Wildlife Population Estimates by Census and Distance Measuring Techniques

2021 ◽  
pp. 281-292
Author(s):  
Peter A. Henderson
Keyword(s):  
Fourier Series ◽  
Sampling Methods ◽  
Survey Methods ◽  
Distance Sampling ◽  
Population Estimates ◽  
Nearest Neighbour ◽  
Wildlife Population ◽  
Measuring Techniques ◽  
Line Survey ◽  
Distance Measuring

Methodologies based on counting the number of sightings to estimate are described. These techniques are particularly useful for large or easily seen animals such as birds, large grassland mammals, whales, crocodilians, and large, active insects such as butterflies. Point and line survey methods are described. Distance sampling methods, including Fourier series estimators, are presented, and R code listings to undertake the computations presented. Plotless density estimators are described based on nearest-neighbour, and closest-individual measurements are described.

scholarly journals Vulture populations in Uganda: using road survey data to measure both densities and encounter rates within protected and unprotected areas

2014 ◽  
Vol 25 (4) ◽  
pp. 399-414 ◽  
Author(s):  
DEREK POMEROY ◽  
PHIL SHAW ◽  
MICHAEL OPIGE ◽  
GEORGE KAPHU ◽  
DARCY L. OGADA ◽  
...  
Keyword(s):  
Survey Data ◽  
Survey Methods ◽  
Distance Sampling ◽  
Population Estimates ◽  
Breeding Density ◽  
Density Estimates ◽  
Encounter Rates ◽  
Two Measures ◽  
Road Survey ◽  
Agricultural Areas

SummarySix out of seven vulture species whose global ranges lie largely or wholly within Africa are listed as globally threatened. Since their current distributions individually span up to 39 range states there is a pressing need to develop robust, standardised methods that provide a clear measure of range-wide changes in abundance. Yet, survey methods currently used tend to yield either of two measures: estimates of breeding density, derived mainly from nest counts; or linear encounter rates, derived from road surveys. Here, we present the results of a six-year survey of six vulture species in Uganda, in which we used road counts, in combination with Distance sampling, to determine both encounter rates and densities within protected areas (PAs), and in predominantly pastoral and agricultural areas. In combination, five scavenging species were detected 4–6 times more frequently in PAs than elsewhere, and two species, White-backed Vulture Gyps africanus and Lappet-faced Vulture Torgus tracheliotus, were recorded only within PAs. We estimate that PAs held c.1,300–3,900 individuals of the five scavenging species combined, including c.1,250–2,900 individuals of two Gyps species. We also present national population estimates for two species: White-backed Vulture (c.1,000–2,600 birds) and Lappet-faced Vulture (c.160–500 birds). Although sightings were assigned to only three broad distance bands, Distance sampling provided estimates with a level of precision similar to that achieved for linear encounter rates, but as density estimates; a form more readily comparable with results obtained from other survey types.

Estimating the density of Antarctic krill (Euphausia superba) from multi-beam echo-sounder observations using distance sampling methods

2011 ◽  
Vol 60 (2) ◽  
pp. 301-316 ◽  
Author(s):  
Martin J. Cox ◽  
David L. Borchers ◽  
David A. Demer ◽  
George R. Cutter ◽  
Andrew S. Brierley
Keyword(s):  
Antarctic Krill ◽  
Sampling Methods ◽  
Distance Sampling ◽  
Euphausia Superba ◽  
Antarctic Krill Euphausia Superba ◽  
Echo Sounder

Geodolite measurements near the Briones Hills, California, earthquake swarm of January 8, 1977

1978 ◽  
Vol 68 (1) ◽  
pp. 175-180
Author(s):  
J. C. Savage ◽  
W. H. Prescott
Keyword(s):  
Earthquake Swarm ◽  
Dislocation Model ◽  
Maximum Magnitude ◽  
Epicentral Area ◽  
Observable Change ◽  
Measuring Techniques ◽  
Significant Change ◽  
Tilt Change ◽  
Distance Measuring

abstract Two geodetic stations, the positions of which are frequently monitored by geodetic distance-measuring techniques, were located 5 and 10 km from the epicentral area of the Briones Hills earthquake swarm (maximum magnitude ML = 4.3) of January 1977. Although a 10 μradian postearthquake tilt change was recorded at a nearby tiltmeter, no significant change in geodetic distances could be detected at a sensitivity of at least 0.5 ppm. A simple dislocation model of the main earthquake in the swarm would predict no observable change in either tilt or geodetic distance.

scholarly journals Incorporating Availability for Detection in Estimates of Bird Abundance

The Auk ◽  
2007 ◽  
Vol 124 (1) ◽  
pp. 96-106 ◽  
Author(s):  
Duane R. Diefenbach ◽  
Matthew R. Marshall ◽  
Jennifer A. Mattice ◽  
Daniel W. Brauning
Keyword(s):  
Survey Methods ◽  
Distance Sampling ◽  
Sampling Period ◽  
Bird Abundance ◽  
Point Counts ◽  
Variance Estimators ◽  
Bird Survey ◽  
Detection Probabilities ◽  
Ammodramus Henslowii ◽  
Further Development

