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A comparison of breeding population estimators using nest and brood monitoring data.

Baasch DM, Hefley TJ, Cahis SD - Ecol Evol (2015)

Bottom Line: Based on our simulated data, we expect our BPE to be closest to the true number of breeding pairs as compared to other methods.The methods tested resulted in substantially different estimates of the numbers of breeding pairs; however, coefficients from trend analyses were not statistically different.When data from multiple nest and brood surveys are available, the BPE appears to result in reasonably precise estimates of numbers of breeding pairs.

View Article: PubMed Central - PubMed

Affiliation: Headwaters Corporation 4111 4th Avenue Suite 6 Kearney Nebraska 68845.

ABSTRACT
For many species, breeding population size is an important metric for assessing population status. A variety of simple methods are often used to estimate this metric for ground-nesting birds that nest in open habitats (e.g., beaches, riverine sandbars). The error and bias associated with estimates derived using these methods vary in relation to differing monitoring intensities and detection rates. However, these errors and biases are often difficult to obtain, poorly understood, and largely unreported. A method was developed to estimate the number of breeding pairs using counts of nests and broods from monitoring data where multiple surveys were made throughout a single breeding season (breeding pair estimator; BPE). The BPE method was compared to two commonly used estimation methods using simulated data from an individual-based model that allowed for the comparison of biases and accuracy. The BPE method underestimated the number of breeding pairs, but generally performed better than the other two commonly used methods when detection rates were low and monitoring frequency was high. As detection rates and time between surveys increased, the maximum nest and brood count method performs similar to the BPE. The BPE was compared to four commonly used methods to estimate breeding pairs for empirically derived data sets on the Platte River. Based on our simulated data, we expect our BPE to be closest to the true number of breeding pairs as compared to other methods. The methods tested resulted in substantially different estimates of the numbers of breeding pairs; however, coefficients from trend analyses were not statistically different. When data from multiple nest and brood surveys are available, the BPE appears to result in reasonably precise estimates of numbers of breeding pairs. Regardless of the estimation method, investigators are encouraged to acknowledge whether the method employed is likely to over- or underestimate breeding pairs. This study provides a means to recognize the potential biases in breeding pair estimates.

No MeSH data available.


Photograph of interior least terns and a piping plover fledgling.
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ece31680-fig-0001: Photograph of interior least terns and a piping plover fledgling.

Mentions: For threatened or endangered birds, breeding population size is an important metric for assessing recovery of the species. If the method(s) used to estimate the size of breeding populations are not well documented, population estimates may be dissimilar and not comparable across subpopulations or within a single population over time. For example, several recovery plans, biological opinions, monitoring protocols, and reports focused on endangered interior least terns (Sternula antillarum athalassos; least tern) and threatened piping plovers (Charadrius melodus) recommend estimating the numbers of breeding pairs within localized areas where nesting occurs (hereafter “subpopulations”; Fig. 1). In these documents, methods for estimating the number of breeding pairs in the subpopulations included a range of methods, but no specific recommendations (Hecht and Melvin 2009; Environment Canada 2013; Shaffer et al. 2013); included multiple methods to be employed within or between nesting seasons and therefore may not be comparable across nesting seasons (Platte River Recovery Implementation Program [Program] 2011; Frost 2013; Shaffer et al. 2013); appear to exclude renesting or other pertinent information (Shaffer et al. 2013); or, in a large number of cases, were not defined and left to be chosen by the investigator (U.S. Fish and Wildlife Service [USFWS] 1988, 1989, 1990, 1996, 2003, 2006, U.S. Army Corps of Engineers [USACE] 1993, 1999, Whitfield et al. 1996, Lutey 2002; Boettcher et al. 2007). Recovery plans for other ground‐nesting bird species appear to suffer from similar ambiguities (Reed and Murray 1993; Department of Environment and Climate Change NSW 2008; Florida Fish and Wildlife Conservation Commission 2013).


