Eurasian Lynx (Lynx lynx)
- The basal metabolism rate (BMR) in animals is not a measure of daily energy expenditure, but rather a measure of the rate of metabolism during a resting, post-absorptive, thermal neutral and stress free state (McNab, 1988). The quantitative value of BMR in bobcats (Lynx rufus) was found to be 455.87kcal/day for an 8.64kg bobcat (Munoz-Garcia and Williams, 2005). The assumed BMR for the Eurasian lynx would be higher than the BMR for the bobcat. This is because the Eurasian lynx is larger in size and weight, which will increase the metabolic rate due to an increase in visceral size, which consumes a significant amount of energy to function (Burrin et al., 1990). Maintenance energy can be estimated at twice the BMR, so the maintenance energy required for the bobcat is approximately 911.74kcal/day (Kirkwood, 1991). Maintenance energy for the Eurasian lynx is assumed to be higher than requirements for the bobcat, for the same reasons as mentioned above.
- The daily energy expenditure (DEE) for Iberian lynx (Lynx pardinus) was found to be 912kcal/day for a 15.4kg lynx (Aldama et al., 1991). Since 15.4kg is within the typical weight range of the Eurasian lynx (15-29kg), and the Iberian lynx and Eurasian lynx share very similar daily activities, 912kcal is a reasonable assumption of DEE for a small Eurasian lynx.
- The energy required for pregnant female bobcats can range from 1230.85-1413.2kcal/day, while the energy required for lactating females can range from 1823.5-3191.1kcal/day. The assumed energy required for pregnant/lactating female Eurasian lynx would be higher due to a higher BMR in Eurasian lynx. Other factors such as; number of young, gestation length and cub independence are very similar in both species and would require approximately the same energy. Reproductive success in the Eurasian lynx is positively correlated with the amount of energy consumed and used for reproduction (Bunnefeld et al., 2006).
(Eurasian Lynx with 5 month old cubs, Eric Baccega, www.arkive.org)
- The growth requirement for any animal encompasses an increase in calories consumed to increase protein and fat deposition while decrease body water content (Robbins, 1983). The energy requirement was found to be 140kcal/kg for a domestic cat with a weight of 4.5kg (Ahlstrom et al., 2013). The energy requirement for growth of the Eurasian lynx is assumed to be higher since the Eurasian lynx grows to a higher average weight (22kg). Body size in mammals depends mainly upon the availability of prey during the growth period (Yom-Tov et al., 2011). Size is also positively correlated with energy intake, the larger Eurasian lynx are a result of increased prey consumption which results in a higher energy requirement (Yom-Tov et al., 2011).
A roe deer (size 23kg) would provide 1854.1kcal of energy (Weiner, 1973). If DEE = 912kcal/day, the Eurasian lynx would not even need to consume a whole roe deer in one day to meet requirements.
A domestic sheep (size 30kg) would provide 1952.68kcal of energy (Wilkinson, 2011). If DEE = 912kcal/day, then the Eurasian lynx would not even need to consume a whole sheep in one day to meet requirements.
A domestic sheep (size 30kg) would provide 1952.68kcal of energy (Wilkinson, 2011). If DEE = 912kcal/day, then the Eurasian lynx would not even need to consume a whole sheep in one day to meet requirements.
Eurasian Otter (Lutra lutra)
- The basal metabolism rate (BMR) in animals is not a measure of daily energy expenditure, but rather a measure of the rate of metabolism during a resting, post-absorptive, thermal neutral and stress free state (McNab, 1988). The quantitative value of BMR in Eurasian otters (Lutra lutra) was found to be 0.45 cm3 O2/g x h or 518.4kcal/day for a 10kg otter (McNab, 1988). The Eurasian otter had a higher BMR value compared to other mustelids who were close in size, such as the European badger and American badger (McNab, 1988). The high BMR can be attributed to their semi-aquatic nature and their high surface: volume ratio, this results in faster heat loss and a greater need to eat more food to maintain body functions (McGrosky, 2016). Maintenance energy can be estimated at twice the BMR, so the maintenance energy required for the Eurasian otter is approximately 1036.8kcal/day (Kirkwood, 1991).
- The actual daily energy expenditure (DEE) for weasels (Mustela nivalis) was found to be 106kcal/day for a 0.134kg weasel (Moors, 1980). Since the average weight of an Eurasian otter is 8.55kg, the assumed expected DEE of an Eurasian otter is much higher than 106kcal/day. The DEE is also assumed to be much higher due to the Eurasian otters’ aquatic activity which results in large metabolic costs to maintain body temperature (Kruuk, 1997). DEE for eutherian mammals can be estimated as 2.3 x BMR. 2.3 x 518.4kcal = 1192.32kcal/day.
- Eurasian otters have adapted their breeding times to match the maximal abundance of fish, so that they can get enough energy from food to support the growth of their cubs (Ruiz-Olmo and Jimenez, 2009). The energy required for pregnant Eurasian otter females can range from 1399.68-1607.04kcal/day, while the energy required for lactating females can range from 2073.6-3628.8kcal/day. Ruiz-Olmo and Jimenez (2009) also found that there was an increase in the frequency of breeding of Eurasian otters in more stable and complex environments.
(Common otter adult with cubs, Dave Kilbey, www.arkive.org)
- The growth requirement for any animal encompasses an increase in calories consumed to increase protein and fat deposition while decrease body water content (Robbins, 1983). The energy requirement for growth of a mink (Mustela vison) was found to be 2.966kcal/g for a 750g mink (Robbins, 1983). The energy requirement for growth of the Eurasian otter is assumed to be higher since the Eurasian otter grows to a higher average weight (8.55kg). It was also found that females had a slower growth rate compared to male Eurasian otters, which correlates with lower growth requirements in females (Heggberget and Moseid, 1994).
A cod (size 500g) would provide 70.7kcal x 5 = 353.5kcal of energy (Usydus et al., 2011). if DEE = 1192.32kcal/day then the Eurasian otter would need to consume 4 cod, each weighing around 500g per day.
A frog (size 22.7g) would provide 86.7kcal of energy (Tokur et al., 2008). If DEE = 1192.32kcal/day, then the Eurasian otter would need to consume 14 frogs, each weighing around 22.7g per day.
A frog (size 22.7g) would provide 86.7kcal of energy (Tokur et al., 2008). If DEE = 1192.32kcal/day, then the Eurasian otter would need to consume 14 frogs, each weighing around 22.7g per day.