Diving behaviors of juvenile northern and southern elephant seals

Understanding the ontogeny of diving behavior in marine megafauna is crucial due to its influence on foraging success, energy budgets, and mortality. We compared the ontogeny of diving behavior in two closely related species – northern elephant seals (Mirounga angustirostris, n = 4) and southern elephant seals (Mirounga leonina, n = 9) – to shed light on the ecological and evolutionary processes underlying migration. Although both species have similar sizes and behaviors as adults, we discovered that juvenile northern elephant seals have superior diving development, reaching 260 meters diving depth in just 30 days, while southern elephant seals require 160 days. Similarly, northern elephant seals achieve dive durations of ~11 minutes on their first day of migration, while southern elephant seals take 125 days. The faster physiological maturation of northern elephant seals could be related to longer offspring dependency and post-weaning fast durations, allowing them to develop their endo..., Study System and Animal Handling
In 2018, 24 juvenile northern elephant seals (15 females and 9 males) from the population at Año Nuevo Reserve, CA, USA (Figure 1A; 37°5’ N, 122°16’ W) were equipped with an archival time-depth recorder (MK9, Wildlife Computers, measures time, depth, light) to record their very first trip to sea. The tags of only four individuals (4 females; mean weaning mass ± SD = 133 ± 10 kg; mean straight length from nose to tail tip ± SD = 139 ± 7 cm) were recovered when they returned to land after 229 ± 16 days at sea. Animals were sedated with an initial injection of tiletamine hydrochloride and zolazepam hydrochloride (Telazol), administered intramuscularly. Immobilization was maintained with intravenous injections of Ketamine when needed. Using quick-setting epoxy (Loctite®, Epoxy General Purpose), the MK9 tag was affixed to the fur on the center of the back.
In 2014, 20 juvenile southern elephant seals (10 females and 10 males) from Kerguelen Islands, sub-Antar..., , # Diving behavior of juvenile northern and southern elephant seals

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Understanding the ontogeny of diving behavior in marine megafauna is crucial due to its influence on foraging success, energy budgets, and mortality. We compared the ontogeny of diving behavior in two closely related species - northern elephant seals (*Mirounga angustirostris*, n = 4) and southern elephant seals (*Mirounga leonina*, n = 9) - to shed light on the ecological and evolutionary processes underlying migration. Although both species have similar sizes and behaviors as adults, we discovered that juvenile northern elephant seals have superior diving development, reaching 260 meters diving depth in just 30 days, while southern elephant seals require 160 days. Similarly, northern elephant seals achieve dive durations of ~11 minutes on their first day of migration, while southern elephant seals take 125 days. The faster physiological maturation of northern elephant seals could be related to longer offspring de...