I will jump into the fray here with more thoughts on the Rufous-collared Sparrow and vagrancy (if you are already sick of this debate, I strongly recommend hitting the delete key now):
1. First, many of us are passionate about birding, so we can expect many discussants to have strong opinions. Let’s keep the conversation civil. I say this, not because the conversation has strayed from civility, but because I sense a strong potential for egos to be challenged. We’ll be fine if we remember that no one knows everything, and all opinions are welcome, and even the experts make mistakes. Let’s use this conversation as an opportunity to increase knowledge among the entire COBirds community. 2. We don’t have to reinvent the wheel. This is not the first time an odd bird has been discovered, and the bird authorities have had to consider whether it should or should not be added to the official State List. Some states (all states? Colorado?) use the category of “Hypothetical” to indicate that a report of occurrence exists, but that there is not sufficient evidence to conclude that it should be considered part of a state’s natural avifauna. Often the hypothetical list is annotated to describe the circumstances of the report. 3. Examples of hypothetical reports include: 1. single observer reports of potential first state records with no credible witnesses, 2. specimen records for which the specimen cannot be located, 3. specimen records with suspected labeling errors, 4. specimen records (or other documentation such as photo, video or audio) in which the authenticity of the documentation is suspect, 5. documented observations for which captive or native provenance is uncertain, 6. local populations of introduced species which may not be sufficiently established. By using the Hypothetical category as an addendum to the list, all of these reports would be added to the list, but with an asterisk. See item #8 below for a list of species that probably should be on Colorado’s hypothetical list. 4. The mission of the CBRC is to judge, based on available evidence, whether an occurrence of a bird should be added to the official record. All reported occurrences, whether receiving an “accept” vote or a “reject” vote, gets archived for future potential reconsideration. For the case of a new state record, the CBRC rightly acts with caution before voting to “accept” the record. Seven members vote; the results of the vote (number of votes for and against) are published for all to see in the CBRC Reports which are published in Colorado Birds. To err on the side of caution, an “accept” decision requires one or less dissenting vote, by statute. To be fair, prior to rejecting a record with more than one dissenting vote, a second round of debate ensues and often expert opinion is consulted from outside the Committee. Submitters of reports should not view the Committee’s decisions as a judgment of an observer’s abilities. I have had many submissions rejected. If I were on the Committee I would have voted to accept all of them. Clearly, at least 2 voters disagreed (or were more conservative than me). That is a fair process. I cannot think of a better system, except perhaps to have committee members ratified by a vote of the CFO membership, which would truly make it democratic, at least within CFO. 5. The CBRC is not the arbiter of what birds may be added to one’s list. The list owner is. If the list owner decides to only count rare birds that are “accepted” by the CBRC, that is their prerogative, but there is no listing rule that requires this. Of course, the more conservative one is, the more likely one’s list will be believed by others. However, being too conservative is not good for science either, because real occurrences of unusual birds may be discounted purely due to low probability of occurrence. Dogma is never good for science. 6. Examples of scientific dogma throughout history are: 1. the Earth is flat, 2. species were originally created in their current form, and 3. a Rufous-collared Sparrow cannot reach Georgetown CO without human assistance. The first two have been proven wrong. The third is still a matter of debate. 7. The whole issue of the null hypothesis does not sit well with me with respect to this sparrow. First, the null hypothesis arises from an hypothesis. The hypothesis arises from a question. The question in the case of the Georgetown bird is “Could this bird be a wild vagrant?” If the bird was a Budgerigar, no-one would question that it was likely an escaped cage-bird, because our common experience tells us that such occurrences are not very rare, but a vagrant from Australia (or even from the small established population of budgies in Florida) would be very rare. So the hypothesis would be that the budgie is a wild vagrant. The null hypothesis is that the budgie is NOT a wild vagrant, but rather the only other alternative, an escaped captive bird. To test this, we might consider which is a more likely event. Since budgies escape frequently in Colorado, but a vagrant budgie has never been suspected in North America, we cannot reject the null hypothesis with any certainty. Now, how many caged Rufous-collared Sparrows have you seen in Colorado? I’ll bet the answer (collectively, among all who read this) is zero vs thousands of budgies and lovebirds. So, even an escaped Rufous-collared Sparrow would be an extremely rare event, especially considering that the bird does not look or act like a captive bird. So, what is the hypothesis in the case of the Georgetown bird? The hypothesis is that the sparrow is a wild vagrant. Therefore, the null hypothesis is that it is NOT a wild vagrant, but rather the more likely alternative, which is.......what? Since an escaped sparrow has never occurred, it is not more likely. Since an airplane-assisted sparrow has never occurred, it is not more likely. I think a different approach is needed here. How about a retrospective study to determine where the bird was when it last molted its feathers, using geographically specific radioisotope concentrations. Or a prospective study, tracking its future movements by marking it with a leg band (or even better, a satellite radiotransmitter). Each of these strategies would be technically challenging and would have a low probability of success, but it would be a probability greater than zero, which is where we are now. 8. If I were on the CBRC, I would vote for the sparrow to be added to the Hypothetical list. Here are some other birds that should be on the Hypothetical list: The Yellow Grosbeak in Albuquerque (New Mexico), White-throated Magpie-Jay (Arizona), both occurrences similar to the Georgetown sparrow; perhaps the Streak-backed Oriole in Loveland; Mute Swans and Mandarin Ducks (are these local breeders established in Colorado?). How about California Quail in Colorado – have any of the northwest Colorado observations been submitted to the CBRC? Perhaps the Cactus Wren reported last year in southeastern Colorado (assuming the documentation submitted described a Cactus Wren). 9. My favorite hypothesis so far: Keith Alderman’s theory that the sparrow hitched a ride with circus lions rescued from Bolivia. According to the article that Keith cited, the Lions were transferred to a large indoor facility northeast of the airport in Keenesburg, CO. Maybe there are people associated with the rescue that could comment on whether a bird had climbed on board in La Paz, or flown out of the plane upon arrival in Denver, or even accompanied the lions to Keenesburg. Maybe there were other Bolivian birds (Rufous-collared Sparrows or otherwise) that are still with the lions. The story of the lions is just as fascinating as the untold story of the sparrow. Nick Komar Fort Collins CO -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to cobirds@googlegroups.com. To unsubscribe from this group, send email to cobirds+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/cobirds?hl=en.
