Archive for grizzly bear

Measuring abundance [book review]

Posted in Books, Statistics with tags , , , , , , , , , , , , on January 27, 2022 by xi'an

This 2020 book, Measuring Abundance:  Methods for the Estimation of Population Size and Species Richness was written by Graham Upton, retired professor of applied statistics, for the Data in the Wild series published by Pelagic Publishing, a publishing company based in Exeter.

“Measuring the abundance of individuals and the diversity of species are core components of most ecological research projects and conservation monitoring. This book brings together in one place, for the first time, the methods used to estimate the abundance of individuals in nature.”

Its purpose is to provide a collection of statistical methods for measuring animal abundance or lack thereof. There are four parts: a primer on statistical methods, going no further than maximum likelihood estimation and bootstrap. The term Bayesian only occurs once, in connection with the (a-Bayesian) BIC. (I first spotted a second entry, until I realised this was not a typo and the example truly was about Bawean warty pigs!) The second part is about stationary (or static) individuals, such as trees, and it mostly exposes different recognised ways of sampling, with a focus on minimising the surveyor’s effort. Examples include forestry sampling (with a chainsaw method!) and underwater sampling. There is very little statistics involved in this part apart from the rare appearance of a MLE with an asymptotic confidence interval. There is also very little about misspecified models, except for the occasional warning that the estimates may prove completely wrong. The third part is about mobile individuals, with capture-recapture methods receiving the lion’s share (!). No lion was actually involved in the studies used as examples (but there were grizzly bears from Yellowstone and Banff National Parks). Given the huge variety of capture-recapture models, very little input is found within the book as the practical aspects are delegated to R software like the RMark and mra packages. Very little is written on using covariates or spatial features in such models, mostly dedicated to printed output from R packages with AIC as the sole standard for comparing models. I did not know of distance methods (Chapter 8), which are less invasive counting methods. They however seem to rely on a particular model of missing on individuals as the distance increases. The last section is about estimating the number of species. With again a model assumption that may prove wrong. With the inclusion of diversity measures,

The contents of the book are really down to earth and intended for field data gatherers. For instance, “drive slowly and steadily at 20 mph with headlights and hazard lights on ” (p.91) or “Before starting to record, allow fish time to acclimatize to the presence of divers” (p.91). It is unclear to me how useful the book would prove to be for general statisticians, apart from revealing the huge diversity of methods actually employed in the field. To either build upon these or expose students to their reassessment. More advanced books are McCrea and Morgan (2014), Buckland et al. (2016) and the most recent Seber and Schofield (2019).

[Disclaimer about potential self-plagiarism: this post or an edited version will eventually appear in my Book Review section in CHANCE.]

399 safe[[r] for now]

Posted in Kids, Mountains, pictures, Travel with tags , , , , , , , , , , , on October 14, 2018 by xi'an

and it only gets worse…

Posted in Kids, pictures with tags , , , , , , , , , , , , , , , , , , , , , , , on July 23, 2018 by xi'an

“David Brooks, the New York Times columnist, recently summed up the “Trumpian world-view” writing, “Trump takes every relationship that has historically been based on affection, loyalty, trust and reciprocity and turned it into a relationship based on competition, self-interest, suspicion and efforts to establish dominance.” NYT, June 14

“Donald Trump has dismissed concerns about the widely condemned human rights record of the North Korean dictator, Kim Jong-un, praising him as a “tough guy”, a “smart guy” and a “great negotiator”.” The Guardian, June 14

“Clinics that call themselves crisis pregnancy centers are not obliged to tell women when state aid may be available to obtain an abortion, according to a US supreme court ruling that represents a blow to pro-choice groups (…) All three of the court’s female members dissented.” The Guardian, June 27

“A resolution to encourage breast-feeding was expected to be approved quickly and easily by the (…) United Nations-affiliated World Health Assembly. Based on decades of research, the resolution says that mother’s milk is healthiest for children and countries should strive to limit the inaccurate or misleading marketing of breast milk substitutes. Then the United States delegation, embracing the interests of infant formula manufacturers, upended the deliberations. The intensity of the administration’s opposition to the breast-feeding resolution stunned public health officials and foreign diplomats, who described it as a marked contrast to the Obama administration.” NYT, July 8

“President Trump on Tuesday pardoned a pair of Oregon cattle ranchers who had been serving out sentences for arson on federal land (…) The pardons undo an Obama administration appeal to impose longer sentences for the Hammonds and show that, at least in this case, the Trump administration is siding with ranchers in the battle over federal lands.” NYT, July 10

“President Trump stood next to President Vladimir V. Putin of Russia on Monday and publicly challenged the conclusion of his own intelligence (…) “No prior president has ever abased himself more abjectly before a tyrant,” Senator John McCain, Republican of Arizona, said in a statement. “Today’s press conference in Helsinki was one of the most disgraceful performances by an American president in memory.” ” NYT, July 16

“The Interior Department on Thursday proposed the most sweeping set of changes in decades to the Endangered Species Act, the law that brought the bald eagle and the Yellowstone grizzly bear back from the edge of extinction but which Republicans say is cumbersome and restricts economic development.” NYT, July 20

a ghastly ghost

Posted in Books, Kids, Mountains with tags , , , , , , , , , , , , , , , , , , , , on March 13, 2016 by xi'an

My daughter sort of dragged me to watch The Revenant as it just came out in French cinemas and I reluctantly agreed as I had read about magnificent winter and mountain sceneries, shot in an unusually wide format with real light. And indeed the landscape and background of the entire movie are magnificent, mostly shot in the Canadian Rockies, around Kananaskis and Canmore, which is on the way to Banff. (Plus a bit in Squamish rain forest.) The story is however quite a disappointment as it piles up one suspension of disbelief after another. This is a tale of survival (as I presume everyone knows!) but so implausible as to cancel any appreciation of the film. It may be the director Iñárritu is more interested in a sort of new age symbolism than realism, since there are many oniric passages with floating characters and falling meteors, desecrated churches and pyramids of bones, while the soundtrack often brings in surreal sounds, but the impossible survival of Hugh Glass made me focus more and more on the scenery… While the true Hugh Glass did manage to survive on his own, fixing his broken leg, scrawling to a river, and making a raft that brought him to a fort downstream, [warning, potential spoilers ahead!] the central character in the movie takes it to a fantasy level as he escapes hypothermia while swimming in freezing rapids, drowning while wearing a brand new bearskin, toxocariasis while eating raw liver,  bullets when fleeing from both Araka Indians and French (from France, Louisiana, or Québec???) trappers, a 30 meter fall from a cliff with not enough snow at the bottom to make a dent on, subzero temperatures while sleeping inside a horse carcass [and getting out of it next morning when it should be frozen solid], massive festering bone-deep wounds, and the deadly Midwestern winter… Not to mention the ability of make fire out of nothing in the worst possible weather conditions or to fire arrows killing men on the spot or to keep a never ending reserve of bullets. And while I am at it, the ability to understand others: I had trouble even with the French speaking characters, despite their rather modern French accent!

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