02273nas a2200205   4500008004100000245010700041210006900148520160100217653001601818653001801834653002001852653001401872653002901886653001601915653001701931653002901948100002301977700002302000856004402023       2020                        eng d00aDoes the presence of an observer affect a bird's occurrence rate or singing rate during a point count?0 aDoes the presence of an observer affect a birds occurrence rate 3 a<p>The approach or presence of an observer may affect the behavior of nearby birds, rendering them either more or less detectable than when no observer is present due to a change in singing rates. To test whether there are systematic detection biases associated with the presence of an observer during point count bird surveys, we compared the occurrence and singing rates of birds during a 10‐min period immediately preceding the time when an observer arrived to conduct a count and during the formal count itself by extracting song information from autonomous sound recorders. We obtained recordings of 36 species of birds detected at &ge;5 locations in one of three vegetation types, including burned conifer forest, green conifer/riparian streamside forest, and riparian bottomland/marshland. We found that species richness and both the probability of occurrence and singing rate for any of the species recorded were unaffected by the presence of an observer. In addition, the probability of occurrence did not differ significantly among four 2.5‐min recording sessions during 10‐min counts when an observer was present. Thus, the presence of an observer did not appear to introduce any detectable systematic bias that would make bird lists or unadjusted occurrence rates inaccurate on that basis alone. In addition, rates of bird occurrence across 2.5‐min temporal subsets of a 10‐min count did not vary in a systematic way that would violate the assumption of equal occupancy across adjacent time periods as sometimes used to build detection histories in occupancy modeling.</p>
10abird survey10adetectability10aobserver effect10aoccupancy10apassive acousticsampling10apoint count10asinging rate10autonomous recording unit1 aHutto, Richard, L.1 aHutto, Russell, R.  uhttp://doi.wiley.com/10.1111/jofo.1232902126nas a2200241   4500008004100000022001300041245005900054210005800113260001600171300001200187490000800199520128200207653001301489653001901502653001401521653002101535653002501556653001901581653001101600100001801611700002201629856023301651       2019                        eng d  a0003347200aContext-dependent variation of house finch song syntax0 aContextdependent variation of house finch song syntax  cJan-01-2019  a33 - 420 v1473 a<p>We explored the role of social context in the syntactical variation of house finch, Haemorhous mexicanus, songs using both traditional song measures and network analysis. In comparison to solo bouts, the bouts of countersinging males had increased syntax diversity, with higher numbers of simple paths and transition types (but not syllable types) in comparison to solo song, which had high sequence consistency. Both the proportion of introductory syllables and the degree (number of transitions to and from those syllables) increased in countersinging bouts and were an important source of syntactic variability. In contrast, courtship bouts included longer songs and longer syllables than both solo and countersinging bouts, but were similar to solo songs in sequence consistency. The longest courtship songs often included concatenated sequences that formed &lsquo;compound songs&rsquo;, or repeating strings of main song syllables, which slightly increased the degree of those syllables. Our results suggest that interactions between males are associated with increased syntactic variability in song delivery while female choice favours signals that maintain species-typical syntax and demonstrate fitness in terms of a male&#39;s capacity to sing extended songs.</p>
10abirdsong10acountersinging10acourtship10anetwork analysis10asequence consistency10asocial context10asyntax1 aCiaburri, Ivy1 aWilliams, Heather  uhttps://linkinghub.elsevier.com/retrieve/pii/S0003347218303373https://api.elsevier.com/content/article/PII:S0003347218303373?httpAccept=text/xmlhttps://api.elsevier.com/content/article/PII:S0003347218303373?httpAccept=text/plain