This is a chapter from my book, “Condor Tales: What I Learned in Twelve Years with the Big Birds (Symbios 2016), covering the beginnings of our fight to begin a condor captive propagation program.
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From my journal, Thursday 28 February 1974 - “Another wheel-spinning day, trying to determine changes in condor productivity and the size of the breeding population since Koford’s time - data are so scanty and hard to compare, it is a real frustration. I end up with feelings, but no facts. I don’t know how I’m going to justify a trapping and marking program without first trapping and marking to accumulate data to prove my feelings!!”
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In the months before Dean Carrier transferred to Idaho - the same time period when we were putting the finishing touches on the Recovery Plan that supposedly had the key to saving the species - the two of us spent hours at a time, going over and over the condor data, trying to see some hopeful signs. With Dean gone but the record still in front of me, I grew more and more frustrated. I built every life table I could think to build. I made every assumption I could think of about the condor population, some very optimistic and some very pessimistic. No matter how I juggled the data - or my thinking - I came up with the same answer: the condors were in deep trouble. Finally, I couldn’t stand it, anymore. I put together what I called a “discussion document,” titled it Contingency Planning for the California Condor, and on 8 January 1974 - just a little more than a year before the Condor Recovery Plan was approved - sent it off to all the Recovery Team members. I’ve reproduced quite a bit of that report below, because it helped shape much of my activity in the following years, and was the justification on which we eventually built much of our proposal for capturing condors.
“I believe that continued low recruitment in the California condor population, despite considerable protection and management in recent years, is cause for immediate concern. It appears more and more likely that the population is in very serious trouble, and that we are at the point at which we must consider management alternatives that some critics will label drastic, undesirable and unnecessary, and that may cause us considerable ‘political’ and public relations problems.
“I am not suggesting discarding or revising our Condor Recovery Plan. Implementation of the Plan items is a requirement if we are to give the condors their best chance for survival. However, the Recovery Plan may prove inadequate by itself, and the population appears to be reaching such a vulnerable point that it may be necessary to enact emergency plans on very short notice.
“We believe the condor population numbers somewhere between 50 and 60 birds, and that effective reproductive life does not start for some time after birds acquire their ‘adult’ plumage. Assuming a total population of 55 birds and a minimum breeding age of 8 years, there are in the present population 41 adults (31 in the Sespe-Sierra, 10 in the Coast Ranges) and 14 sub-adults (9 in the Sespe-Sierra, 5 in the Coast Ranges). Probable uneven sex ratios and spatial separation lowers pairing possibilities somewhat, so I estimate the total possible pairs as 12 in the Sespe-Sierra and 3-4 in the Coast Ranges. As they nest only once every two years, there could be 6 nests per year in the Sespe-Sierra and 2 nests per year in the Coast Ranges. Assuming some nest failure, we could get 3-5 successful nests per year in the Sespe-Sierra, and 1-2 successes in the Coast Ranges.
“If average annual mortality is between 5 and 10 per cent (Koford’s estimate, and it still seems reasonable), then 3 to 6 young would be needed each year for the population to remain stable. So, with what appears to be current maximum reproductive capability, the population can just barely remain stable.
“Actually, for so far incompletely understood reasons, current annual productivity appears to average only about 2 young, much less than is needed to keep the population stable. Therefore, (1) annual mortality must be less than 5 per cent (highly unlikely in any wild population, and certainly not sustainable over any long period of time), (2) we’re underestimating annual productivity (possible, but there would be field evidence if it was much higher), or (3) the population is declining even now. The latter seems more and more likely to me.
“Again assuming a population of about 55 birds, and also assuming (apparently pretty validly) (1) an average annual productivity prior to 1968 approximately double the current rate, and (2) evenly distributed mortality among adult birds, it is unlikely that many condors are living beyond 25 years of age. The relatively stable population size despite continuing low productivity means a large proportion of the population must be potentially to the point at which ‘old age’ deaths could increase markedly, with a resulting major decrease in population size and productivity. To show how serious - and how immediate - the decline could be, I’ve calculated the following from very rough (but I believe reasonably representative) life table data:
1973 - about 49 birds under 20 years old (14 subadult)
1978 - at current production and mortality rates, only
about 43 birds under age 20 (14 subadult)
1983 - only 31 birds under age 20 (14 subadult)
“These figures are estimates, but I believe they validly illustrate two ideas:
“(1) Within 10 years, only about 60 per cent of the present 55-bird population will be under 20 years of age, which means a large share of the other 40 per cent could already be dead or approaching death. In other words, within 10 years a major decline in total numbers could occur.
