1 00:00:00,000 --> 00:00:06,000 So what's up? Will the treehouse detectives find any endangered animals in Jacob's backyard? 2 00:00:06,000 --> 00:00:09,000 Will Kaylee get her Girl Scout badge? 3 00:00:09,000 --> 00:00:13,000 What else should the detectives do to help Jacob get a certified habitat? 4 00:00:13,000 --> 00:00:18,000 Find out in the next exciting chapter of The Case of the Zany Animal Antics. 5 00:00:20,000 --> 00:00:23,000 Be sure to look for answers to the following questions. 6 00:00:23,000 --> 00:00:25,000 What is carrying capacity? 7 00:00:25,000 --> 00:00:28,000 Why is it important to randomly sample a population? 8 00:00:28,000 --> 00:00:30,000 What makes a good habitat? 9 00:00:30,000 --> 00:00:32,000 What does territorial mean? 10 00:00:34,000 --> 00:00:37,000 Thanks for helping me on my bat project, Dr. D. 11 00:00:37,000 --> 00:00:41,000 Helping an endangered species is one of the requirements for my wilderness badge. 12 00:00:41,000 --> 00:00:44,000 No problem. I'm glad that your project involves bats, 13 00:00:44,000 --> 00:00:47,000 because over 40% of bat species are endangered or threatened. 14 00:00:47,000 --> 00:00:51,000 It's especially important because the eastern big-eared bat, 15 00:00:51,000 --> 00:00:54,000 which is native to southeastern Virginia, is endangered. 16 00:00:54,000 --> 00:00:56,000 I heard that as well. 17 00:00:56,000 --> 00:01:01,000 Did you know that one bat can eat up to 3,000 insects in one night? 18 00:01:01,000 --> 00:01:04,000 It can also help to disperse seeds and pollinate fruits. 19 00:01:04,000 --> 00:01:08,000 So by providing the bats with shelter and a place to raise their young, 20 00:01:08,000 --> 00:01:11,000 the number of bats in the area should increase. 21 00:01:11,000 --> 00:01:15,000 It will certainly help, but a lot of factors affect the growth of a population. 22 00:01:15,000 --> 00:01:20,000 Isn't a population a group of the same species that's living in a particular area? 23 00:01:20,000 --> 00:01:22,000 I see that you've been doing some research. 24 00:01:22,000 --> 00:01:26,000 Let's do an experiment with pennies that simulates population growth. 25 00:01:26,000 --> 00:01:31,000 If I throw down eight pennies to represent eight bats, how many will turn up heads? 26 00:01:31,000 --> 00:01:33,000 On the average, four should turn up as heads. 27 00:01:33,000 --> 00:01:36,000 That's right. Let's say that the bat population as a whole 28 00:01:36,000 --> 00:01:40,000 averages one baby or pup per bat couple per year. 29 00:01:40,000 --> 00:01:43,000 That means that with four bat couples or eight bats, 30 00:01:43,000 --> 00:01:46,000 they would produce a total of four pups per year, 31 00:01:46,000 --> 00:01:48,000 which means after one year you would have 12 bats. 32 00:01:48,000 --> 00:01:52,000 Excellent. We can then add four pennies and throw down a total of 12 33 00:01:52,000 --> 00:01:54,000 to see how many bats we'll have in the next year. 34 00:01:54,000 --> 00:01:58,000 Let's try to experiment five times to see how many bats we'll have in five years. 35 00:02:01,000 --> 00:02:03,000 We've got five heads. 36 00:02:05,000 --> 00:02:07,000 Add five pennies to mine. 37 00:02:19,000 --> 00:02:23,000 I get 45. The population increased rapidly. 38 00:02:23,000 --> 00:02:28,000 I have 62. It's different because you don't always get the average when you throw down pennies. 39 00:02:28,000 --> 00:02:33,000 Shouldn't we subtract a few pennies to represent the bats that died or left the area? 40 00:02:33,000 --> 00:02:38,000 That's a good point. Under ideal conditions where bats only die of old age and no bats immigrate, 41 00:02:38,000 --> 00:02:43,000 the population will eventually reach what's called its biotic potential as it grows very rapidly. 42 00:02:43,000 --> 00:02:47,000 I guess that means that the animals' needs are met and that they have a healthy habitat. 43 00:02:47,000 --> 00:02:52,000 That's right. In the real world, the population will eventually reach an equilibrium situation 44 00:02:52,000 --> 00:02:55,000 where the number of births equal the number of deaths. 45 00:02:55,000 --> 00:03:00,000 I guess that's because the population gets so big there's just not enough food to feed everyone. 46 00:03:00,000 --> 00:03:03,000 That's one factor, but there are a lot of other factors. 47 00:03:03,000 --> 00:03:06,000 A lot of animals in a small area is called a high density. 