Howling activity of free-ranging wolves (Canis lupus) in the Bialowieza Primeval Forest and the Western Beskidy Mountains (Poland)

We investigated spontaneous howling by radio-collared wolves Canis lupus inhabiting the Bialeowieza Primeval Forest (BPF), eastern Poland, and elicited howling behavior in wolves of the BPF and the Western Beskidy Mountains, southern Poland. Over half (58%) of all spontaneous howls recorded throughout a year occurred in the period from July to October, with a peak in August. The daily pattern of vocal activity by wolves was characterised by a peak between 1800 and 0000 hours, which coincided with the first (dusk) peak of wolf mobility. Wolves howled from the core areas of their territories and not from the peripheries. Howls served as communication between temporarily separated pack mates (43% of cases), after re-union (18%) and before setting out for a hunt (22%). Very few spontaneous howls (2%) were targeted at a neighbouring pack. Wolves responded to human-simulated howling in June-September, with a peak in August (reply rate: 39%). The duration of elicited howling increased significantly with group size: howls by single wolves or pairs lasted, on average, 34-40 s, whereas those of five to seven wolves (including pups) had an average duration of 67-95 s, with a maximum length of nearly 4 min. In the populations of Polish wolves studied here, spontaneous howling served primarily for intra-pack communication. Nonetheless, the high reply rate to howling simulation showed that - if necessary - wolves readily advertised their presence in a territory to strangers.