Do US crime statistics miss out the most violent cities?

Summary

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More or Less – "Do US crime statistics miss out the most violent cities?"

BBC Radio 4 | Host: Tim Harford | October 23, 2024

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Episode Overview

This episode of "More or Less" tackles several statistics at the heart of current public debate, scrutinizing and sometimes debunking claims that have gained traction in politics and media. The main focus is on whether US crime figures exclude America’s most violent cities—a claim made by Donald Trump and echoed by Elon Musk. The episode also covers British capital gains tax misunderstandings, the rationale behind the Bank of England's 2% inflation target, a statistic about GP suicide in the UK, and an investigation into the eating habits of grizzly bears.

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Key Discussion Points & Insights

1. Capital Gains Tax: Are Only 12,000 People Paying?

[00:45–06:20]

• Claim: Conservative MP Andrew Mitchell stated only ~12,000 people pay capital gains tax.
• Listener Response: Edward Letham questions this low figure, based on his own experience.
• Expert Insight:
  • Dr. Arun Advani (Centre for Analysis of Taxation, IFS):
    • The true number is "more like 350,000 to 400,000 in any given year. So last year it was about 370,000." ([02:21])
    • The 12,000 figure refers to a narrow group: "12,000 people pay something like two thirds of the tax." ([02:44])

Why raising rates doesn’t always raise revenue:

• Behavioral responses: People can defer selling assets or find ways to avoid higher tax.
• "If you increase the top rate of capital gains tax by 10 percentage points...they forecast that within a couple of years, you're actually losing £2 billion." ([03:15])

Suggestions for effective reform (Dr. Advani):

• Equalize capital gains and income tax rates, but provide an investment allowance
• Eliminate "death uplift" (where gains are erased at death)
• Tax gains before emigration (like in Canada/US/Australia)

Quote:

• “All of those things would raise another £14 billion. It's almost doubling the size of the tax at the moment.” ([06:03])

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2. US Crime Statistics: Are the Most Violent Cities Excluded?

[06:20–11:03]

• Claim: Trump suggests metrics are "fake," as the FBI "left out large numbers of areas where they had a lot of crime." ([07:58])
• Echoed by Elon Musk: Questioned missing homicide data in major cities.

Official Data:

• FBI compiles crime statistics submitted by ~18,000 local agencies. ([09:08])
• Coverage in 2023: 85% of agencies (94% of population).
  • All major cities—including New York, LA, Chicago, Detroit, and New Orleans—are included in the 2023 data. ([10:02]–[10:22])
  • The largest omitted city is Jacksonville, FL.

Expert (J. Albanese, Virginia Commonwealth U):

• “We have approximately 18,000 police departments… collecting crime data is a much bigger administrative task than it is in most places.” ([09:08])

Conclusion:

• The claim that "crime hotspots" are missing from FBI data is unfounded for the 2023 data.
• Missing agencies tend to be smaller; coverage is comparable to 2020 (Trump’s presidency).
• US homicide and violent crime have fallen since 2020 (homicides down 15–16%). ([06:51])

Quote:

• "The 10 cities with the highest crime rates in the US are all included in the FBI data.” ([10:22])

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3. GP Suicide Rates in the UK – Misquoted Statistics

[11:03–16:23]

• Claim: "One in four GPs knows another GP that has taken their own life." ([11:35])
• Based on a misreading of a 2022 survey:
  • The survey asked about "general practice workers" known to have taken their own life, not GPs specifically.
  • High uncertainty: "24% said 'I don't know' in answer to this question." – Prof. Annette Yechler ([12:57])

Key Problems:

• The group surveyed is broader than just GPs.
• The metric ("know of someone") is vulnerable to duplication—one death could be reported by many respondents. "[F]or any one person who took their life, there'd be multiple people here possibly saying, yes, I knew of somebody." ([13:32])

Actual suicide rates (ONS data 2011–2015, next analysis due 2025):

• Male doctors: suicide rate about a third lower than working-age men in general.
• Female doctors: similar rate to the general female working-age population.
• Construction trades' male suicide rate is 60% higher than the working-age male average.

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4. Why Does the Bank of England Target 2% Inflation?

