Grasshoppers do not flee from their alarmed predators but from non-alarmed ones

Alarm calls produced by basal prey have well-known informative value. In multipredator communities, mesopredators, when faced with top predators, may emit alarm calls that could inform basal prey about their lowered predation risk. To test this unexplored possibility, we conducted one field and one mesocosm experiment in which we simulated alarm and non-alarm calls from little owls (Athene noctua) as mesopredators and measured their effects on grasshoppers as prey of little owls but not of top predators. In the field experiment, we found that grasshopper species were significantly more abundant in patches where we simulated either the presence of scared little owls (alarm treatment) or no owls (control treatment) compared to patches where the presence of non-scared little owls (non-alarm treatment) was simulated. In the mesocosm experiment, locusts’ (Locusta migratoria) moved significantly more to exposed areas when we simulated the presence of scared little owls (alarm treatment) or of..., Firstly, in a field experiment we sampled the abundance of several grasshopper species in patches after broadcasting repeatedly for several days either little owls’ alarm calls (alarm treatment, simulating scared owls) or non-alarm/contact calls (non-alarm treatment, simulating non-scared owls), or just visiting the patches (control treatment, simulating no owls). In addition, in a mesocosm experiment, we recorded the distribution of migratory locusts (Locusta migratoria) in exposed and sheltered areas before and after broadcasting little owls´ alarm calls (alarm treatment), non-alarm/contact calls (non-alarm treatment) or vocalizations of a woodpigeon (Columba palumbus) as a granivorous, non-predator bird for grasshoppers (control treatment).
The abundance of grasshoppers in the field experiment were sampled in all patches by counting all detected individuals, either inactive or during their flights/jumps, while walking at constant speed (about 2 km per hour) along longitudinal transec..., , # Grasshoppers do not flee from their alarmed predators but from non-alarmed ones

[https://doi.org/10.5061/dryad.tht76hf7c](https://doi.org/10.5061/dryad.tht76hf7c)

We provide data obtained in a large-scale field experiment (**first sheet**) and in a mesocosm experiment (**second sheet**) to study the response of grasshoppers to different calls of their predators.

#### **Description of the data and file structure**

In the first sheet, we provide the data extracted from the Field experiment. Variables used were:

**Transect_ID** = Identification of the transect

**Patch**= Experimental patch

**Treatmen**t =Call treatment as Alarm, Non-alarm or Control

**Julian_date** = date expressed as the number of days since the first of January

**Juliandate_class** = classification of the transects as early or late according to whether they were carried out before or after the median date value

**Grasshoppers_abundance** = Number of counted grasshoppers per transect

**Size**(m2) = Patch size...