Frequently asked questions

What do LCI and UCI stand for?

LCI and UCI indicate the lower and upper confidence interval for abundance estimates.

How does abundanceR treat repeated visits to the same site during the same year?

The program treats every count as independent. This means that it treats a single visit to two points in the same way as it treats two visits to the same point. This is a common approach to dealing with repeated visits when estimating abundance. However, due to the potential for statistical dependence when visiting points multiple times in a year, the confidence intervals produced by abundanceR maybe be slightly smaller than the true confidence intervals when points are surveyed more than once a year.

What if I want to look at the effect of a variable (e.g., canopy cover) on bird abundance?

The program can only compare groups of points based on point groupings. However, you can group points based on a variable of interest. For example, you could select points with low canopy cover values (e.g., 0-30%) in the first group, medium in the second (e.g., 31-60%), and high (61-100%) in the third.

How do I convert abundance (birds per survey) into density (birds/area)?

To convert abundance (birds per survey) into birds/area, you need to know the area of the count circle. The Knutson (2008) protocol uses a 100 m radius count circle. This is equivalent to an area of 3.14 ha. To calculate density in birds/ha you divide the birds/survey by 3.14. These calculations can be done after you download the output file.

How can I tell if two groups are significantly different?

Use the lower and upper confidence intervals (LCI and UCI) to see if species abundance estimates are significantly different between groups. If the confidence intervals do not overlap, the abundance is significantly different. For example, if you want to be 90% certain that there are more Eastern Meadowlarks (EAME) in 2008 than there were in 2009, you would check to see if the 90% lower confidence interval (LCI) for 2008 is greater than the 90% upper confidence interval (UCI) for 2009.

What if I don't have a copy of Microsoft Access installed on my computer?

Not a problem! AbundanceR can read the Access datafile even if Microsoft Access is not installed on the computer.