[16:46–21:08]

• Listener asks: Why not aim for zero inflation?
• Tim Harford explains:
  • Deflation (negative inflation) is economically perilous—debt burdens grow, people delay spending, which triggers downturn.
  • "People are often very reluctant to accept a fall in the price of their labor that is a pay cut..."
  • Modest inflation allows for real pay cuts without nominal wage reductions, smoothing labor market adjustments.
  • An inflation buffer allows interest rates to be pushed negative in real terms, boosting the economy if needed.
  • Why not a higher target? High inflation brings instability ("If inflation is, say, 50%, that is a mess… nobody really knows what anything costs because money has lost its meaning." [around 18:00]), confusion, and economic cost.
  • The 2% figure is somewhat arbitrary; "once these targets have been set, they are very hard to shift."

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5. Bear Facts: How Many Buffalo Berries Does a Grizzly Eat?

[21:08–26:59]

• Claim: Grizzly bears eat up to 250,000 buffalo berries a day.
• Expert: Dr. Frank Van Manen, US Geological Survey.

Research cited:

• Based on a classic 1975 Yukon study, analysis of bear scat showed >20,000 berries per "scat" (defecation), with around 10 scats per day → ~200,000–250,000 berries daily during "hyperphagia" (autumn fattening). ([24:06], [24:47])
• Calorie-based calculation for a bear’s needs in hyperphagia yields nearly the same result: about 200,000 berries per day. ([25:27]–[26:39])

Quote:

• “For me, it kind of gave me the confidence to say that those estimates were probably pretty reasonable.” – Dr. Van Manen ([26:48])

Memorable moment:

• How biologists "counted the number of berries in bear scat. And you can imagine that's quite an endeavor." ([23:48])

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Notable Quotes & Memorable Moments

• Dr. Arun Advani ([02:21]):
  "It's more like 350,000 to 400,000 in any given year. So last year it was about 370,000."
• Tim Harford ([06:51]):
  "According to the figures collected by the FBI, crime is down since Donald Trump's last full year in the White House, 2020."
• J. Albanese ([09:08]):
  “In the US we have approximately 18,000 police departments, which is a rather shocking number…”
• Beth Ashmead Latham ([10:22]):
  “The 10 cities with the highest crime rates in the US are all included in the FBI data.”
• Prof. Annette Yechler ([12:57]):
  "For most questions, the rate of people saying I don't know or I prefer not to say...is only around 1%. So tiny."
• Dr. Frank Van Manen ([24:47]):
  "Those animals that were focused on feeding on buffalo berries were producing about 10 scats in a 24 hour time period. [...] Over 200,000 buffalo berries consumed in a 24 hour time period."
• Tim Harford ([18:00]):
  "If inflation is, say, 50%, that is a mess… nobody really knows what anything costs because money has lost its meaning."

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Timestamps for Key Segments

• Capital gains tax misunderstanding and expert correction: [00:45–06:20]
• US Crime statistics myth vs. reality: [06:20–11:03]
• GP suicide statistics challenged: [11:03–16:23]
• Why 2% inflation?: [16:46–21:08]
• Bear facts – Do grizzlies eat 250,000 berries a day?: [21:08–26:59]

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Conclusion

This episode demonstrates "More or Less" at its best—careful, nuanced, occasionally witty statistical sleuthing. By checking the facts behind headline-grabbing numbers, the team helps listeners understand not only the statistics themselves, but the assumptions, limits, and context behind them. This week's myth-busting includes a critical look at US crime data reporting, tax policy, and the feeding habits of North America’s great bears—with entertaining asides and clear explanations throughout.

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Transcript

[A]

BBC Sounds Music Radio Podcasts.

[B]

Hello, and welcome to More Or Less. We're your weekly guide to the numbers in the budget, the US election campaign and your local bear infested forest. And I'm Tim Harford. This week, was an MP wrong about the number of people who pay capital gains tax? Why does the bank of England try to ensure inflation is 2%? Why not zero? Donald Trump says US crime figures are fake. Are they? We fact check a claim about the prevalence of suicide among GPs and with the help of an expert, we comb through piles of bear excrement. And where on earth would you find that?

[C]

Well, the simple answer would be in the woods.

