1 00:00:00,330 --> 00:00:05,640 Hello, my name's Lindsay Turnbull and I'm an associate professor in the Department of Plant Sciences 2 00:00:05,640 --> 00:00:10,770 at the University of Oxford, and we're right in the middle of this very serious corona virus crisis right 3 00:00:10,770 --> 00:00:15,810 now. And my students are all stuck at home and we want to keep them in touch with biology 4 00:00:15,810 --> 00:00:21,240 and keep in touch with us. And so we're going to make a new series of videos and they're going to be called back garden 5 00:00:21,240 --> 00:00:46,460 biology. 6 00:00:46,460 --> 00:00:51,530 Hello, welcome to this episode of Golden Biology, and it's an incredibly hot, sunny day in 7 00:00:51,530 --> 00:00:56,750 a very, very dry month of May, and I'm sure you're finding the same in your garden, having to do a lot of watering 8 00:00:56,750 --> 00:01:02,060 and so on. For the first time, this episode is going to be centred on birds. 9 00:01:02,060 --> 00:01:08,060 I've kind of avoided that because it's very difficult to take good footage of birds unless you've really got a good camera, 10 00:01:08,060 --> 00:01:13,100 which I don't really have. But I was able through the very kind agreement of some of my 11 00:01:13,100 --> 00:01:18,320 colleagues to borrow some footage. So you're gonna see a mixture of footage. Some of it is sort of fairly poor 12 00:01:18,320 --> 00:01:23,900 quality. And that's my footage taken in my garden, but also some much better. Close-Up shots 13 00:01:23,900 --> 00:01:29,020 may have been taken by colleagues in the zoology department who work up at White Wighton Woods 14 00:01:29,020 --> 00:01:34,160 and White and Woods is really famous for the study of great [INAUDIBLE] and bleated. So 15 00:01:34,160 --> 00:01:39,230 they've been monitoring both great [INAUDIBLE] and blue [INAUDIBLE] at Weitzen for about 60 16 00:01:39,230 --> 00:01:44,320 years. And that makes it one of the longest running ecological studies in the country, possibly 17 00:01:44,320 --> 00:01:49,430 in the world. Now, I was inspired by that because I put up a nest box in my garden, as I'm 18 00:01:49,430 --> 00:01:54,470 sure many of you have done. If we just pan over behind me, we can hopefully see it. So that is a 19 00:01:54,470 --> 00:01:59,750 brand new nest box that I was given for as a Christmas present. And we decided 20 00:01:59,750 --> 00:02:05,600 to put that up just the day after lockdown. And to be honest, we thought we're probably going to be too late 21 00:02:05,600 --> 00:02:10,730 to have anything use it this year. But within 24 hours of putting that 22 00:02:10,730 --> 00:02:16,400 nest box up, a pair of blue [INAUDIBLE] arrived and started checking it out because we were really delighted about 23 00:02:16,400 --> 00:02:21,500 and in fact, they've just finished and all left has nothing, no sound coming from there anymore. 24 00:02:21,500 --> 00:02:26,540 So I want to just talk you through what is the nesting behaviour of the blue [INAUDIBLE]? How long does 25 00:02:26,540 --> 00:02:33,170 it take? What do they do? How many eggs do they lay? And they're going to look at some of that and a bit more detail. 26 00:02:33,170 --> 00:02:38,330 So it begins in about February for blue [INAUDIBLE]. They start looking for nest sites. 27 00:02:38,330 --> 00:02:43,490 Obviously, our two have not been very successful, haven't really found anywhere that they like that much. And that's 28 00:02:43,490 --> 00:02:49,340 why they had to wait a bit late and as soon as they saw that they were in there. Now the female alone 29 00:02:49,340 --> 00:02:54,410 will first start to build the nest. She's not going just layer actions to the bottom of that box and she collects 30 00:02:54,410 --> 00:02:59,450 Moss to do that. So we saw her actually in the lawn pulling up moss and bringing it 31 00:02:59,450 --> 00:03:04,610 back and polluted make, you know, as all animals are sort of individuals. They didn't all make 32 00:03:04,610 --> 00:03:10,220 an identical nest. Some of them build a thick layer of moss that just a few feathers on the top. 33 00:03:10,220 --> 00:03:15,290 Some of them have a thin layer of loss with a great big carpet of feathers on the top. But Bluett is very 34 00:03:15,290 --> 00:03:21,350 fond of feathers for the tops of their nests. And those examples were from Wighton, 35 00:03:21,350 --> 00:03:26,480 where