowledge, and hunting activity affects their willingness to alter haying practices for bird conservation. The majority (60%) of respondents expressed willingness to delay harvesting hay to allow birds time to nest successfully. Livestock producers and those more knowledgeable about wildlife were more willing to delay hay harvests, whereas active hunters were less willing to do so. Our findings suggest that a majority of private producers show a high potential for engaging in grassland bird conservation activities. Landowners’ willingness to participate in bird conservation programs and actions could be further encouraged through extension and education efforts connecting hay producers with information, support, and funding for bird conservation.

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On the use of 10-minute point counts and 10-species lists for surveying birds in lowland Atlantic Forests in southeastern Brazil

Papéis Avulsos de Zoologia ◽

10.1590/s0031-10492012002800001 ◽

2012 ◽

Vol 52 (28) ◽

pp. 333-340 ◽

Cited By ~ 2

Author(s):

Vagner Cavarzere ◽

Thiago Vernaschi Vieira da Costa ◽

Luís Fábio Silveira

Keyword(s):

Rapid Assessment ◽

Southeastern Brazil ◽

Point Counting ◽

Point Count ◽

Point Counts ◽

Time Period ◽

Minute Point ◽

Species Lists ◽

Point Count Method ◽

Breeding Seasons

Due to rapid and continuous deforestation, recent bird surveys in the Atlantic Forest are following rapid assessment programs to accumulate significant amounts of data during short periods of time. During this study, two surveying methods were used to evaluate which technique rapidly accumulated most species (> 90% of the estimated empirical value) at lowland Atlantic Forests in the state of São Paulo, southeastern Brazil. Birds were counted during the 2008-2010 breeding seasons using 10-minute point counts and 10-species lists. Overall, point counting detected as many species as lists (79 vs. 83, respectively), and 88 points (14.7 h) detected 90% of the estimated species richness. Forty-one lists were insufficient to detect 90% of all species. However, lists accumulated species faster in a shorter time period, probably due to the nature of the point count method in which species detected while moving between points are not considered. Rapid assessment programs in these forests will rapidly detect more species using 10-species lists. Both methods shared 63% of all forest species, but this may be due to spatial and temporal mismatch between samplings of each method.

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