[B]

Let's start with capital gains. Earlier this month, the Conservative MP Andrew Mitchell was on Radio 4's Any Questions? And with the budget just a few weeks away, revenue raising taxes were a hot topic. One of the taxes under discussion was capital gains tax. This is a tax that's paid on the increase of a value of an asset when you sell it. Maybe a second home, maybe a company that you've built up as an entrepreneur and decided to sell. There are many rates for this tax, depending on your income and on the asset you're selling, but all of them are lower than the rates for income tax. And there's long been criticism of this disparity. But Andrew Mitchell didn't think that raising capital gains tax was a very good idea.

[D]

Only about 12,000 people pay capital gains tax, but these are huge entrepreneurs and business getters.

[C]

I think you've got to be very

[D]

careful that you don't destabilize the market and then get negative effects from. It's Alison McGovern.

[B]

Only 12,000 people pay capital gains tax. Loyal listener Edward Letham was surprised.

[E]

Surely that can't be right. I have paid capital gains tax in the past and I am by no means a millionaire. So if I pay capital gains tax, then there must be millions who also pay it.

[B]

So is Edward onto something? We asked Dr. Arun Advani, Director of the Centre for Analysis of Taxation and a research fellow at the Institute for Fiscal Studies. He's recently co authored an IFS report on reforming capital gains tax.

[D]

They are right to be suspicious. It's more like 350,000 to 400,000 in any given year. So last year it was about 370,000.

[B]

Wow, that's a big error.

[D]

Quite a lot more.

[A]

Yeah.

[D]

Yeah. I think probably what Andrew Mitchell was identifying is something that is actually an unusual feature of capital gains tax, which is that it is absurdly concentrated, meaning

[B]

that a small Number of people pay most of the tax.

[D]

Yes. And so he was probably remembering the statistic that 12,000 people pay something like two thirds of the tax. And that was probably what he had in his mind and didn't remember that. Well, there are quite a lot of other people who are paying some tax. It's just a much lower level of the capital gains tax.

[B]

Capital gains tax isn't currently a massive revenue raiser for the Treasury. It only raises about 15 billion pounds a year, less than 2% of the total tax take. But could you get more out of it? What would happen if the government just raised capital gains tax rates?

[D]

So HMRC's numbers are that if you were to increase the top rate of capital gains tax by 10 percentage points. So the top rate's currently mostly 20%, although there's a few other rates. If you increase that by 10 percentage points, it's almost a 50% increase. You would think on a base of 14 billion pounds, that should add 7 billion pounds. But actually they forecast that within a couple of years, you're actually losing 2 billion pounds.

[B]

We increase the rate, but end up losing money.

[D]

How come Capital gains tax is paid specifically when you choose to sell the asset that you own. And the thing about that is that you can choose when you sell, so you don't have to sell today or tomorrow. You could choose to hang on to something longer. You could even hang on to it and then leave the country and it'll be completely out of capital gains tax because you can sell after you leave and then we don't charge you, which is unusual because most countries would charge you on the capital gain that you'd built up over the time you'd been. But we don't do that. You can also hang onto it if you're older and you think, actually, I don't need to sell this asset now. You can hang onto it until you die. And when it gets passed on to your heirs, the capital gains tax is wiped out. And so those kinds of behaviors are really important and mean that we think that actually if you increase the rate, there's quite a big in the jargon we call the behavioral response.

[B]

So raising rates alone doesn't get you very far. But what about if the government tried some more comprehensive reform aimed at plugging some of the gaps? Aaron is a man with a plan.

[D]

There are four big things that you'd want to change. The first is the tax rate itself. Currently, that tax rate is much lower, as we described, than income tax rates. And that creates one problem for Growth, which is that people want to set up as individual businesses, not because they really want a fast growing business, but just because they get a lower tax rate for work they would otherwise be doing. So you'd want to equalize that. Alongside that, you want to recognize the fact that actually people are making real investments, putting real cash in, in some cases. And so in those cases, you want to give them an allowance to account for the fact that that cost of investment is actually, you know, a cost of borrowing to them. So you'd want an investment allowance alongside that. The third thing is that there's a gap that currently happens, a leak from capital gains tax. That happens because you, you can hang onto an asset until you die. And by doing that, the gain is completely wiped out. There's no tax. And that also affects your investment incentives as well. So it has negative growth impacts. So you'd want to get rid of that and remove what's called death uplift. You tax capital gains not at the point that somebody dies, but just at the point that the person who inherits the asset sells. At that point, they would be taxed on the whole gain. And finally, you also want to account for the fact that currently people can just completely leave the country. And by doing that, they can get out of the capital gains tax entirely, including on gains they made while they were here. So you'd want to introduce a tax that's called deemed disposal, like Canada or the US or Australia have, that makes sure you tax those capital gains before somebody leaves.