the researchers are going in and having to monitor the nest very closely. And that takes 36 00:03:26,480 --> 00:03:31,770 the female bullshit about two weeks. And she probably won't get any help from the male in doing it. 37 00:03:31,770 --> 00:03:36,950 And once she's happy with that and she's got it built, she starts to lay her eggs and she will lay 38 00:03:36,950 --> 00:03:42,170 one egg every day until she has her clutch. And only then will she start to 39 00:03:42,170 --> 00:03:47,180 incubate the eggs. And to do that, she'll actually still strip off some of the feathers from her 40 00:03:47,180 --> 00:03:52,540 belly so she can press her bare skin against the eggs and transfer warmth to them. 41 00:03:52,540 --> 00:03:57,590 And she has to incubate them for around two weeks. And when that's processes finished out will 42 00:03:57,590 --> 00:04:02,840 emerge these tiny sorts of pink, helpless chicks that look a bit ugly, to be honest, like a little newborn 43 00:04:02,840 --> 00:04:08,090 mouse or something very helpless, obviously needing a lot of help from the parents. And that's 44 00:04:08,090 --> 00:04:13,730 when we really started to notice them, because then we realised that the two parents have to work like crazy. 45 00:04:13,730 --> 00:04:18,800 Each one of those chicks can eat up to 100 caterpillars a day 46 00:04:18,800 --> 00:04:23,900 in order to grow as fast as they need to. So both parents are backwards and forwards in and out 47 00:04:23,900 --> 00:04:29,150 of the box to the point where sometimes one parent would arrive as the other are leaving and have to sort of bounce 48 00:04:29,150 --> 00:04:34,570 off in mid-air before it could even get in and feed them. So you see how hard they are working. 49 00:04:34,570 --> 00:04:39,710 And in fact, it's been estimated that birds who are rearing chicks are working 50 00:04:39,710 --> 00:04:44,720 as hard as a Tour de France cyclist. So it's the equivalent of doing the Tour de France as a human. If you're a 51 00:04:44,720 --> 00:04:49,760 bird trying to to raise offspring, it's hugely energetically demanding. And what 52 00:04:49,760 --> 00:04:54,890 you may have noticed, irrespective of whether you actually have a nest box in your garden, is there's a period of time 53 00:04:54,890 --> 00:04:59,990 for about a week when Blue Tech seemed to be launching themselves at the windows of your house. And I managed 54 00:04:59,990 --> 00:05:05,210 to film this one in the front of my house when I was actually staking out the sparrows last week. 55 00:05:05,210 --> 00:05:11,730 And you can see them going all around the windows and behind the drainpipes and they are looking for spiders. 56 00:05:11,730 --> 00:05:16,970 And people have always noticed this about its blue [INAUDIBLE]. And great is that they start feeding chicks spiders 57 00:05:16,970 --> 00:05:22,190 at a critical period. And they wondered why. And someone did a really nice study to investigate 58 00:05:22,190 --> 00:05:27,290 it. So proteins, which are the molecules that are the building blocks of all organisms, are made 59 00:05:27,290 --> 00:05:32,390 up of things called amino acids. And there were 20 different ones. And some of them are harder to obtain 60 00:05:32,390 --> 00:05:37,550 than others. And spiders are peculiarly rich in a particular amino 61 00:05:37,550 --> 00:05:42,800 acid. And so somebody did a study where they gave bluechip chicks a supplement which contained 62 00:05:42,800 --> 00:05:48,030 this amino acid to see what impact did it have. And it affected their behaviour as the chick wants 63 00:05:48,030 --> 00:05:53,310 the chicks fledge and were older. So it made them bolder and more inquisitive and investigative. 64 00:05:53,310 --> 00:05:58,590 So that behaviour of looking for spiders is really kind of to protect the mental 65 00:05:58,590 --> 00:06:03,660 developments, if you like, off their chicks. Now, once the chicks, about 14 weeks old, they 66 00:06:03,660 --> 00:06:08,760 looked like they're sorry, 14 days old, just two weeks later, they look like this. You can see they've got 67 00:06:08,760 --> 00:06:13,800 lots of feathers on the man nearly ready to go. And then the parents change their behaviour about it. 68 00:06:13,800 --> 00:06:19,440 And when they arrive at the box, as you can see here, they start shaking quite a lot 69 00:06:19,440 --> 00:06:24,570 like this. And that's that kind of aggressive shouting, get out of that box. You know, you need 70 00:06:24,570 --> 00:06:29,610 to head. We need to get out of here so I can start feeding you properly. And they 71 00:06:29,610 --> 00:06:35,370 will keep feeding the chicks. The parents will stay with them. I don't know quite where they've gone. I don't see them around the garden. No, 72 00:06:35,370 --> 00:06:40,590 but they will continue to look after them for another few weeks. That's the pinch point for bleated 73 00:06:40,590 --> 00:06:45,810 chicks, the young ones. Are they going to make it? They've got to fatten up. They've got to make it through the winter. 