Limits...
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.


Example showing how nest and brood monitoring data and a user‐defined nest interval (21 days), brood interval (21 days), renest interval (5 days), and postfledge interval were used to estimate breeding pairs. In this example, the postfledge interval extends from the time a brood fledged to the end of breeding season (EOBS) as the species in this hypothetical example did not renest after fledging a brood (blue bars extending to the right side of the renest interval). The gray shaded area indicates when the maximum numbers of breeding pairs (three) occurred. The vertical dashed blue lines represent a hypothetical sampling interval that occurred every 10 days. The breeding population estimator (BPE) assumes sampling occurs at sufficient regularity that the maximum number of breeding pairs can reliability be estimated.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4588649&req=5

ece31680-fig-0002: Example showing how nest and brood monitoring data and a user‐defined nest interval (21 days), brood interval (21 days), renest interval (5 days), and postfledge interval were used to estimate breeding pairs. In this example, the postfledge interval extends from the time a brood fledged to the end of breeding season (EOBS) as the species in this hypothetical example did not renest after fledging a brood (blue bars extending to the right side of the renest interval). The gray shaded area indicates when the maximum numbers of breeding pairs (three) occurred. The vertical dashed blue lines represent a hypothetical sampling interval that occurred every 10 days. The breeding population estimator (BPE) assumes sampling occurs at sufficient regularity that the maximum number of breeding pairs can reliability be estimated.

Mentions: A visual example of the requisite data is provided (Fig. 2).


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

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

Example showing how nest and brood monitoring data and a user‐defined nest interval (21 days), brood interval (21 days), renest interval (5 days), and postfledge interval were used to estimate breeding pairs. In this example, the postfledge interval extends from the time a brood fledged to the end of breeding season (EOBS) as the species in this hypothetical example did not renest after fledging a brood (blue bars extending to the right side of the renest interval). The gray shaded area indicates when the maximum numbers of breeding pairs (three) occurred. The vertical dashed blue lines represent a hypothetical sampling interval that occurred every 10 days. The breeding population estimator (BPE) assumes sampling occurs at sufficient regularity that the maximum number of breeding pairs can reliability be estimated.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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

ece31680-fig-0002: Example showing how nest and brood monitoring data and a user‐defined nest interval (21 days), brood interval (21 days), renest interval (5 days), and postfledge interval were used to estimate breeding pairs. In this example, the postfledge interval extends from the time a brood fledged to the end of breeding season (EOBS) as the species in this hypothetical example did not renest after fledging a brood (blue bars extending to the right side of the renest interval). The gray shaded area indicates when the maximum numbers of breeding pairs (three) occurred. The vertical dashed blue lines represent a hypothetical sampling interval that occurred every 10 days. The breeding population estimator (BPE) assumes sampling occurs at sufficient regularity that the maximum number of breeding pairs can reliability be estimated.
Mentions: A visual example of the requisite data is provided (Fig. 2).

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.