[Applause] [Music] hey [Music] little slavers in 1981 dr alberto described a new species of ant in the southern spanish mountain range of sierra nevada russell mirmax minoukai this species belongs to a very rare group of ants with only another three known species at that time all of them found in the asian steps the spanish species is found in the high mountains although in reality its habitat is quite similar to that of its asian cousins one of the aspects of this new app that particularly drew the researchers attention was the way it traveled from place to
place after leaving the nest a worker would wander erratically making frequent stops each time it stopped the ant would turn around 360 degrees and then continue on his way by contrast when he returned to the anthill he took the shortest and straightest route the explanation for this way of getting around is that instead of leaving a chemical trail like most stands rosomeumeks orient themselves by the sun this method is an adaptation to life in arid and sunny climes they're active during the hours of maximum sunlight when chemical trails called pheromone trails evaporate quickly another ant
species that also works during the time of maximum sunlight is proformica and the relationship between the two species is truly spectacular when a rosso miramax finds a performing a nest he runs back to his own nest [Music] there he alerts several of his colleagues next he grabs one of them with his mandibles and carries him off heading straight for the performiga nest [Music] once his companion has seen the route they both go back to the anthill and carry off two more of their colleagues in their mandibles this operation is repeated many times as more and
more ads show the way in turn to other ads when some 50 or 60 workers have gathered at the proformica nest they become very agitated and assault the nest then they spend the next 24 hours in apparent tranquility outside the following day around noon they organize a return trip to the nest to get slaves and the booty setting up a transport chain burying larvae pupae and cut abdomens full of sugar this process can last two days when the adult proformica emerge in the nest of their captors they begin to work for them as if it
were their own anthill the rosomir mechs on the other hand spend all their time organizing new attacks to capture new slaves lucky for the proformica the rosamir mex is a relatively rare species but why don't the proformica defend themselves more effectively against the slavers the researchers have discovered something that adds even greater emotion to the relation between the two species if the proformica defend themselves by attacking the russomir megs then the latter behave very violently and usually kill the whole ant hill on the other hand if the proformica offer little resistance to the slavers there
is a good chance around 40 that at least part of the ant hill will be spared this behavior on the part of the enslaving ads which we might describe as acting like a mafia is what really maintains the current balance between the slaves and their captors do [Music] color codes to the human eye beautifully colored bird's feathers are a real delight to contemplate we humans use clothes to communicate visual information relating to what's inside well in the same way birds use the color of their feathers to communicate important attributes and like an expensive wedding outfit
these breathtaking colors are expensive to produce and costly to maintain yellows oranges and reds are all composed of carotenes substances that birds can't synthesize on their own and have to obtain in their diet only those birds that are able to find and eat certain seeds fruits and leaves are able to display these amazing colors others make do by hunting for caterpillars and insects that feed on key carotene-rich plants parasites and diseases also affect colors for example because birds have to redirect resources from other physiological functions to the immune system so displaying brilliant colors also sends
out the message that the animal has the ability to acquire splendor and maintain it on the other hand black is made from melanin and those who have the biggest black patches are the most aggressive and hold the highest status in the social hierarchy these individuals also defend themselves and their offspring against predators with more ferocity so in the same animal different colors can indicate different qualities but how did we arrive at these conclusions dr juan carlos and his team have been investigating these very issues at the natural science museum of barcelona for over 20 years
using a spectrophotometer in their laboratory they were able to measure the intensity and tone of the colours of feathers previously collected from great tits [Music] evidence from blood tests revealed that the yellowest individuals were in the best physical condition great tits often nest in wooden bird houses and like most birds they defend their young ferociously from possible predators daring even to challenge people by capturing the males and measuring the black patch on their breasts dr sinar's team was able to confirm that the males with the largest black patches were the ones who defended with the
greatest intensity siskins also have black markings to see if a black marking in itself indicated aggressiveness dr cenar used a felt tip marker to increase the size of the bib on male siskins their peers immediately became more afraid of them and the bigger bibb siskins became more dominant in the group the yellow on the siskin's wing is formed of carotenoids and as with the great tit it demonstrates the individual skill in finding food interestingly the ability to find food isn't necessarily related to social dominance yellow and black indicate different qualities so now the question is