A comparison of breeding population estimators using nest and brood monitoring data.

Baasch DM, Hefley TJ, Cahis SD - Ecol Evol (2015)

Photograph of interior least terns and a piping plover fledgling.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4588649&req=5

ece31680-fig-0001: Photograph of interior least terns and a piping plover fledgling.
Mentions: For threatened or endangered birds, breeding population size is an important metric for assessing recovery of the species. If the method(s) used to estimate the size of breeding populations are not well documented, population estimates may be dissimilar and not comparable across subpopulations or within a single population over time. For example, several recovery plans, biological opinions, monitoring protocols, and reports focused on endangered interior least terns (Sternula antillarum athalassos; least tern) and threatened piping plovers (Charadrius melodus) recommend estimating the numbers of breeding pairs within localized areas where nesting occurs (hereafter “subpopulations”; Fig. 1). In these documents, methods for estimating the number of breeding pairs in the subpopulations included a range of methods, but no specific recommendations (Hecht and Melvin 2009; Environment Canada 2013; Shaffer et al. 2013); included multiple methods to be employed within or between nesting seasons and therefore may not be comparable across nesting seasons (Platte River Recovery Implementation Program [Program] 2011; Frost 2013; Shaffer et al. 2013); appear to exclude renesting or other pertinent information (Shaffer et al. 2013); or, in a large number of cases, were not defined and left to be chosen by the investigator (U.S. Fish and Wildlife Service [USFWS] 1988, 1989, 1990, 1996, 2003, 2006, U.S. Army Corps of Engineers [USACE] 1993, 1999, Whitfield et al. 1996, Lutey 2002; Boettcher et al. 2007). Recovery plans for other ground‐nesting bird species appear to suffer from similar ambiguities (Reed and Murray 1993; Department of Environment and Climate Change NSW 2008; Florida Fish and Wildlife Conservation Commission 2013).

Bottom Line: Based on our simulated data, we expect our BPE to be closest to the true number of breeding pairs as compared to other methods.The methods tested resulted in substantially different estimates of the numbers of breeding pairs; however, coefficients from trend analyses were not statistically different.When data from multiple nest and brood surveys are available, the BPE appears to result in reasonably precise estimates of numbers of breeding pairs.

View Article: PubMed Central - PubMed

Affiliation: Headwaters Corporation 4111 4th Avenue Suite 6 Kearney Nebraska 68845.

ABSTRACT
For many species, breeding population size is an important metric for assessing population status. A variety of simple methods are often used to estimate this metric for ground-nesting birds that nest in open habitats (e.g., beaches, riverine sandbars). The error and bias associated with estimates derived using these methods vary in relation to differing monitoring intensities and detection rates. However, these errors and biases are often difficult to obtain, poorly understood, and largely unreported. A method was developed to estimate the number of breeding pairs using counts of nests and broods from monitoring data where multiple surveys were made throughout a single breeding season (breeding pair estimator; BPE). The BPE method was compared to two commonly used estimation methods using simulated data from an individual-based model that allowed for the comparison of biases and accuracy. The BPE method underestimated the number of breeding pairs, but generally performed better than the other two commonly used methods when detection rates were low and monitoring frequency was high. As detection rates and time between surveys increased, the maximum nest and brood count method performs similar to the BPE. The BPE was compared to four commonly used methods to estimate breeding pairs for empirically derived data sets on the Platte River. Based on our simulated data, we expect our BPE to be closest to the true number of breeding pairs as compared to other methods. The methods tested resulted in substantially different estimates of the numbers of breeding pairs; however, coefficients from trend analyses were not statistically different. When data from multiple nest and brood surveys are available, the BPE appears to result in reasonably precise estimates of numbers of breeding pairs. Regardless of the estimation method, investigators are encouraged to acknowledge whether the method employed is likely to over- or underestimate breeding pairs. This study provides a means to recognize the potential biases in breeding pair estimates.

No MeSH data available.