Context. In many countries, annual wolf surveys based on snow-track counts have become unreliable because of inconsistent snow coverage. We considered incidental observations by volunteers throughout the year as an alternative monitoring protocol.

Aims. We recruited interested citizens throughout Lithuania, including hunters, foresters and farmers, to estimate wolf distribution, abundance, pack numbers and group size from 2015 to 2018.

Methods. Observation-based records of wolves were collected using simple questionnaires that included time, location and method of observation (e.g. track, scat, vocalisation or prey-kill remains). We summarised 979 reports of 1938 observed wolves.

Key results. Volunteer reports suggested an increase in wolf distribution and abundance from 2015 to 2018. The observed number of wolf packs was estimated to be at least 100 by 2018, pack size increased to 3.6, and the share of single wolves decreased from 56% in 2015 to 40% in 2018.

Conclusions. We found that volunteer observations can provide useful information on wolf distribution, pack size and pack numbers. Our results support previous reports of expanding wolf populations in the Baltic region.

Implications. Results of our citizen-science effort by Nature Research Centre and Lithuanian Hunters and Fishers Association have been accepted by the Ministry of Environment as a complement to other surveys in Lithuania and should aid in developing an informed wolf-management policy.