48 00:03:06,000 --> 00:03:09,000 High densities of prey attract more predators. 49 00:03:09,000 --> 00:03:14,000 And I would think that diseases would spread more easily through high density populations. 50 00:03:14,000 --> 00:03:17,000 Plus, I guess that animals just need a certain amount of space. 51 00:03:17,000 --> 00:03:22,000 That's right. All of these factors affect the maximum number of a species that a given environment can support. 52 00:03:22,000 --> 00:03:25,000 That's called the carrying capacity. 53 00:03:25,000 --> 00:03:28,000 I just hope we can help increase the bat population. 54 00:03:28,000 --> 00:03:33,000 I hope so, too. So how can you tell if the population is shrinking or growing? 55 00:03:33,000 --> 00:03:38,000 We would have to count them, but I would think it would be almost impossible to count all of the animals. 56 00:03:38,000 --> 00:03:42,000 Yes, it would be difficult. In order to estimate the population of a species, 57 00:03:42,000 --> 00:03:46,000 scientists will capture some of them, mark them with a tag, and then release them. 58 00:03:46,000 --> 00:03:50,000 Some time later, they will capture some more of the same species and see what fraction are tagged. 59 00:03:50,000 --> 00:03:54,000 I bet there's some mathematical way to figure out the size of the total population. 60 00:03:54,000 --> 00:03:57,000 There are some other techniques to measure populations. 61 00:03:57,000 --> 00:04:02,000 Right on the Internet, the Carroll City Elementary School in Miami, Florida is investigating a random sampling technique. 62 00:04:02,000 --> 00:04:05,000 Aren't they a NASA Explore School? 63 00:04:05,000 --> 00:04:11,000 To find out how you can get your school to become a NASA Explore School, visit the NASA Sci-Files website. 64 00:04:11,000 --> 00:04:15,000 Yes, and they're working with the Society of Women Engineers. 65 00:04:15,000 --> 00:04:17,000 Here they are now. 66 00:04:17,000 --> 00:04:21,000 Hi, I'm Ta'Quinn, and I'm from Ms. Belanco's class. 67 00:04:21,000 --> 00:04:26,000 And I'm Anita, and I'm in Ms. Gant's class here at Carroll City Elementary School in Miami, Florida. 68 00:04:26,000 --> 00:04:30,000 Hi, Dr. D told us about your investigation. Can you tell us about it? 69 00:04:30,000 --> 00:04:33,000 Sure. With the help from our mentors from the Society of Women Engineers, 70 00:04:33,000 --> 00:04:37,000 we begin by looking at this critter page and trying to predict how many critters are on it. 71 00:04:37,000 --> 00:04:40,000 It looks like it has a lot of critters. 72 00:04:40,000 --> 00:04:44,000 Yes, it's a lot to count, so we brainstormed some ways to estimate the number. 73 00:04:44,000 --> 00:04:47,000 We decided to use a random sampling technique. 74 00:04:47,000 --> 00:04:51,000 Right, we used a sampling square and randomly dropped it on the page of critters. 75 00:04:51,000 --> 00:04:53,000 Why did you drop it randomly? 76 00:04:53,000 --> 00:04:57,000 Randomly dropping the square gives a better sample of the population. 77 00:04:57,000 --> 00:05:00,000 If you choose where to count the critters, you may pick areas with lots of them. 78 00:05:00,000 --> 00:05:02,000 Then your estimate will be too high. 79 00:05:02,000 --> 00:05:05,000 Next, we outlined the square and then counted the number of critters in it. 80 00:05:05,000 --> 00:05:09,000 What do you do if a square cuts a critter in half? How do you count it? 81 00:05:09,000 --> 00:05:14,000 Good question. For our sample, we only used critters that were at least half in the square. 82 00:05:14,000 --> 00:05:16,000 So how many samples did you take? 83 00:05:16,000 --> 00:05:21,000 Remember, in a random sample, the more data you collect, the more accurate your estimate. 84 00:05:21,000 --> 00:05:23,000 We dropped the square four more times. 85 00:05:23,000 --> 00:05:26,000 Next, we found the average number of critters per square unit. 86 00:05:26,000 --> 00:05:29,000 How did you find the total number of critters? 87 00:05:29,000 --> 00:05:33,000 We counted the number of square units on the page, and there were 63. 88 00:05:33,000 --> 00:05:37,000 So we multiplied our average number by 63 and recorded it on our chart. 89 00:05:37,000 --> 00:05:43,000 To give us an even more accurate estimate, we used each group's average and calculated the class average. 90 00:05:43,000 --> 00:05:45,000 How do you know if your estimates are accurate? 