[B]

I don't know how likely Rachel Reeves is to take your advice, but how much do you think she would raise if she did?

[D]

So if you were to implement the full package of reforms, equalization of the tax rates with an investment allowance and closing the two big leaks of being able to hang on till you die or till you leave to get out of the tax together, all of those things would raise another £14 billion. It's almost doubling the size of the tax at the moment.

[B]

Our thanks to Dr. Aaron Advani. The US Election is only a few weeks away, and presidential hopeful Donald Trump has an issue he likes to return to again and again.

[F]

There's so much more crime now. Joe Biden is out the other day trying to claim that crime is down, but actually crime is way up over the world. Crime is down all over the world, except here. Crime here is up and through the roof.

[B]

According to the figures collected by the FBI, crime is down since Donald Trump's last full year in the White House, 2020. From 2020 to the end of 2023, violent crime in general is down between 4 and 6%, and homicides in particular are down between 15 and and 16%, depending on whether you look at the absolute numbers or the crime rates relative to population. Now, those numbers slightly flatter the Biden administration because both violent crime and homicides were unusually high in 2020. Looking back over the last decade or more, the rates of both violent crime and homicides have been gently rising and falling at a substantially lower level than 20 or 30 years ago. So when Trump said crime was up in the presidential debate in September, the debate moderator, ABC's David Muir, fact checked the former president.

[D]

As you know, the FBI says overall

[B]

violent crime is actually coming down in this country. But Trump is sticking to his guns. He says the numbers are skewed by missing statistics from the cities with the worst levels of crime.

[F]

The FBI didn't report the most crime ridden cities. They didn't do it. They left out large numbers of areas where they had a lot of crime.

[B]

This was backed up on Twitter by Trump cheerleader Elon Musk, who retweeted suggestions that big cities with a lot of crime, such as New Orleans and Los Angeles, were not being counted in the figures. Elon's retweet quote comment was, that is bizarre. Why were no homicides reported in cities that have a lot of homicides? So who's right? Are all the crimes being counted? Beth Ashmead Latham has been looking into this. Hello, Beth.

[G]

Hello, Tim.

[B]

So what official information do we have on crime levels in the US well,

[G]

it's gathered by the FBI, but the source is police departments across the country who send the FBI their crime data.

[B]

And do the FBI get data that covers the whole country?

[G]

No, the FBI data has never managed to cover 100% of the country. I spoke to a criminologist from Virginia Commonwealth University, J. Albanese, and he explained why it's so difficult to get all the Data.

[H]

In the US we have approximately 18,000 police departments, which is a rather shocking number. We started as a bunch of independent groups and we have city, town, village police departments, which have never merged together into larger agencies. So collecting crime data is a much bigger administrative task than it is in most places.

[B]

So what proportion of the data is being collected?

[G]

In 2023, 85% of police departments sent in data to the FBI.

[B]

So it's true that some places aren't being counted, but are those the places with lots of crime?

[G]

Well, let's start with population. Although 85% of the law enforcement agencies submitted data in 2023 and that may not seem very high. In fact, it covers 94% of the

[B]

population, which seems to suggest that it's the bigger places that are submitting.

[G]

Seems to, but I'd never come to you with an assumption, Tim. So I checked. The 2023 submissions include all the largest cities in America. The biggest city that is isn't included is Jacksonville, Florida, with a population of just under a million.

[B]

But the really big names, New York, Chicago, Los Angeles, they're all included.

[G]

Yes. And so are places with high crime rates, such as Memphis, St. Louis, Baltimore, Detroit and New Orleans. I checked this too. And the 10 cities with the highest crime rates in the US are all included in the FBI data.

[B]

So we've seen no evidence that the crime hotspots are being left out, but some places are missing from the figures. So is that a particular problem this year?

[I]

No.

[G]

Reporting rates briefly plunged in 2021 when they tried to bring in a new system, but that was just teething problems. In the latest full year data, 85% of law enforcement agencies are covered, and that's the same as in 2020 when Trump was president.

