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Longer nursing period reduces previous estimate of reproductive potential for northern bottlenose whales by ½ + provides evidence of prolonged maternal care in beaked whales. New OA pub out today with @ShuTingZhao1 and 2 non tweeters in @PLOSONE https://doi.org/10.1371/journal.pone.0235114
Our methods are fun: Using a rare collection of northern bottlenose whale teeth taken by whalers in the 1970’s, we used a small drill connected to a microscope to sample individual layers in each tooth and analyzed the #stableisotopes
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FUN FACT: The layers in teeth (GLGs) are like tree rings, they can be counted to estimate age and record a chemical signature of what each animal ate that year when they were alive ~50 years ago
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Milk has a higher 15N isotope signature than the prey (squid) of adult northern bottlenose whales, and drinking momma’s milk is reflected in your tissues with the signature of a higher trophic level
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Across 50 specimens of northern bottlenose we analysed, there was a slow decline in d15N that did not approach adult values until after age 3-4, indicating whales were still nursing.
6.The previous estimate of nursing duration for northern bottlenose whales (~ 1 year) was based on very limited data taken by whalers from the stomach contents of a calf (*N= 1).
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Take away 1: Because nursing and pregnancy rarely overlap in whales, prolonged maternal care implies #northernbottlenosewhales reproductive capacity may also be ~ 50% of previous estimates!
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Take away 2: Recovery of #northernbottlenosewhales from a century of whaling will be slower than we thought.... & any other sharp declines due to contemporary threats such as mass stranding events or disease will risk making things worse 8/N
Take away 3: Nursing duration, reproductive capacity and energetics of #beakedwhale species has often been extrapolated using limited data we had for northern bottlenose - QPQ prolonged maternal care may occur in other beaked whale species!
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While previous studies by @albirostris et al. did not find evidence of maternal social structure in northern bottlenose whales, there is clearly kin recognition beyond the first year of life… AKA we found MORE #beakedwhale questions! 10/N