“(2) Assuming no change in average length of reproductive life within the next 10 years, the potential breeding population could be reduced by as much as 50 per cent in that time. Because the population already appears to be functioning well below its apparent reproductive potential, the actual effect on annual productivity could be that no production might be expected in some years. This would be disastrous to the population.”
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The imprecision of my case - the blatant speculations - would have made any red-blooded statistician scream in mental pain. But after all the years of studying the condor from afar, it was the best anybody could have done. Put all of Koford’s, Sibley’s, Carrier’s and my studies together, and there was still nothing any statistician could do to help me out. I wanted to correct that failing, and to maybe reverse the condor populations’ downward trend.
“My figures may be overly pessimistic, but I believe there is little question the condor situation is deteriorating rapidly. My suggestions for future action are as follows:
“(1) Implement all items in the Condor Recovery Plan as rapidly as possible, especially those directly related to increasing production and decreasing mortality. The supplemental feeding program must get into high gear immediately.
“(2) Immediately intensify and refine population inventory techniques and productivity estimates, to check the validity of our population parameter estimates, and to monitor trends. I don’t believe this can be done without capturing, marking and releasing some condors, so we can identify positively at least some of the birds in the population individually. It may be tough to get approval for this, and may get us some bad publicity, but consider the facts and benefits.”
Here I described the relative ease and safety with which Andean condors had been captured on a number of occasions, and gave some ideas of what I had already learned about possible identification markers we could place on captured birds. I listed fifteen different types of information that might be obtained through a capture and release program, that we had not been able to obtain without being able to identify individual birds. These included: improving the accuracy of our population size and productivity estimates (knowing how many times per count we were seeing the same birds over and over again would revolutionize our “educated guesses” at the end of surveys); determining how far breeding pairs were traveling in search of food; proving or disproving my hypothesis that condors lived in subpopulations that did not usually intermix; determining the age of first breeding; and measuring longevity. Some of this information would be of immediate value and use; some would be important if the condor population survived.
My final recommendations were:
“(3) Continue to search for ways to enhance the status of the population in the wild.
“(4) Take into captivity 6 to 8 condors, and attempt a captive rearing and release program if any of the following conditions occur: (a). If by 1978, annual productivity has not risen above 2 young per year; (b). If, between now and 1978, annual productivity falls below 2 young per year for 3 years straight; or (c). If at any time there appear to be no more than 40 birds in the total population.”
“Under any of the above circumstances, it would be highly unlikely that the condor population could continue to sustain itself. Therefore, captive propagation would have to be considered truly a ‘last ditch’ attempt to save the birds.”
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After some discussion of a captive breeding program, I gave a final admonition: “I know we are all, individuals and agencies, a little ‘gun shy’ about talking about trapping and propagating endangered species. However, I think we’re talking more and more about a life and death issue with the condor. If we’re really concerned about saving it, I think we have to be prepared to collectively take some flak and stir up some controversy. Whatever we decide to do, I think we should not kid ourselves or the public into thinking that the condor problem is taken care of, or that we can take care of it with more of the ‘leave them alone’ techniques that we have been forced to practice in the past. Now is the time for your very open and candid consideration of these issues.”
I don’t think I expected much from my impassioned plea. Therefore, the Recovery Team meeting of 18 January 1974 came as a real surprise. From my journal: “Contingency planning - Team members had already seen my memo suggesting that the condor might be past saving within as few as 10 years. There was considerable discussion of a trapping and marking program (needs, methods, safety to birds, public relations problems), then unanimous agreement that we should go ahead. We discussed future propagation - I made it clear I was still not ‘for it’ but that it looked like we better be realistic now and begin paving the way in case it was needed later. There was also general concurrence in this, although the Team did not adopt my timetable as such.”
We were on our way.
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