74 00:06:45,810 --> 00:06:51,360 Of course, most of them won't, because a lot of chicks are born every year. So the bleated 75 00:06:51,360 --> 00:06:56,490 average klatsch size is about seven, but it can be a lot more. And that's the thing that we're going to look at 76 00:06:56,490 --> 00:07:01,650 in a lot more detail today. Why is it that different birds have different 77 00:07:01,650 --> 00:07:06,830 sizes of clutch? And what factors determines that? 78 00:07:06,830 --> 00:07:11,940 So I got through a made. Three little helpers here, but great. It's not. It's because more of the 79 00:07:11,940 --> 00:07:16,950 work that I'm going to talk about has actually been done with great [INAUDIBLE] rather than blue [INAUDIBLE]. There wasn't I 80 00:07:16,950 --> 00:07:21,990 didn't have any. They played I honestly. Going to think about a life history 81 00:07:21,990 --> 00:07:27,120 trait and a life history trait is a characteristic of a species that's 82 00:07:27,120 --> 00:07:32,190 not a physical characteristic. So a physical characteristic might be something like wing length 83 00:07:32,190 --> 00:07:37,500 or beak length, but a life history trait is something to do with the way 84 00:07:37,500 --> 00:07:43,160 the bird lives its life. So it might be how long it lives. Lifespan is a life history trait, 85 00:07:43,160 --> 00:07:48,450 or it might be the number of eggs that it lays. Or it might be. How much care it then gives to those 86 00:07:48,450 --> 00:07:53,730 chicks when they hatch. Those are all examples of life history traits and whether traits are physical 87 00:07:53,730 --> 00:07:58,770 or whether their life history traits. We believe as ecologists and evolutionary biologists that 88 00:07:58,770 --> 00:08:04,110 all those traits are under natural selection and natural selection is a force 89 00:08:04,110 --> 00:08:09,810 that shapes organisms. And it doesn't just shake the way they look, but it also shapes the way they behave. 90 00:08:09,810 --> 00:08:15,150 I can also understand that a little bit better what natural selection is and how it works. 91 00:08:15,150 --> 00:08:20,550 We're going to hear a little bit from Professor Stuart West, who is a professor of evolutionary biology 92 00:08:20,550 --> 00:08:26,130 in the Department of Zoology here in Oxford. The theory of natural selection 93 00:08:26,130 --> 00:08:31,740 is Darwin's greatest contribution to science, and it follows him just three simple ingredients. 94 00:08:31,740 --> 00:08:36,780 First of those is variation. And all that means is that within a population of 95 00:08:36,780 --> 00:08:41,910 something, you see variation. So, for example, if you're looking at giraffes, some might have 96 00:08:41,910 --> 00:08:46,980 longer names. Some might have shorter legs. The second ingredient needs is 97 00:08:46,980 --> 00:08:51,990 heritability. And what that means is the offspring are like parents. So to go back to 98 00:08:51,990 --> 00:08:57,030 the giraffe example, giraffes with longer necks have offspring, belongingness, 99 00:08:57,030 --> 00:09:02,070 leks, their babies are bigger things. Now, the third thing is slightly more 100 00:09:02,070 --> 00:09:07,440 complicated thing is that you need differential success or differential fitness 101 00:09:07,440 --> 00:09:13,170 limited to the linked variation. And what that means 102 00:09:13,170 --> 00:09:18,690 is the individuals that are different, that have vary in their ability 103 00:09:18,690 --> 00:09:23,790 to survive and reproduce. So again, if we go back to the giraffe example we 104 00:09:23,790 --> 00:09:29,130 might find is the giraffes. Longer necks are better reaching out for trees. 