which quantity is more important to females when choosing a mate in order to study the preferences of female siskins the team used computerized cages with automatic detection devices inside the cages the female siskins were able to choose between two males with different colors and qualities the results were clear the females preferred the males with yellower wings and weren't going to be seduced by the dominance indicated by the black bib by studying their coloring the females really were gathering reliable information about their potential partner as we've seen a fancy outfit can end up being very costly
to birds too but it serves the most important purpose of all to keep their genes flowing through the story of life [Music] the paradox of blue eggs the color of bird's eggs has traditionally been seen as a way to hide the eggs from predators nonetheless almost half of all bird species lay eggs with blue or green tones which doesn't seem to support the theory dr juan moreno of spain's national museum of natural sciences maintains that through egg color the females communicate vital information to their partners it could be something similar to the eye-catching plumage that
male birds display as a sign of their top physical condition if that's what these colors do however why don't the females wear them in their own plumage the females tend to spend a lot of time in their nests incubating the eggs or keeping the chips warm and protecting them if they were brightly coloured the females would be easily spotted by predators so how should they indicate their quality as a mate one solution might be to lay colored eggs for a signal to be believable however it must guarantee that it does really reflect the quality of
the animal that emits it if any random female could lay eggs with an equally intense color then that color would be useless for the purposes of communication a pigment known as biliverden is responsible for the presence of green and blue colors in eggshells biliverdin is made from hemoglobin which is found in the blood and the pigment has high antioxidant powers by depositing biliverdin in the eggshell the female indicates that she has been able to do without a certain quantity of antioxidants that's a luxury only genuinely healthy females can afford but unlike the colored feathers that
help males to find mates females only display colors in their eggs when they already have a mate and they've begun to breed what's the point of those colors at this late stage what does this signal tell the male dr juan moreno used nest boxes to study the behavior of male pine flycatchers in relation to the color of the eggs of their respective mates measured the intensity of the color of eggs using a spectrophotometer on the same day they were hatched then he proved that the males of the nests with the bluest eggs brought back a
greater quantity of food so in addition the chicks from these nests attained better physical condition could the blue color of the eggs really be what motivated the male to work harder in order to verify this dr moreno conducted an experiment that involved introducing an artificially bright blue egg to some of the clutches the effect was clear the males worked harder gathering a greater quantity of food throughout the reproductive period and the chicks in these nests reached higher than average body weights signals by means of external structures is a fascinating area of research that warrants further
investigation and promises very interesting results [Music] so [Music] [Applause] [Music] perfumed don juans [Music] the males of many species of lizards sport eye-catching colors you might think that as these reptiles evolve they develop this bright display to better attract a mate nevertheless in many cases the females don't seem to show much interest in the male's colors rather these colors appear to be more a sign of dominance aimed at other males [Music] so it seems that the females could be at the mercy of these dominant males as regards the search for a mate or maybe not
dr pillar lopeth and dr jose martin of spain's national museum of natural sciences work in the guadarama mountains outside madrid with a small species of lizard that lives in the high mountains of central spain the males of the carpeting rock lizard are green while the females are brownish-grey [Music] the males mark their territory by depositing excrement on top of rocks just as many mammals do the females approach and smell these excrements and get very precise information about the males these observations led the researchers to hypothesize for the first time that chemical signals could play an
important role when this species chooses a mate to study this question first you have to capture some of the animals the way they are captured is quite striking using a rod and a soft noose the researchers fish the little lizards at an altitude of almost 2000 metres above sea level [Music] the males display lines of glands on their legs that are called femoral pores these pores secrete a waxy substance that the researchers carefully collected because it contains important chemical signals [Music] each male was weighed and measured to collect its biometric data in addition its immune
system was evaluated using a test similar to allergy tests in humans in a field experiment the scientists smeared some rocks with the scent extracted from different males and observed that the females chose those rocks that smelled like the males that were in the best physical condition in the laboratory the females also indicated by sniffing more times with their tongues that they preferred the sense of certain males the researchers observed that the most attractive sense belonged precisely to the best physical specimens with the best immune systems beyond that the samples were analyzed with a spectrometer which