91 00:05:45,000 --> 00:05:48,000 Don't you need to know the total number of critters on the page? 92 00:05:48,000 --> 00:05:51,000 Yes, we each counted the critters and compared our answers. 93 00:05:51,000 --> 00:05:54,000 There were 393 critters on the page. 94 00:05:54,000 --> 00:05:57,000 How did your estimates compare with the actual numbers? 95 00:05:57,000 --> 00:06:00,000 Our group estimated 433, so we were off by 40. 96 00:06:00,000 --> 00:06:05,000 However, when we compared the class estimate to the actual, it was 412, a lot closer. 97 00:06:05,000 --> 00:06:09,000 That's why it's important to take lots of samples and gather plenty of data. 98 00:06:09,000 --> 00:06:13,000 It is very difficult to count a large population of animals, 99 00:06:13,000 --> 00:06:17,000 but by sampling and finding an estimate, you can get pretty close to the number. 100 00:06:17,000 --> 00:06:21,000 Next, we're going outside to do a sample of some real critters, like grasshoppers. 101 00:06:21,000 --> 00:06:25,000 Sounds like fun. Maybe we should do that for Jacob's backyard. 102 00:06:25,000 --> 00:06:29,000 Be sure to post your results on the website so we can see what you found. 103 00:06:29,000 --> 00:06:33,000 Will do, and let us know about the animal population in your preserve. 104 00:06:33,000 --> 00:06:36,000 Goodbye from Carroll City Elementary School in Miami, Florida. 105 00:06:38,000 --> 00:06:42,000 I'm not sure that Jacob will want to know the population of critters in his backyard. 106 00:06:42,000 --> 00:06:47,000 Probably not, but at least you have an idea of how to find the size of a population. 107 00:06:47,000 --> 00:06:51,000 I wonder how Jacob's doing. Maybe I should go see if he needs some help. 108 00:06:51,000 --> 00:06:54,000 Well, this will take some time to dry. 109 00:07:17,000 --> 00:07:19,000 Whoa! 110 00:07:42,000 --> 00:07:44,000 Have you heard from Jacob? 111 00:07:44,000 --> 00:07:47,000 I wonder if he's working in his backyard. 112 00:07:47,000 --> 00:07:50,000 No, but Kaylee's report on populations was very helpful. 113 00:07:50,000 --> 00:07:53,000 She's almost done all of her work to earn her badge. 114 00:07:53,000 --> 00:07:56,000 All she needs is to find out about an endangered species in our state. 115 00:07:56,000 --> 00:07:59,000 I wonder if there's one in Jacob's backyard. 116 00:07:59,000 --> 00:08:02,000 I think everything in Jacob's backyard is endangered. 117 00:08:02,000 --> 00:08:07,000 I know, but if we could find a species that his backyard could support, maybe we could help Kaylee. 118 00:08:07,000 --> 00:08:09,000 That would be awesome. Let's go to the problem board. 119 00:08:09,000 --> 00:08:11,000 Good idea. 120 00:08:11,000 --> 00:08:13,000 So what do we know? 121 00:08:13,000 --> 00:08:17,000 We know that animals belong to the animal kingdom and are divided into two separate divisions. 122 00:08:17,000 --> 00:08:19,000 Right, vertebrates and invertebrates. 123 00:08:19,000 --> 00:08:23,000 We know that animals have basic needs and that they will migrate to find new food sources. 124 00:08:23,000 --> 00:08:28,000 We also know that animals reproduce based on the amount of food available and the right conditions. 125 00:08:28,000 --> 00:08:30,000 That's why populations will vary so much. 126 00:08:30,000 --> 00:08:32,000 So what do we need to know? 127 00:08:32,000 --> 00:08:34,000 We need to know what makes a good habitat. 128 00:08:34,000 --> 00:08:38,000 We also need to learn more about how habitats can help endangered species. 129 00:08:38,000 --> 00:08:40,000 So where do we go? 130 00:08:40,000 --> 00:08:44,000 Dr. Mota mentioned that Dr. Brenninger studies and protects the wildlife at NASA Kennedy. 131 00:08:44,000 --> 00:08:46,000 I'll see if he can help. 132 00:08:46,000 --> 00:08:51,000 Great. Since we're going to be creating a habitat that can support wildlife and possibly even an endangered species, 133 00:08:51,000 --> 00:08:53,000 we'll need to know what makes up a good one. 134 00:08:53,000 --> 00:08:55,000 Exactly. Here's Dr. Brenninger now. 135 00:08:55,000 --> 00:09:01,000 Hi, I read your email and I understand that Jacob wants to turn his backyard into a nature preserve. 136 00:09:01,000 --> 00:09:05,000 Yes, but we need to learn more about habitats before he does. 137 00:09:05,000 --> 00:09:07,000 What exactly is a habitat? 138 00:09:07,000 --> 00:09:12,000 An area with specific habitat features that allows a specific species to survive. 