[B]

So it isn't great that the FBI figures aren't covering the whole country, but it doesn't seem to change the fact that crime, and especially homicide, has fallen since and the Trump presidency. Our thanks to Jay Albanese and our own Beth Ashmi Latham. Back in September, Radio 4's Today programme interviewed Dr. Katie Brammell Stainer, Chair of the British Medical Association's committee on GPs, about the pressures that GPs were facing in the UK. During the interview, she said one in

[G]

four GPs knows another GP that has taken their own life.

[B]

Listener Dave Vergason was skeptical and asked us to look more closely at this statistic. And Nathan Gower is with me. Hello, Nathan.

[I]

Hi, Tim.

[B]

And you've been doing just that?

[I]

Yes, I have. So this comes from a survey in 2022 by the Campaign group Rebuild General Practice, who say they represent GPs across Britain. They surveyed about 1300 GPs and asked them the following.

[G]

To what extent do you agree or disagree with the following statements? I know of general practice workers in my region who have taken their own lives due to work pressures.

[I]

As you probably spotted, the question specifically asked about general practice workers who are taking their own lives, not gps. Gps actually make up about a quarter of all staff working in general practice. There are many thousands of nurses, receptionists, healthcare assistants, managers too.

[B]

OK, so Dr. Brammell Stainer misquoted the statistic because it referred to anyone in general practice who'd taken their own life. And that's a much wider group than G. That's right.

[I]

But it's not just the misquote that matters. There are problems with the statistic itself. I spoke to Professor Annette Yechler from the University of Essex. She's an expert in survey design. She said there were some red flags indicating that respondents struggled to answer this question.

[A]

There's a really high rate of people saying don't know. 24% said I don't know in answer to this question. That's huge in the kind of surveys that I work with, socio economic surveys. For most questions, the rate of people saying I don't know or I prefer not to say in response to a question is only around 1%. So tiny.

[I]

Remember the question asked about colleagues in their region who had taken their own life due to work pressures. Well, maybe you're not sure what the definition of a region is, or maybe you know someone who took their own life, but you've got no idea whether it's due to work pressures or not. But there is also a much bigger issue.

[A]

It's likely that, that for one person who takes their own lives, there would be any number of people who would know of that person. That's the wording of the question, right? It's not did you personally know that person? But did you just know of. So yes. So for any one person who took their life, there'd be multiple people here possibly saying, yes, I knew of somebody. So we have no way of mapping the number of people who knew of someone to the number of people who actually took their their own lives.

[B]

So one in four GPs said they knew someone in general practice who'd taken their own life. But the number of people who took their own lives could be 200 or it could be 20. There's no way of knowing exactly.

[I]

You can't reverse engineer the raw number from the survey number. This survey just doesn't tell us very much at all.

[B]

So we've got a claim about suicide in gps, but the claim is based on a survey that wasn't asking just about suicides amongst GPs. And the survey question itself wasn't very good. So, Nathan, do we have any better data?

[I]

We do. The Office for National Statistics compiles numbers on suicide rates by occupation in England. Unfortunately, the most recent Data only covers 2011 to 2015, so it is nearly 10 years out of date. But there will be a new analysis next year. The data doesn't isolate GPS specifically. They're too small a group to generate a reliable rate. But the best category we can look at is one called medical practitioners. So this refers to doctors of all kinds, but not nurses or midwives.

[B]

And what do the data say?

[I]

You have to split it out into the rates for men and women. That's because suicide rates for men generally are much higher than for women. For male doctors, the rate of suicide is about a third lower than men of working age. Generally, for female doctors, it's almost exactly the same as the working age female population. But one suicide expert I spoke to told me that we should still focus on suicide prevention in this group, saying it was a real concern that doctors are dying by suicide while working in close proximity to services that could support them.

[B]

How did suicide rates for doctors compare to those of other professions?

[I]

It can be quite hard to compare to other specific professions, often because there are too few suicides to generate reliable rates. For many individual professions, the ONS either can't provide rates or it marks them as unreliable. You could compare doctors to some other high status professions such as legal professionals. For them, men have a similarly lower risk of suicide and women are at slightly lower risk. But by contrast, in the construction and building trades, male suicide rates are 60% higher than the male working age population, so much higher than doctors. But we should be clear that all this data is just a starting point. The ONS data doesn't demonstrate that the suicides they're recording can be linked to people's professions.

