J Scott Shannon (![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png)
otterfamily) wrote2007-12-05 01:16 pm
otterfamily) wrote2007-12-05 01:16 pm
Entry tags:
Grist for Nature's mill
My study was originally about the behavioral development of young otters, so the focus of my attention was mostly on the pups. There's hardly anything cuter than a baby otter, and watching them grow up was the joy of my life back then. However, it also brought me the most sorrow.
You see, from 1983-2006, I studied 58 otter pups from 29 litters, and no fewer than 35 died within their first 10 months of life: a 60% infant mortality rate. A young otter's first year of independence was also a deadly period: counting that second year of life, 43/58 (73%) were dead before reaching sexual maturity at age 2. So during that 23-year period, only 15 (1 out of 4) of the young I studied survived to adulthood - 6 females, and 9 males.
What kills so many young otters? In the first few weeks, it was mostly falls down the cliffs where the females had their nursery dens. Later on, crushing injuries caused by the dock platforms and ramps took a regular toll. Many young otters were killed by human cruelty, being intentionally hooked by people fishing at the pier.
All of these deaths were tragic to me, but nothing prepared me for the infanticides. Around 20% of the otter babies born here over the years were either abandoned to die by their mother, or were intentionally slain by elder female relatives. These internecine killings had devastating consequences. In fact, it was the murder of one yearling female by her elder sister in 1992 that set in motion the chain of events that resulted in all 3 adult females here dying within a fortnight, and continuing episodes of infanticide through succeeding years ultimately caused the extinction of the entire matrilineage.
Before the infanticides started, reproduction was sufficient to compensate for the man-caused mortalities, but after the otters started killing their own young, the population crashed, and it never recovered. Of Old Mama's 54 descendants born over a period of 23 years, only one, Slick, remains alive today.
So can you perhaps understand why this story is such a difficult one to tell? So much death, so much tragedy, and I'll say it... so much evil. Do you think the world really wants to know that otters are capable of such unspeakable acts?
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Here's a PDF file listing all of the pups I've studied and some statistics on their survival and mortality: download link.
You see, from 1983-2006, I studied 58 otter pups from 29 litters, and no fewer than 35 died within their first 10 months of life: a 60% infant mortality rate. A young otter's first year of independence was also a deadly period: counting that second year of life, 43/58 (73%) were dead before reaching sexual maturity at age 2. So during that 23-year period, only 15 (1 out of 4) of the young I studied survived to adulthood - 6 females, and 9 males.
What kills so many young otters? In the first few weeks, it was mostly falls down the cliffs where the females had their nursery dens. Later on, crushing injuries caused by the dock platforms and ramps took a regular toll. Many young otters were killed by human cruelty, being intentionally hooked by people fishing at the pier.
All of these deaths were tragic to me, but nothing prepared me for the infanticides. Around 20% of the otter babies born here over the years were either abandoned to die by their mother, or were intentionally slain by elder female relatives. These internecine killings had devastating consequences. In fact, it was the murder of one yearling female by her elder sister in 1992 that set in motion the chain of events that resulted in all 3 adult females here dying within a fortnight, and continuing episodes of infanticide through succeeding years ultimately caused the extinction of the entire matrilineage.
Before the infanticides started, reproduction was sufficient to compensate for the man-caused mortalities, but after the otters started killing their own young, the population crashed, and it never recovered. Of Old Mama's 54 descendants born over a period of 23 years, only one, Slick, remains alive today.
So can you perhaps understand why this story is such a difficult one to tell? So much death, so much tragedy, and I'll say it... so much evil. Do you think the world really wants to know that otters are capable of such unspeakable acts?
----------
Here's a PDF file listing all of the pups I've studied and some statistics on their survival and mortality: download link.