105 00:09:29,130 --> 00:09:34,350 They get more food. They're able to have offspring more successfully. So they end up having more offspring, 106 00:09:34,350 --> 00:09:39,810 then draws shorter necks and evolutionary biology. We sort of lump all these things, 107 00:09:39,810 --> 00:09:44,970 link your ability to survive and reproduce into a term called fitness. So this might be your ability 108 00:09:44,970 --> 00:09:49,980 to cut food, aid, predators, anything like that. Okay, 109 00:09:49,980 --> 00:09:55,200 so now we found out a little bit more about natural selection and how it tends to maximise 110 00:09:55,200 --> 00:10:00,300 something called fitness, which we can say is probably best approximated by the number 111 00:10:00,300 --> 00:10:05,370 of grandchildren that an organism has. Now, let's have a look at Harper's, 112 00:10:05,370 --> 00:10:10,430 because something exciting has happened to them since we last saw them. All three of them have dealt log 113 00:10:10,430 --> 00:10:15,840 and they've all got five eggs in them. I want you to imagine that five is the standard 114 00:10:15,840 --> 00:10:20,880 number of eggs. That's a great tip. I don't think it is. In reality, it's more like seven. But I couldn't fit seven eggs 115 00:10:20,880 --> 00:10:25,980 into my little nest. And what we're going to do is to try to understand if five 116 00:10:25,980 --> 00:10:31,410 is the average that we observe, is that actually the clutch size that will maximise 117 00:10:31,410 --> 00:10:36,930 their fitness. And one way we can test that is to change the number of eggs 118 00:10:36,930 --> 00:10:42,030 that the birds have. By adding extra ones. So I could go to another bird's nest and I 119 00:10:42,030 --> 00:10:47,190 could give this bird one extra egg. And similarly for this bird, I could perhaps 120 00:10:47,190 --> 00:10:52,230 give it two extra eggs and then I could allow it to reach those extra eggs 121 00:10:52,230 --> 00:10:57,390 and see how many chicks does it successfully rear. And when people do things 122 00:10:57,390 --> 00:11:02,970 like this with birds, they tend to find that they are able to reia more chicks 123 00:11:02,970 --> 00:11:08,040 than they would have tonight. They are able to reach those extra chicks. So it looks like their fitness 124 00:11:08,040 --> 00:11:13,080 could actually be higher if they laid more eggs, which of course raises the question then why don't 125 00:11:13,080 --> 00:11:18,090 they lay more eggs on? One of the criticisms of those studies is that it hasn't taken 126 00:11:18,090 --> 00:11:23,190 into account properly of all of the costs of egg laying. So if you just 127 00:11:23,190 --> 00:11:28,290 give a bird an egg that some offer bird has laid and they haven't paid the full costs of 128 00:11:28,290 --> 00:11:34,290 it because they didn't have to manufacture the egg and perhaps they an incubator for quite as long. 129 00:11:34,290 --> 00:11:39,300 The other thing that we haven't taken account of is that birds don't just live for one year. The 130 00:11:39,300 --> 00:11:44,550 females might survive the winter. They have a reasonable chance of doing that. And they might have a higher 131 00:11:44,550 --> 00:11:49,860 chance of doing that if they didn't have a very large number of eggs. Because the bigger the clutch, 132 00:11:49,860 --> 00:11:55,290 the more food they have to find, the more tired they're going to be, the more rundown they're going to get. 133 00:11:55,290 --> 00:12:00,540 So we have to think about the future offspring as well and whether they're being compromised. 134 00:12:00,540 --> 00:12:05,580 So one way of doing this is a really nice study that did this instead. So they again started off. 135 00:12:05,580 --> 00:12:11,160 With three different treatments, so they have their control birds, which would be laying exactly five eggs. 136 00:12:11,160 --> 00:12:16,650 Then they found other birds who had clutches of five and they manipulated them in the following way. 137 00:12:16,650 --> 00:12:21,810 So to some of them, they simply gave them to free eggs. So this one gets free, 138 00:12:21,810 --> 00:12:26,820 actually didn't have to lay them. But she has got to incubate them and rear them 139 00:12:26,820 --> 00:12:33,090 for another one. They decide, well, maybe a lot of the costs come from the actual incubation. 