[B]

Thank you, Nathan. For people affected by this issue, you can find details of organisations offering support and advice on the BBC Action Line webpage. The link is on this programme's description page. Loyal listener Frank Fitch has been in touch via more or lessbc.co.uk.

[J]

dear More or less today I heard on the BBC that inflation has dropped below the limit set by the bank of England of 2% for the first time in years. Please would you explain how the bank decides that 2% is the correct value? Also, why we don't try to have no inflation. Thank you for any explanation.

[B]

Thank you, Frank, and I will do my best. The first part of the story is that most economists think that deflation, negative inflation is really bad. If you have debts, for example, a mortgage, they get crushingly big because the price of everything else is falling, including your salary, which is the price of your labour, and of course the price of the house itself. Your 90% mortgage is suddenly 100% mortgage. And deflation is a self reinforcing trap because if the price of everything is falling, nobody wants to spend any money today, they want to wait until later when it's cheaper, which means nobody buys anything and nobody makes anything. And that's a recipe for an economic depression. So that's an immediate reason for an inflation target that isn't zero. You want a margin for error because you want to avoid deflation. Another reason is that in a healthy economy, prices need to adjust up and down. But people are often very reluctant to accept a fall in the price of their labor that is a pay cut. In fact, it's so difficult to cut pay that employers might just sack people instead. And arguably, it would be better to have an economy where people take pay cuts than where people just get fired en masse. If there's a bit of inflation, it's easier to get there. Employers just don't raise pay in line with inflation. It's a nominal pay freeze, but a pay cut in real terms, which is no fun, but perhaps better than the alternative when times are tough. A third reason to aim for a bit of inflation is that it allows the bank of England to boost the economy if a recession is looming. The economy gets a boost if real interest rates are low or even negative. Effectively, you're rewarding people for borrowing money and spending or investing. And how do you get negative real interest rates? Simple. You cut bank of England base rates below the rate of inflation. The higher inflation is, the easier that is to do so. Frank, you might ask, if deflation is so bad and inflation has all of these advantages, why not aim for 3% or 4% or 50% or 100%? Good question. If inflation is, say, 50%, that is a mess. Unions have to renegotiate salaries every few weeks. Shopping becomes a bewildering experience. Nobody really knows what anything costs because money has lost its meaning. Most economists would say that inflation of 2 or 3% doesn't really have any serious costs. You don't need to worry about 2 or 3% inflation when you're negotiating a salary or planning an investment. You don't need to wonder, when you go to the supermarket, whether a price increase is just general inflation or the rise of a price of a particular product. Prices just edge up, your salary edges up, and it's no problem. But why 2% in particular? I don't think there's a reason for that specific number. In fact, after the financial crisis, the chief economist of the International Monetary Fund, Livier Blanchard, suggested that it would be better to 4%. But once these targets have been set, they are very hard to shift. Here on more or less, we Want people to know that it doesn't matter where you are in the world, whether it's the heart of the city or the remotest wilderness. We will pursue and track down any statistic we're asked to. After all, we have a particular set of skills, skills we have acquired over very long careers. We will look for those statistics, we will find those statistics, and we will fact check those statistics. So when loyal listeners Jeremy Pack and Sandra Wilkinson asked us to scrutinise a sign they saw in the rugged beauty of Banff national park in Canada. All snow clad mountains, stunning lakes, we eagerly agreed. The sign ready?

[C]

Did you know that in order for grizzly bears to store enough fat reserves, they eat up to 250,000 buffalo berries a day?

[B]

250,000 buffalo berries a day. This could mean only one thing. We're going on a bear hunt. And there's no better guide for us than Dr. Frank Van Manen, team lead of the Interagency Grizzly Bear Study Team for the United States Geological Service. Cool title. I started by asking Frank, is it really right that grizzly bears eat berries, let alone up to a quarter of a million of them a day?

[C]

They eat a lot of berries? Yeah, depending on what area of their range we're talking about. But in some areas, their diet is really dominated in the fall, especially by berries.

[B]

I'm curious, bears are eating a lot at this time of year to prepare for hibernation, is that right?