revealed that the male's perfume contained vitamins and other essential chemical compounds that are hard to get the males secrete antioxidant substances which are very important for their health and which they have to obtain every day through what they eat the amount secreted depends on the male's physical state the healthiest strongest and most skilled are able to secrete the most expensive perfume shall we say and so they are more attractive to females so it is a sincere and honest chemical signal with no trickery that lets the females choose the fathers with the best genes for their
future children appearances are sometimes misleading but our smell always gives us away [Music] calling cards in mountainous areas the erosion caused by ice has modeled landscapes of loose stones called scree at first glance they look barren of life but actually they are home to some fascinating flora and fauna when the temperature grows mild some agile and amusing rodents scamper over these granitic rocks these are european snow voles which live in the main mountain chains on the eurasian continent always at altitudes of more than one thousand meters snowfalls are specially adapted to live among the rocks
to that end they have a longer tail than other voles and long thick tactile hairs called vibrissa on their snouts [Music] the males as is the case with most mammals are territorial and mark their territories with urine surprisingly their territories overlap which leads to frequent encounters that curiously usually aren't aggressive so why bother to mark their territory dr juan jose luke and dr pilar lopez are working to discover just what kind of messages these smelly marks may contain they have confirmed that when an intruder runs into the vole who marked the territory he recognizes the
owner and the encounter is much less violent than when two males bump into each other and neither has marked the territory so the centered signals serve both as a calling card and as a way for any male to know just who is the true owner of the territory which makes each vol's position clear and reduces the fighting among them but the snow vole's chemical signals also play a sexual role the researchers have confirmed this with an experiment involving the selection of a mate they designed a y-shaped room and they placed a sample of a different
male in each branch they placed a group of females at the other end and observed their behavior they didn't seem to have many doubts when they reached the crossroads most of the females chose the smell of certain males but the most interesting thing is that the sense they preferred corresponded to males with specific characteristics for example their body shapes were more symmetrical as was proven by taking a series of biometric measurements what's more blood tests revealed that the preferred males were healthier and in better physical shape among snowballs it seems essential to introduce yourself unambiguously
to your rivals and prospective mates their calling cards are truly full of all kinds of details about the owners in this case [Music] um [Music] fertilization on a card [Music] each year male red deer vigorously compete for the females [Music] in southern spain the period of sexual activity called the rut takes place in september after the dry hot summer most of the vegetation is dry and the hinds have to seek out the few areas where there is still something green to eat in donano national park there is a strip of land along the marshes of
the guadalcave river where the water table is close to the surface and some fields stay green all year round the hinds come here to feed during this season of general scarcity taking advantage of this situation some males take possession of strategically placed territories that assure them the chance to make contact with the females [Music] when they become territorial the stags stay put in their domains and have to wait for their prospective mates to approach them the master of the herald isn't able to control his concubines when they decide to change one hero for another [Music]
dr juan carranza and his team used plastic tape to fence off some of these territories these tapes forced the resigned males to move elsewhere for a few days when they had to leave the areas with the best pastures their females abandoned them so it seems that the hinds weren't so much interested in the stags as in the food there are other forces which drive the hinds to join the harem the young males hound them continually when they're alone making them run so when they find a harem defended by an adult male they stay there where
they can enjoy his protection and a little tranquility or perhaps just so they can keep eating but what happens at the moment of truth that is when one of those stags is going to father a calf modern genetic techniques have revealed that the hinds don't mate with just any pseudo [Music] when they analyzed the calves genetically they discovered something surprising the heinz had been fertilized by stags with different characteristics according to the gender of the calf they were going to give birth to [Music] those hinds that had a female offspring had mated with stags that
were genetically very different from them and yet those hinds that had a male calf had mated with large and powerful stags that nonetheless weren't all that different from them genetically [Music] for a male calf it is essential that he inherits some of his father's qualities that will let him stand out from his rivals that's the only way he'll be able to compete successfully when the time comes on the other hand for female parents which won't have to fight size and strength aren't so important for them the best genetic gift their mother can give them is
