*Article* **Austrian COLOSS Survey of Honey Bee Colony Winter Losses 2018/19 and Analysis of Hive Management Practices**

#### **Hannes Oberreiter and Robert Brodschneider \***

Institute of Biology, University of Graz, Universitätsplatz 2, 8010 Graz, Austria; hoberreiter@gmail.com **\*** Correspondence: robert.brodschneider@uni-graz.at; Tel.: +43-316-380-5602

Received: 7 February 2020; Accepted: 10 March 2020; Published: 13 March 2020

**Abstract:** We conducted a citizen science survey on overwinter honey bee colony losses in Austria. A total of 1534 beekeepers with 33,651 colonies reported valid loss rates. The total winter loss rate for Austria was 15.2% (95% confidence interval: 14.4–16.1%). Young queens showed a positive effect on colony survival and queen-related losses. Observed queen problems during the season increased the probability of losing colonies to unsolvable queen problems. A notable number of bees with crippled wings during the foraging season resulted in high losses and could serve as an alarm signal for beekeepers. Migratory beekeepers and large operations had lower loss rates than smaller ones. Additionally, we investigated the impact of several hive managemen<sup>t</sup> practices. Most of them had no significant effect on winter mortality, but purchasing wax from outside the own operation was associated with higher loss rates. Colonies that reported foraging on maize and late catch crop fields or collecting melezitose exhibited higher loss rates. The most common *Varroa destructor* control methods were a combination of long-term formic acid treatment in summer and oxalic acid trickling in winter. Biotechnical methods in summer had a favourable effect on colony survival.

**Keywords:** *Apis mellifera*; varroa control; colony losses; forage; beekeeping; citizen science; overwintering; monitoring