140 00:12:33,090 --> 00:12:38,430 That's after all, it's quite costly for the bird. So they like this one. They didn't get free eggs. They actually 141 00:12:38,430 --> 00:12:43,590 got free chicks. So they waited for the eggs to actually hatch and then transfer to 142 00:12:43,590 --> 00:12:48,840 newborn chicks. I'm going to sort of put them on the side there. So she's also going to have two extra, 143 00:12:48,840 --> 00:12:53,910 but she got them as chicks rather than as eggs. And then finally, this one is going 144 00:12:53,910 --> 00:12:59,070 to have the toughest treatment. So what they actually did was to remove some eggs from 145 00:12:59,070 --> 00:13:04,770 the nest. And if you remove eggs from a great titmice, they will lay more. 146 00:13:04,770 --> 00:13:11,160 So she lays a couple of extra eggs and then we put these ones back. 147 00:13:11,160 --> 00:13:16,500 Right. And now this one has the same class size as this one or 148 00:13:16,500 --> 00:13:21,510 would have done in my cabinet rolled off. I just try and replace it. All right. So she's got the same as that 149 00:13:21,510 --> 00:13:26,940 one. But those ones came for free. And this one had to pay the full cost 150 00:13:26,940 --> 00:13:32,700 of those eggs because she had to actually leave them. And when they then calculated 151 00:13:32,700 --> 00:13:38,130 the number of surviving offspring, how well all these birds did. These ones definitely 152 00:13:38,130 --> 00:13:43,500 had lower fitness. That means that if you if they're really forced to pay the full 153 00:13:43,500 --> 00:13:49,080 cost of all of those extra eggs, then it really does have fitness consequences. 154 00:13:49,080 --> 00:13:54,240 And those fitness consequences came in part because the females didn't survive as well 155 00:13:54,240 --> 00:13:59,820 till the following year. But also in part because if you give great, it's extra chicks, 156 00:13:59,820 --> 00:14:05,070 they don't actually survive as well, because the larger the breed size, the smaller the chicks 157 00:14:05,070 --> 00:14:10,350 are. So it looks like they've got more chicks, but actually they don't actually survive quite 158 00:14:10,350 --> 00:14:15,450 as well. So some pretty clever stuff. It's all done very carefully by trained 159 00:14:15,450 --> 00:14:20,610 researchers who know how to handle the birds and the eggs and know how much stress the birds 160 00:14:20,610 --> 00:14:25,620 can manage. Don't try anything like this at home, for goodness sake. Right. Well, 161 00:14:25,620 --> 00:14:30,930 let's end this where we began at the back of the garden, looking at my empty nest, 162 00:14:30,930 --> 00:14:36,000 empty nest box anyway. So my blue [INAUDIBLE] have gone off and I hope that 163 00:14:36,000 --> 00:14:41,010 those young are still alive out there and being fed by their parents. I hope this doesn't 164 00:14:41,010 --> 00:14:46,050 happen to them. This was footage taken by my uncle. A sparrow hawk arrived in 165 00:14:46,050 --> 00:14:51,090 his garden just literally a few days ago, found the Black Bird's Nest and came back 166 00:14:51,090 --> 00:14:56,130 and at one blackbird nestling after another. I'm afraid that is what Raptors do once they find the 167 00:14:56,130 --> 00:15:01,140 nest. They're not going to leave any of them behind. However, we can at least say that the 168 00:15:01,140 --> 00:15:06,240 Sparrowhawk is a natural predator and it does have its own chicks to feed. I would plead with 169 00:15:06,240 --> 00:15:11,250 you if you have a cat to think about the damage that cats cause. They are the source 170 00:15:11,250 --> 00:15:16,970 of water. The biggest source of mortality for a lot of blue and greater chicks in gardens. 171 00:15:16,970 --> 00:15:22,200 And of course, people want to keep cats and they are lovely animals. But there are things you can do to limit the damage they cause, 172 00:15:22,200 --> 00:15:27,320 like making sure that they have a bell and also actually not letting them wander around at night 173 00:15:27,320 --> 00:15:32,460 where upset. That's not when they tend to eat looters. But they do cause a lot of damage to frogs and small mammals at that 174 00:15:32,460 --> 00:15:37,470 time. Well, I hope in your garden this week, you can maybe see some of these newly 175 00:15:37,470 --> 00:15:42,900 fledged blue turtles and great chicks feeding and and moving around the garden and finding 176 00:15:42,900 --> 00:16:19,280 food for themselves. And we'll see you next time on that garbology.