In Argentina, no dietary studies had been conducted on White-tailed Kites (Elanus leucurus) until Leveau et al. (2002, Ornitol. Neotrop. 13:307–311). In a recent issue of the Journal, Leveau et al. (2004, J. Raptor Res. 38:178–181) published a second report on the diet of White-tailed Kite for Argentina, a comparison of prey with that of the Barn Owl (Tyto alba).
I compared the dietary samples contained in both papers and determined that some of the data in the Journal of Raptor Research article were previously published by the authors. Both studies were conducted in the same area of Argentina (Villa Cacique, Buenos Aires Province, 37°40′S, 59°23′W), the dates for sample collection were similar (August to November of 1998 and August to December 1998 for Leveau et al. 2002 and 2004, respectively) and the sample sizes were the same (77 pellets). The authors did not acknowledge that the diet data used in the second paper (Leveau et al. 2004) were the same as previously published (Leveau et al. 2002).
Because the second paper included a comparison of White-tailed Kite diet to an owl diet, the authors may have considered the second paper as a different analysis of previously-collected and published data, a legitimate research approach, as data on food habits of the two species came from the same habitat and locality. The use of previously-published data may be necessary when reviewing geographical patterns of food habits or studying bird assemblages in a given area. Bibliographic sources consulted or information reproduced should be adequately acknowledged independent of the authorship of the previous studies. Readers of both journals, as well as researchers reviewing existing literature on the food habits of White-tailed Kites, must then be cautioned to consider the information from only one of these papers as representative of the diet of White-tailed Kites for the habitat described by the authors of these reports.
I want to thank Juan José Negro, Michael Goldstein, Kim Titus, and two anonymous reviewers for helpful comments that greatly improved this manuscript.