In the following manuscript an interesting and very efficient method is proposed, because an integrated methodology of sampling, rarefaction and extrapolation is proposed to compare the species richness of a set of communities based on samples of equal integrity (as measured by the coverage sample) instead of equal size. This method produces less biased comparisons of wealth between communities, and manages it with a smaller total sampling effort. In the work hypothetical and real examples are proposed to demonstrate these advantages.

Chao, A., & Jost, L. (2012). Coverage‐based rarefaction and extrapolation: Standardizing samples by completeness rather than size. Ecology, 93(12), 2533-2547.

http://googleweblight.com/i?u=http://onlinelibrary.wiley.com/doi/10.1111/j.1474-919X.2001.tb04942.x/full&grqid=qCaShlB-&hl=en-IN

http://googleweblight.com/i?u=http://onlinelibrary.wiley.com/doi/10.1111/j.1474-919X.2001.tb04942.x/full&grqid=qCaShlB-&hl=en-IN

Ramesh, Thanks, this is helpful, But It doesn't answer my second question that we wheater we should do separate curves for resident and migratory or not?

Since you use the same transect, you must use the mean (with SE) of the estimates. The species accumulation curve is also a very nice way of exemplifying species richness. I think you could do both types of curves as long as you specify their composition in the captions :) 

It will depend of course on what you intend to use your data for. If your are making statistical comparisons between sites, mean and SE measures are useful. But those statistical measures assume that each species in the population of species has an equal probability of being included in each sample, and we know that this is not true of bird surveys (species differ in their detectability). Thus species accumulation curves can provide a better estimate of the "true" value of species richness, and can also be used to compare richness between sites when the same number of transects are conducted. And you could look at the species accumulation curves of migrants and residents to see if they should be grouped together into a single mean estimate.

The answers are good, I would separate migrant residents and be careful with singletons and doubletons in my analysis

This discussion is a bit naive. For species, like birds, that move through the landscape, even when tied down to a breeding territory or nest site, there's no such thing as a standard "species richness". Season is clearly one influence on richness, as migrants come and go. Each season will include some species and exclude others, so there is no one best season, nor status of species; it depends on what is the purpose of the study. Nor is richness necessarily a good measure of the quality of a site, as it subsumes many species, each with its own ecology and status, into one measure. So, you need to ask first: why measure richness, rather than some other aspect(s) of the bird "community"? If you must measure richness, there's an extensive literature on estimation and one lesson there is that standardised effort does not suffice to compare places, as average detectability can differ between places (e.g. from differing habitat structure) and species, so that the return per unit effort can differ and the species accumulation curves can have quite different slopes. Methods that examine the increment of extra species as effort accumulates and standardise to some rate of accumulation are therefore preferable.

As for David Dawson's comments. Bird communities are seasonally diverse and this needs to be taken into account if comparing the dynamics of the sites/habitats. There are also other factors such as resident (and probably highly territorial species) that, if inquisitive will follow the observer along the transect (and more than likely be recorded more than the one time per survey). There are other issues relating to the visibility of the observer, their skill levels, etc.

A sampling unit (i.e., a survey) will only provide information to assess the relative abundance and diversity of a subset of the bird population. Therefore, it is not so much the numbers that are recorded that are of importance but the relative distribution of abundance.

For example. We undertake timed area searches in our surveys. We rotate the time we undertake the survey at each site over a 7 day period. At the end of that survey we collate the data but we only use the maximum number observed of a species on any one day for that survey period. These surveys are generally carried out on three separate occasions to incorporate seasonal variability. The only time all of the records for all surveys are combined is to provide an assemblage list for each of the sites. Other analyses are strictly contained within the hierarchy of seasonality.

Species accumulation curves are of limited use because the process assumes quite a lot about population distributions and variability. If you are wedded to the method I would suggest, again, to maintain the seasonal separation (this will accommodate you concern about migratory species and it has to be assumed that they are likely to be present for that specific period every year). If you wish to compare diversity measures within sites, compare diversity between seasons. If you would like to look at differences between sites, look at something like ANOSIM, SHE analysis , etc. You can also compare sites using persence/absence data in a hierarchical clustering technique (again, comparing within seasons) using appropriate binary distance measures.

Good luck in you analysis.

Richness of a community depend also of the total abondance of individuals.  Thus you may need rarefaction cuves to compare two communities. See FC James 1981 for birds ("Rarefaction, relative abondance, and diversity of avian communities. The Auk 98 : 785-800).

I still wonder, why study "richness" in the first place?

Leaving that asisde. The James 1981 method is well-known and often used. Standardizing effort is another method, but both fail on the two issues that I noted in my earlier comment.

Why multiple survey of one site, think of using seperate site in your study.

Depending on your objectives of course, yes consider seasonal aspects (migrator, breeding), frequency of occurrence, species assemblages and/or species area .... use the different aspects as metrics in describing your site, identify protected species .... describe any limitations and habitat that might influence your results. Good information for managers.

Just an additional thought. The species accumulation curve is an estimate of species within assemblages (that's the premise, anyway). If you want to look at survey effort, you have to consider each survey event as distinct and independent of other events. You can then determine the efficiency of your survey by plotting the number of new species added for each day of the event. If the trend of the line is still increasing by the end of the survey period and your species accumulation curve for that event tells you that the curve has not yet leveled off, then your survey effort is not capturing most of the species present. However, if both the species accumulation curve and the survey effort curve level off with similar species numbers, your survey effort is adequate. This is a little trick we have developed over many years of work in monitoring sites. As a result we have created a very robust species list for all groups and each season and know if something is afoot if we are not replicating those accumulation and survey effort curves.

In ecosystems there is no one answer, no universal model that is capable of capturing all the dynamics. Investigations only ever describe a moment in time and space.

It would be appropriate to know what was the time scale for those 100 surveys; if these are long years's data, the climate change aspect can be used as tool, and if that is linked with seasonality, the surveys become more useful. Beyond species richness, especially in case of taking over 100 surveys of the same site, you may try monitoring some of the rare species and /or some very common species.

In the following manuscript an interesting and very efficient method is proposed, because an integrated methodology of sampling, rarefaction and extrapolation is proposed to compare the species richness of a set of communities based on samples of equal integrity (as measured by the coverage sample) instead of equal size. This method produces less biased comparisons of wealth between communities, and manages it with a smaller total sampling effort. In the work hypothetical and real examples are proposed to demonstrate these advantages.

Chao, A., & Jost, L. (2012). Coverage‐based rarefaction and extrapolation: Standardizing samples by completeness rather than size. Ecology, 93(12), 2533-2547.

Thanks all,

Just an addition to all wonderful answers, I found this piece of writing very interesting.

https://terrestrialecosystems.com/misuse-and-abuse-of-data-analysis-in-biological-surveys-what-is-a-species-accumulation-curve-and-what-does-it-mean/