Time Budgets in Domesticated Male Icelandic Horses on Pasture Turnout in Winter and Spring

TL;DR

This study tracks the daily activities of Icelandic horses in winter and spring, finding they spend more time foraging and moving in spring, and less time standing.

Contribution

The study provides a rare 24-hour continuous time budget for domesticated horses at pasture, comparing seasonal behavioral patterns.

Findings

Horses foraged longer and stood less in spring compared to winter.

All horses lost body condition in winter but regained it in spring.

Grazing time exceeded recommended minimums for stabled horses in both seasons.

Abstract

Recording the behaviour of horses over 24 h is time-consuming and can be difficult during hours of darkness. A behavioural time budget is normally compiled by sampling the behaviour of individuals at specific intervals (e.g., every 5–10 min), but this can risk missing certain behaviours. In this study, a 24 h time budget of continuous behaviour over 3 h periods was conducted in winter and spring during fair weather to examine seasonal variation for a mixed-age herd of eight male domesticated Icelandic horses (seven geldings, 1 stallion). Individual behaviour and herd location were continuously observed during 3 h periods to cover 3 days (72 h) in both seasons. In spring, horses spent longer foraging, moving, and lying down, but spent less time standing compared to winter. There was little behavioural difference between adult and young horses. All horses lost body condition over winter and regained it over spring. The herd showed preferences for certain areas of the field for specific behaviours and during certain weather conditions. Grazing time (12–17 h) over 24 h in both seasons exceeded recommended minimum foraging times of 8–10 h for stabled horses to meet their behavioural needs, and fasting periods of the herd rarely exceeded 2 h.

There are few 24 h time budgets for horses, especially for domesticated horses kept at pasture. Most time budgets utilise short-term scan sampling, which can miss behaviours. This study aimed to assess the seasonal variation in continuous behaviour of domesticated Icelandic horses at pasture during winter and spring in fair weather. Eight Icelandic horses (11.25 ± 9.19 years; 7 geldings, 1 stallion) were observed in a 26 acre field. Herd location and individual behaviour were continuously observed during 3 h periods amounting to 3 × 24 h in winter and late spring, compiled over 43 days (~21 days per season). Seasonal variation in behaviour (ANOVA), body condition (RMANOVA), and age-group variation (independent t-test) were assessed, as well as associations between weather, time period, and habitat choice (chi-square). During spring, horses showed more foraging (+18%; p < 0.001), movement (+0.5%; p < 0.05), recumbency (+5.7%; p < 0.01) and less standing (−24.6%; p < 0.001) than in winter. Behavioural synchronicity occurred between adult and juvenile horses. Mean body condition reduced from 5.6 to 4.8 in the winter. Habitat preferences varied by daytime and season, and non-feeding periods lasted less than 2 h. The 24 h foraging activity (winter: 12.7 ± 0.4 h, spring: 17 ± 0.25 h) supported the current recommendation of 12 h/24 h for domesticated horses to meet ethological requirements.

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