139 00:09:12,000 --> 00:09:18,000 For example, this area has loess trees and a sparse tree canopy and is called scrubby flatwoods. 140 00:09:18,000 --> 00:09:20,000 So what makes a good habitat? 141 00:09:20,000 --> 00:09:26,000 Lots of things. Habitat should provide enough food, shelter, and protection from predators. 142 00:09:26,000 --> 00:09:32,000 When all these things are present, animals can produce enough young for their population to survive. 143 00:09:32,000 --> 00:09:35,000 Does a species ever produce too many young? 144 00:09:35,000 --> 00:09:37,000 Yes, and that makes the habitat overcrowded. 145 00:09:37,000 --> 00:09:45,000 In fact, some animals will leave and find less crowded areas, while others will stay but will produce fewer young. 146 00:09:45,000 --> 00:09:49,000 So the size and health of a habitat can determine the population of a species? 147 00:09:49,000 --> 00:09:55,000 Exactly. Each individual or family of animals needs enough habitat to survive. 148 00:09:55,000 --> 00:10:02,000 Depending on the amount of food, water, and shelter in a habitat, only a certain number of individuals can be supported. 149 00:10:02,000 --> 00:10:09,000 If the habitat cannot provide for a large enough population, the species faces extinction. 150 00:10:09,000 --> 00:10:10,000 What do you mean? 151 00:10:10,000 --> 00:10:14,000 In a species, there are years when there are more deaths than births. 152 00:10:14,000 --> 00:10:20,000 There are also times when the habitat is disrupted by disease, fire, and storms. 153 00:10:20,000 --> 00:10:23,000 But won't they just reproduce once the habitat is restored? 154 00:10:24,000 --> 00:10:34,000 If the disruption causes the population to decrease, then the probability that enough individuals will survive to reproduce is less likely. 155 00:10:34,000 --> 00:10:37,000 How much habitat does each species need? 156 00:10:37,000 --> 00:10:43,000 That varies among species. Florida scrub jays need about 25 acres, and they're very territorial. 157 00:10:43,000 --> 00:10:45,000 What is territorial? 158 00:10:45,000 --> 00:10:55,000 Territorial means that they claim a specific area of their own. If other scrub jays try to live in their area, they will defend it. 159 00:10:55,000 --> 00:10:58,000 I never thought of birds defending their home. 160 00:10:58,000 --> 00:11:06,000 Scrub jays live within the same territory with their mate for life. Their young also often stay with them for many years. 161 00:11:06,000 --> 00:11:10,000 So how are habitats destroyed or disrupted? 162 00:11:10,000 --> 00:11:16,000 Fires and storms regularly can change habitat but seldom destroy them. 163 00:11:16,000 --> 00:11:22,000 Humans, however, regularly destroy habitats to build houses and grow food. 164 00:11:22,000 --> 00:11:26,000 They also disrupt natural processes such as wildfires. 165 00:11:26,000 --> 00:11:28,000 Why is fire so important? 166 00:11:28,000 --> 00:11:32,000 Fires keep the shrubs low and add nutrients back into the soil. 167 00:11:32,000 --> 00:11:35,000 How do you help NASA protect the environment? 168 00:11:35,000 --> 00:11:42,000 I use field studies, remote sensing, and computer models to study animal populations and their habitat. 169 00:11:42,000 --> 00:11:47,000 I then advise NASA on how to take care of the environment. 170 00:11:47,000 --> 00:11:50,000 NASA sure is concerned about the environment. 171 00:11:50,000 --> 00:11:57,000 That's right, and we want to make sure that endangered animals such as scrub jays are around for a long time. 172 00:11:57,000 --> 00:12:00,000 Thanks, Mr. Brenninger. This has been helpful. 173 00:12:00,000 --> 00:12:03,000 You're welcome, and good luck on your nature preserve. 174 00:12:03,000 --> 00:12:08,000 Wow, I never realized how difficult it was to protect habitats and endangered species. 175 00:12:08,000 --> 00:12:11,000 That's why it's such a great idea to create a backyard habitat. 176 00:12:11,000 --> 00:12:13,000 Just think of what you can do to help animals. 177 00:12:13,000 --> 00:12:16,000 Do you really think we can actually help an endangered species? 178 00:12:16,000 --> 00:12:18,000 Well, we can try. 179 00:12:18,000 --> 00:12:24,000 In fact, now that we've done the research, we may be ready to start learning about protecting animals in the backyard habitat. 180 00:12:24,000 --> 00:12:26,000 Great, I hope we can help.