Seasonal changes in food selection and nutrition of captive platypuses (Ornithorhynchus anatinus)

Abstract

Anecdotal observations of captive platypuses (Ornithorhynchus anatinus) suggest that they show a seasonal preference for particular foods, but this has never been rigorously measured. This study aimed to determine seasonal food preferences and energy consumption of captive platypuses so that better protocols for maintaining platypuses in captivity can be developed. Seven platypuses were fed an ad libitum diet with all food items weighed in and out of tanks. Food items were analysed for energy, fats, carbohydrates, proteins, vitamins and minerals. Platypuses preferred less mobile prey (mealworms, earthworms and fly pupae) over highly mobile prey (crayfish). There was no significant seasonal change in preference for different dietary items, which is more likely to be driven by prey behaviour. Crayfish contributed the largest percentage (mass) consumed and was highly nutritious. While the relative percentage of items in the diet did not change seasonally, the quantity eaten did. The mean energy intake of platypuses was 921 kJ kg–1 day–1 and varied seasonally, being lowest during the breeding season (810 kJ kg–1 day–1) and highest in the postbreeding season (1007 kJ kg–1 day–1). These changes were associated with preparation and recovery from the breeding season. We conclude that the platypus diet is influenced by nutrition and seasonal factors as well as by prey behaviour. This knowledge will contribute to improving the husbandry and management of platypuses, which are widely recognised as difficult to maintain in captivity.

The platypus: evolutionary history, biology, and an uncertain future

“…Research into platypus diets is mostly based on sampling the contents of cheek pouches (Grant and Carrick 1978; Faragher et al 1979; McLachlan-Troup et al 2010; Marchant and Grant 2015) or analysis of captive nutrition (Thomas et al 2018b), with more recent application of stable isotope analysis of platypus fur indicating that a combination of cheek pouch and stable isotope analyses is the most thorough approach (Klamt et al 2016). Feeding behavior of captive platypuses indicates that preferences are shaped by prey mobility and increased energy consumption associated with preparing for and recovering from breeding (Thomas et al 2018b). Body condition can be measured using tail volume and fur condition (Grant and Carrick 1978), but portable ultrasound devices offer new and potentially more accurate indices of body condition (Macgregor et al 2017a).…”

“…Platypuses also feed on freshwater crayfish (normally genus Cherax ) in captivity and on members of this and other genera in the wild, although this is less common (Krueger et al 1992; Bethge 2002). Daily food consumption is 13–28% of body weight (non-breeding individuals—Krueger et al 1992; Munks et al 2000; Bethge et al 2001; Thomas et al 2018b), but is much higher (90–100%) in lactating females (Holland and Jackson 2002), suggesting increased energy expenditure. The platypus can exert top-down influence in aquatic environments, but to a variable extent (McLachlan-Troup 2007).…”

Marsupial and monotreme milk—a review of its nutrient and immune properties

“…Platypus will consume up to 2,093 kJ kg −1 d −1 during lactation which is 227% that of non-lactating females (Thomas et al, 2020). Like marsupials, there seems to be minimal increases in energetic needs of female platypus in the first month of lactation (Thomas et al, 2017;Thomas et al, 2020). More data is needed on maternal nutrition from a wider range of marsupials and monotremes to understand how nutrient demands change throughout lactation.…”

Peer Review #1 of "Marsupial and monotreme milk—a review of its nutrient and immune properties (v0.1)"

“…Platypus will consume up to kJ kg -1 d -1during lactation which is 227% that of non-lactating females (Thomas et al 2020). Like marsupials, there seems to be minimal increases in energetic needs of female platypus in the first month of lactation (Thomas et al 2017;Thomas et al 2020). More data is needed on maternal nutrition from a wider range of marsupials and monotremes to understand how nutrient demands change throughout lactation.…”