[C]

That's correct, yeah. I mean, their whole life history, in a way, is driven by the fact that they spend, you know, five, six, sometimes seven months, depending on what area we're talking about in hibernation. So their whole strategy throughout the active season is to accumulate fat to prepare for hibernation. And so the fall period is what we refer to as the hyperphagia period. That is the period of hyper consumption of foods and just getting the calories.

[B]

And when you say hyper consumption, what does that actually look like?

[C]

That means that some bears will spend upwards of 20 plus hours a day looking for food.

[B]

So among the things that they may eat is the berry, the humble berry. And one of our loyal listeners saw a claim that grizzly bears can eat a quarter of a million buffalo berries a day. Do you recognize that number? Do you know where it might have come from?

[C]

You see that number or, you know, there's also numbers of over 200,000. So somewhere in the range of 200 to 250,000, you see that number quoted quite often. There is this report from a Canadian wildlife biologist by the name of Arthur Pearson. And it's a report on what I consider kind of a classic bear study, in this case, on grizzly bears in the Yukon territory. It's a classic study because it's really one of these naturalist studies where people spend a lot of time in the field studying bears, observing bears, radio collar them, capturing and radio collaring them. What they did, they counted the number of berries in bear scat. And you can imagine that's quite an endeavor.

[B]

That sounds old school. So they're going through bear poop? To be clear, yes.

[I]

Okay.

[C]

They were able to sample 24 scats, bear poop, and they developed an equation from that to determine, based on weight, how many seeds of berries were in those cats.

[B]

I mean, well, how many seeds were there in one dropping?

[C]

So for bears that were primarily consuming these buffalo berries in that area where they were doing this study, they counted over 20,000 berries per scat.

[B]

That is an honest day's work.

[C]

I don't think they counted over 20,000 seeds in each scat. They did it by approximating it by weight.

[B]

For some reason, they decided to take a shortcut. I wonder why. Okay, so you've got 20,000 berries in the scat of a bear that is consuming mostly berries. So how many scats per.

[C]

So it's over 20,000 per scat. And then they determined by following and observing these animals that those animals that were focused on feeding on buffalo berries were producing about 10 scats in a 24 hour time period. Kind of a simple extrapolation from that is that there's over 200,000 buffalo berries consumed in a 24 hour time period.

[B]

I suppose another way of trying to figure out how many berries bears eat is by figuring out how many calories bears need and then how many calories there are per berry. So has anybody done that calculation?

[C]

I actually did that. And so if we go by what the daily need for kilocalories is for bears during hyperphagia, during that period of time of food consumption in the fall, it's typically about 20,000. So 20,000 kilocalories per day. We know that per gram of buffalo berries, of dry weight, it produces 3.26 kilocalories. So from that we can calculate the total dry weight of berries that is needed. And so that amounts to 6,135 grams. So basically 6.1 kilograms of dry weight of berries. And since we also have an estimate from that Pearson study in 1975, that digestible dry weight per berry is 0.0307 grams, we can determine how many berries make up a total dry weight of 6.1 kilograms. And that number comes out to be 199,836.

[B]

Oh, wow. So that's a totally different way of estimating how many berries they eat and it basically gets you to the same number. 200,000.

[C]

Exactly. Yeah. It's for me, it kind of gave me the confidence to say that those estimates were probably pretty reasonable.

[B]

Our thanks to Dr. Frank Van Manen. That is all we have time for this week, but please keep your questions and comments coming in. The email, as always, is more or lessbc.co.uk. we will be back for the last episode in this series next week. Until then, goodbye. More or Less was presented by me, Tim Harford. It was produced by Tom Coles with Bethan Ashmead Latham and Nathan Gower. The production coordinator was Katie Morrison. The program was mixed by Rod Farker and our editor is Richard Varden.

[E]

Hello, Russell Caine here. I used to love British history. Be proud of it. Henry viii, Queen Victoria, massive fan of stand up comedians, obviously, Bill Hicks, Richard Pryor. That has become much more challenging for I am the host of BBC Radio 4's Evil Genius, the show where we take heroes and villains from history and try to work out were they evil or genius. Do not catch up on BBC Sounds by searching Evil Genius. If you don't want to see your heroes destroyed, but if like me, you quite enjoy it, have a little search. Listen to Evil Genius with me, Russell Cain. Go to BBC Sounds and have your world destroyed.