Abundance and diversity of small-bird assemblages in the Monte desert, Argentina

The use of the point count method for bird survey in the Atlantic forest

“…The plasticity on resources used by omnivores may have influenced this result: wide habitat dispersal could have been an important factor for the decreasing probabilities of omnivorous birds recording during non-breeding season in the present study (CATTERALL et al 1998, VAN HEEZIK & SEDDON 1999, BLENDINGER 2005, MOORMAN et al 2007, LOPEZ DE CASENAVE et al 2008.…”

“…However, MOF and DOF showed decrease on bird species and abundance per point count in the non-breeding season; in SSF these results were not significantly different between seasons. The lower frequency of birds vocalization during the non-breading season is considered one reason for the low probability of record them during this season ( VAN HEEZIK & SEDDON 1999, PAGEN et al 2002, besides the seasonal modification in habitat use and in functional groups (BLENDINGER 2005, BOWEN et al 2007, LOPEZ DE CASENAVE et al 2008. Considering this, changes in the detection of bird species using the point count during non-breeding season would be expected also in SSF (ANTUNES 2008).…”

Does the reproductive season account for more records of birds in a marked seasonal climate landscape in the state of São Paulo, Brazil?

“…When analyzing families with more than 150 detections, only one (Tyrannidae) tended to be more detectable during breeding counts (Table 2). If summer migrants were removed from this analysis, this family Blendinger, 2005;Volpato et al, 2009), then they should have been recorded more during the breeding season due to an increase in abundance with the fledging of young birds, or increase in detections due to more conspicuous vocalization during this period (Freifeld et al, 2004). However, overall detections were actually slightly greater during the nonbreeding season at UNESP, and many differences between monthly empirical values of species richness and abundance were negative at both study areas.…”

“…Neotropical habitats, however, have not been the scope of these evaluations (e.g., Hutto et al, 1986;Blake, 1992;Lynch, 1995;Esquivel & Peris, 2008). It has been proposed that counts of birds can vary seasonally according to forest type and functional groups, whereas a trend in decreasing detections can be observed throughout the day (Herzog et al, 2003;Blendinger, 2005;Isacch et al, 2006;Brandolin et al, 2007;Antunes, 2008;Volpato et al, 2009). Although there is increasing literature on variations of bird detections, a clear consensus on when and how to survey Neotropical birds is still far from being achieved.…”

“…This typical approach has been poorly demonstrated in Neotropical habitats (Blendinger, 2005;Brandolin et al, 2007;Antunes, 2008;Volpato et al, 2009); in the Cerrado, for example, a tropical savanna with seasonal rainfall, only hourly counts of birds have been examined (Cavarzere & Moraes, 2010). Determining successful protocols for surveying birds is a priority as many studies use counting techniques with no a priori tests regarding method efficiency or habitat type.…”