the vigor of a hybrid the result of mating with a genetically distinct father good peaceful places to eat may be a goal in themselves but they also represent a good way to provoke rivals between males and showcase their qualities circumstances that the females take advantage of to take control of the situation and get the best genes for their offspring [Music] [Applause] [Music] the kiss of death [Music] reproduction can have dramatic consequences in the world of spiders especially for males who often sacrifice their lives whilst trying to mate with a female but this tragic ending doesn't
always unfold what factors compel spiders to resort to cannibalism why is this apparently cruel act persisted in the course of evolution [Music] dr jordy studies lycosa tarantula a large wolf spider species found in the southeastern spanish province of almeria and carries out field experiments in an attempt to unravel the secrets of their behavior males can be distinguished from females by the swelling of the tips of the pedipalps which serve as copulatory organs a group of females was given extra food and then they were observed during mating these females were less prone to cannibalism than their
counterparts who didn't receive the artificial extra rations these shall we say hungrier females seem to make up their low weight by eating the males reaching the same weight as the females who had been artificially fed by the end of the mating period so it seems that sexual cannibalism is in reality a way to compensate for the lack of food the males represent a very important food resource for reproductive females which can achieve heavier batches of eggs with a greater number of offspring who are likewise bigger the males are not just food for the females they
are also the mates who fertilize them and so the females try to make sure they get their sperm before eating the males if an area is short of males the females won't eat them since they need the sperm the males provide [Music] but what do the males do to avoid being eaten well the females are generally nocturnal feeders and their greater aggressiveness at night forces the males to stay at a safe distance from the entrance to their mates nests at daybreak the female calms down and the males can approach them even to the point of
sharing the nest [Music] what's more not all females are equally dangerous dr moyer studied the question of which females were more successful with males he discovered that males were more attracted to smaller females who were therefore less voracious to the best-fed females and to virgins which still hadn't acquired any sperm [Music] males keep trying to mate despite the continuing risk of being eaten but they try to seek out the less dangerous females to give themselves at least a fighting chance [Music] these colored areas both on the underside of the legs and on the underside of
the abdomen or epistasoma contain information that can be used by the males to determine exactly how dangerous certain females are it's debatable whether the females really want to give away such clues to potential mates these signals are actually used to ward off other females competing for their territory the markings on their legs seem to indicate their size and indeed they have been proven to correspond to the size of the spider's body at the same time the markings on the abdomen could serve as amplifiers of their physical condition since they correspond closely to the amount of
nutrients stored in the abdomen during mating because of the posture adopted by these spiders the male always sees the underside of the female's abdomen so he could use these same markings to assess the risks he's running during mating although from a human perspective it may seem cruel the sexual cannibalism of lycosa tarantula is simply a way for the females who the males find irresistible to make the most of the situation and decide whether to use their mates as partners or as a snack [Music] a mother's courage [Music] the last eurasian brown bears on the iberian
in peninsula cantabrian mountain range they represent one of the most threatened mammal populations in the world their situation is already made difficult by living in an environment that is heavily influenced by humans with an excessively fragmented habitat the forest has disappeared in many areas replaced by pastureland the bears are forced to seek refuge in rough and inaccessible areas [Music] the researchers alberto fernandez and javier naves from the team of dr miguel de leves are studying the reproductive behavior of these bears and how it affects their conservation for the first time with this species this group
has been able to directly observe males killing cubs for sexual purposes they have even had access to graphic proof of a female fighting to defend her cubs from a male's attack filmed by charts by a park ranger and despite the poor quality of the images this video is unique in the world showing a female trying to defend her cubs from the attack of a male who eventually ends up getting them away from her the video is chilling and spectacular evidence of a behavior never before observed [Music] the female bears display what is called induced ovulation
that is they only ovulate in the presence of a male on the other hand the cubs stay with her for a year and a half during which time the females don't go into heat if a male whose greatest interest is to perpetuate his genes runs across a mother with cubs by another bear he won't be able to mate with her until her cubs become independent that's why he will try to take them away from her and kill them that way the female will go into heat after a few days and the male can inseminate her
