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Anthropogenic noise is spreading worldwide and can interfere with the acoustic communication of multiple animal groups. Species communicating in low-frequency ranges (having large sound production structures) and with limited vocal learning are expected to be especially vulnerable to human noise-induced masking interference. Yet how such species may confront this emerging impact has scarcely been explored. Here we examined the effect of anthropogenic noise on the calling behaviour of a sizeable non-passerine bird, the Little Bustard Tetrax tetrax, across a gradient of road traffic noise and in relation to male position within the lek. Using directional recordings and noise mapping, we determined inter– and intra-individual variation in call parameters and their relationship with noise level and frequency at both spatial and temporal scales, defined respectively as (i) variation of noise according to the position of the calling sites of each male within the lek (spatial scale) and (ii) fine temporal variation of noise experienced by individual males immediately prior to each call (temporal scale). Little Bustard males increased their call rate at sites exposed to higher average noise levels and at those located further from the nearest neighbour within the lek, whereas temporal changes in noise showed no effect on call rate. In contrast, call duration decreased with relative increases in noise level prior to each call, being unaffected by spatial changes in noise. Peak call frequency showed no significant variation over time and among sites. Our findings reveal that, despite its supposedly limited vocal learning, this species seems to exhibit fine-scale vocal adjustment, which implies some capacity to cope with anthropogenic noise. However, the lack of frequency shift suggests behavioural constraints that may compromise communication as the species uses low-pitched calls. This study provides insights into how some non-passerine birds may adjust their vocal sexual display to anthropogenic noise.—Barrero, A., Llusia, D., Traba, J., Iglesias-Merchan, C. & Morales, M.B. (2021). Vocal response to traffic noise in a non-passerine bird: the Little Bustard Tetrax tetrax. Ardeola, 68: 143-162.

Audio recording systems coupled with automated song recognition are commonly being used for monitoring wildlife. Recorders usually differ in cost and effectiveness, and their performance may vary with source distance, wind speed and acoustic source direction, among other factors. We here assess the cost-effectiveness of five audio systems considering such factors as distance and singing direction. We developed field tests using playback of Dupont's Lark Chersophilus duponti songs from nine fixed locations at distances of 1 to 256m, played towards or away from the recorders' position. We selected this species because its very characteristic song should be easily identified by automated signal recognition software. Field tests were carried out during March 2016 in level dwarf-shrub steppe (mean height < 40cm) in NE Spain. We found large differences in effectiveness between recorders. The number of songs detected by an automated signal recognition algorithm significantly decreased with distance and when playback was angled away from the recorder position, a factor never previously tested. Finally, we give the design of a cost-effective Autonomous Recording Unit, based upon the most effective recorder. We recommend researchers working with acoustic recorders to evaluate the performance of several devices before making a selection for long-term monitoring programmes, and to consider such factors such as singing direction in their analyses. —perez-Granados, C., Bota, G., Giralt, D., Albarracin, J. & Traba, J. (2019). Cost-effectiveness assessment of five audio recording systems for wildlife monitoring: differences between recording distances and singing direction. Ardeola, 66: 311-325.

Summary.We describe the use of different agricultural habitat types by little bustard females nesting and rearing young chicks, based on observations gathered over a five-year period (2001–2005) in central Spain. The frequency of occurrence of nest or family locations within male lekking territories is also evaluated, as well as their association to habitat types preferred by females for nesting or chick rearing. A total of 28 nesting or brood locations (19 nests plus 9 families) were recorded over the study period. Habitat use did not differ significantly between nesting females and families. Both for the total sample (nests plus families) and the only-nests sample, the frequency of recorded locations differed between agricultural habitat types, with long-term fallows (older than two years) being the most frequently used. Young fallows (1–2 years old) were significantly more frequently used than cultivated habitats and ploughed-fields together, but less than long-term fallows in both samples. Nest plus f...

Summary. This study describes the climatic factors determining the distribution of two sympatric steppe birds, the little and the great bustards, on a Western Palearctic scale. We used the European Bird Census Council breeding bird atlas, recording presence/absence for 50×50 km UTM squares. Climate data were extracted from a 10′ latitude × longitude global compilation. Linear and quadratic terms were included to account for non-linear responses. A model-averaging approach was performed to determine the weight and effect of those variables describing the climatic preferences for each species. Although both showed a preference for drier areas in Europe, our results suggest that the great bustard's climate niche is mainly defined by variables related to primary production (e.g. rainfall, soil moisture), with temperature-related variables being less influential. These results contrast with those for the little bustard, whose climate niche seems to be defined by both temperature and precipitation-related varia...