Q: Does someone who has collected part of the data for my study merit co-authorship?

Two researchers and I meet all of the authorship criteria for a paper on a topic in ecology, with me serving as lead author. We three conceived and designed the study, secured funding, implemented and led data collection, conducted all data analyses, interpreted results, and wrote the entirety of the manuscript. We are all appropriately listed on the by-line as authors, and we have agreed to the contents of the manuscript.

Two other researchers (A and B) contributed to data collection for our study. Researcher A was simultaneously conducting a separate study on the same focal species as us, for which Researcher A enlisted Researcher B to conduct all of the data collection. We also enlisted Researcher B to assist with data collection for our study. Researcher B collected a notable portion of the data that we used in our analysis, but provided no contributions to any other portion of our study. Researcher A provided us with some of the unpublished data that were collected as part of his separate but simultaneous study, but similarly provided no contributions to any other portion of our study.

After completing data analysis and writing of the manuscript, I asked the two other definitive authors if they thought the contributions to data collection by Researchers A and B were sufficient to warrant offering co-authorship on our paper. Both authors stated that the decision was up to me as lead author. Given Researcher B collected a notable portion of the data that we used in our study, I believed that offering Researcher B authorship by providing the opportunity to contribute intellectually to the paper via reviewing and providing edits/comments was appropriate. I emailed Researcher B the draft manuscript, stated that I was offering the opportunity to make additional contributions for co-authorship, but that I needed a decision within one week on whether B accepted or declined the offer. I also requested that Researcher B not share the manuscript with anyone, since Researcher B was technically not an author yet, and I asked Researcher B his opinion on whether Researcher A's contributions merited an offer of co-authorship.

Researcher B responded that offering Researcher A co-authorship was "probably the polite thing to do," and that he would give me his decision on my offer to him within one week as I had requested. Researcher B subsequently sent me a disgruntled email the following day stating that he had discussed the manuscript with Researcher A, who asked Researcher B to send a copy of the manuscript and expressed concerns with submitting the manuscript for publication. Researcher B stated that he did not like keeping a paper from an author who has requested it, that there was no need for secrecy, alleged that I had ignored his suggestion to add Researcher A as an author, and recommended that I contact Researcher A immediately.

I responded to Researcher B, reiterating that my email with draft manuscript was an offer for him to additionally contribute and earn authorship. As such, and because he had not provided me a decision on the offer, he was technically not an author yet and should not have discussed the manuscript with anyone, including Researcher A. I also explained to Researcher B that since he was not an author yet, the decision on whether or not Researcher A should also be offered co-authorship was not up to him, and that I had not yet had time to discuss such an offer with the two other definitive authors of the manuscript. I have not received a response to this from Researcher B, nor have I been contacted by Researcher A. I forwarded the email exchange with Researcher B to the two other definitive authors to apprise them of the situation.

At this point, I am unsure what the appropriate course of action is. My offer of authorship to Researcher B was, in my opinion, a generous one. Researcher B's actions and statements following that offer, however, have caused me to question whether such generosity was actually warranted or should instead now be retracted. Additionally, I am perplexed as to why Researcher B would imply that Researcher A's contributions did not warrant an offer of co-authorship (i.e., "the polite thing to do"), which supported my initial thoughts, but then subsequently discuss the manuscript with Researcher A and assume that A was automatically an author and deserved to see a copy of the manuscript.

I am not a novice to publishing research or collaborating on studies, and having a couple of extra co-authors on a paper is not a big deal, assuming those co-authors sufficiently contribute and meet the criteria for authorship. However, I have never encountered the issues that exist in this particular situation. I have little doubt that if the offer of authorship to Researcher B is retracted and Researcher A is not offered authorship, both will likely file a complaint with the prospective journal's Editorial Board. Researcher B would claim that he was inappropriately excluded from the author list because he contributed to data collection and reviewed a single draft, and Researcher A could make a similar claim because a small portion of the data that we used in our study were collected as part of Researcher A's study (collected by Researcher B, though).

Thus, my specific questions are:

1) Should my offer of authorship to Researcher B be retracted as a consequence of his unjustified, and possibly unethical, actions and statements?

2) Does Researcher A deserve an offer of authorship for providing some data that were collected as part of his study, despite not contributing to other portions of our study?

I would very much appreciate any suggestions for resolving this issue and appropriate courses of action.

Thank you.