Abstract Several bird-survey methods have been proposed that provide an estimated detection probability so that bird-count statistics can be used to estimate bird abundance. However, some of these estimators adjust counts of birds observed by the probability that a bird is detected and assume that all birds are available to be detected at the time of the survey. We marked male Henslow's Sparrows (Ammodramus henslowii) and Grasshopper Sparrows (A. savannarum) and monitored their behavior during May-July 2002 and 2003 to estimate the proportion of time they were available for detection. We found that the availability of Henslow's Sparrows declined in late June to <10% for 5- or 10-min point counts when a male had to sing and be visible to the observer; but during 20 May-19 June, males were available for detection 39.1% (SD = 27.3) of the time for 5-min point counts and 43.9% (SD = 28.9) of the time for 10-min point counts (n = 54). We detected no temporal changes in availability for Grasshopper Sparrows, but estimated availability to be much lower for 5-min point counts (10.3%, SD = 12.2) than for 10-min point counts (19.2%, SD = 22.3) when males had to be visible and sing during the sampling period (n = 80). For distance sampling, we estimated the availability of Henslow's Sparrows to be 44.2% (SD = 29.0) and the availability of Grasshopper Sparrows to be 20.6% (SD = 23.5). We show how our estimates of availability can be incorporated in the abundance and variance estimators for distance sampling and modify the abundance and variance estimators for the double-observer method. Methods that directly estimate availability from bird counts but also incorporate detection probabilities need further development and will be important for obtaining unbiased estimates of abundance for these species. Incorporación de la Disponibilidad para la Detección en las Estimaciones de Abundancia de Aves

Erratum to: Distance Sampling: Methods and Applications

2017 ◽  
pp. E3-E4
Author(s):  
S. T. Buckland ◽  
E. A. Rexstad ◽  
T. A. Marques ◽  
C. S. Oedekoven
Keyword(s):  
Sampling Methods ◽  
Distance Sampling

Estimating western ringtail possum (Pseudocheirus occidentalis) density using distance sampling

2010 ◽  
Vol 32 (2) ◽  
pp. 197 ◽  
Author(s):  
G. R. Finlayson ◽  
A. N. Diment ◽  
P. Mitrovski ◽  
G. G. Thompson ◽  
S. A. Thompson
Keyword(s):  
Urban Development ◽  
Population Size ◽  
Western Australia ◽  
Distance Sampling ◽  
Reliable Estimate ◽  
Population Estimates ◽  
Density Estimates ◽  
The Subject ◽  
Ringtail Possum

A reliable estimate of population size is of paramount importance for making management decisions on species of conservation significance that may be impacted during development. The western ringtail possum (Pseudocheirus occidentalis) is regularly encountered during urban development and is the subject of numerous surveys to estimate its abundance. A variety of techniques have been used for this species with mixed results. This paper reports on a case study using distance sampling to estimate density of P. occidentalis in a small habitat remnant near Busselton, Western Australia. Density estimates obtained were within the range of previous studies of this species and we suggest that this technique should be employed in future surveys to improve the accuracy of population estimates for this species before development.

A SEVEN-YEAR COMPARISON OF RELATIVE-ABUNDANCE AND DISTANCE-SAMPLING METHODS

The Auk ◽  
2003 ◽  
Vol 120 (4) ◽  
pp. 1013 ◽  
Author(s):  
Russell E. Norvell ◽  
Frank P. Howe ◽  
Jimmie R. Parrish
Keyword(s):  
Relative Abundance ◽  
Sampling Methods ◽  
Distance Sampling

Distance Sampling: Methods and Applications

Bird Study ◽  
2016 ◽  
Vol 63 (1) ◽  
pp. 152-153
Author(s):  
Mark W. Miller
Keyword(s):  
Sampling Methods ◽  
Distance Sampling

scholarly journals Using mark-recapture distance sampling methods on line transect surveys

2014 ◽  
Vol 5 (11) ◽  
pp. 1180-1191 ◽  
Author(s):  
Mary Louise Burt ◽  
David L. Borchers ◽  
Kurt J. Jenkins ◽  
Tiago A. Marques
Keyword(s):  
Sampling Methods ◽  
Distance Sampling ◽  
Line Transect ◽  
Mark Recapture ◽  
On Line

scholarly journals A comparison of derived population estimate, mark-resighting and distance sampling methods to determine the population size of a desert ungulate, the Arabian oryx

Oryx ◽  
2003 ◽  
Vol 37 (03) ◽  
Author(s):  
Philip J. Seddon ◽  
Khairy Ismail ◽  
Mohammed Shobrak ◽  
Stephane Ostrowski ◽  
Chris Magin
Keyword(s):  
Population Size ◽  
Sampling Methods ◽  
Distance Sampling ◽  
Population Estimate ◽  
Arabian Oryx
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