to produce another litter but this time the cubs will be his own to avoid the male's attacks the females seek refuge in remote breeding areas nevertheless in an environment under increasing pressure from humans sometimes mothers with carbs have to leave their hiding places exposing them to possible unwanted encounters with males the researchers have analyzed the characteristics of the breeding areas and have compared them with the areas where they have observed the cub killings the latter areas show different characteristics which seems to indicate that the females that were attacked had been bothered and were outside the
areas they normally frequent this behavior on the part of the males which in natural conditions would only happen on rare occasions may be happening more frequently because of the greater fragmentation of the forest habitat and greater pressure from humans the behavior study may reveal key elements for the future of the bear populations especially when they find themselves in such extreme conditions the brown bear is a true treasure of the iberian fauna and knowledge of its behavior is providing us with the necessary tools to design more effective conservations conflictive parenting during the summer months the rivers
and streams are full of damselflies these insects like many others are drawn to watercourses when it's time to reproduce they lay their eggs in the water where they live the first phase of their lives [Applause] [Music] the females are very demanding when choosing where to lay their eggs and males know it they scout out the area and establish themselves in a territory where they wait to mate with the females that approach them when the number of damselflies is moderate reproduction takes place in apparent [Music] harmony when they couple the male holds the female by the
neck as she arches her abdomen to receive the male sperm [Music] after they populate the males defend the females while they lay their eggs [Applause] trouble arises when the density of the depth of flies is elevated the females don't need to copulate more than once since they are able to store the sperm the males on the other hand try to mate with every female they meet the more females they manage to fertilize the greater the number of descendants they will leave behind the females end up being hounded to such an extent that they are even
prevented from laying their eggs dr adolfo cordero of the university of vigo is studying the damselflies of the collopteryx genus and their complicated sexual behavior to be able to distinguish them from one another he paints numbers on their wings field observations have shown that females subjected to such relentless pursuit accept the couplings instead of trying to avoid them since the copulation is very quick accepting it may be better than resisting besides this way the male will defend her from the hassling of others some females pretend to be the mates of territorial males hiding and trying
to supplant the real mate so that they can get his protection without having to mate again apparently the males aren't able to distinguish their mates from the females that sneak into their territory in this context of multiple copulations the males and females develop sophisticated strategies to optimize their reproduction since the females copulate with more than one male and so store the sperm of more than one male the males end up competing inside the female to ensure they have descendants when the males mate with the females they remove some of their competitors sperm before putting in
their own to do that their penis has evolved into a sort of hook but even if the male has managed to insert his sperm in the female he still has no guarantee of success if she doesn't want to females have sometimes been observed expelling a little drop of sperm following copulation [Music] dr cordero uses a portable insectarium to manually mate pairs of damselflies [Music] with this experiment he's trying to discover if the females expel the sperm of unwanted males [Music] using dark cardboard he has confirmed that they are able to expel semen even when flying
[Music] the nuptial dance of the damselflies is spectacular no doubt but the battles that take place inside the female can be even more so [Music] a fortunate forgetfulness [Music] every autumn in mediterranean forests the whole oaks produce a rich harvest their large and nutritious acorns are a real blessing for the arrival of winter a resource that animals of all sizes take advantage of [Music] after sundown it's the turn of the greatest specialists the rodents among which the algerian mouse stands out [Music] as many as 9 out of every 10 acorns may end up in his
pores but this job has its risks predators like the common genet also take advantage of this time to visit the homeless in search of prey [Music] danger also arrives by air as various nocturnal birds of prey like the owl feed basically on rodents [Music] dr mario diaz team is researching this complex series of interactions and the consequences for the whole modes the researchers place cameras that take pictures when an electric eye sets them off with this method they have confirmed that the rodents adapt their behavior when predators are present the mice reduce the risk by
working in the hours in the middle of the night when predators are less active using acorns marked with thread and a label the researchers have discovered that they eat the smallest acorns right there and carry off and hide the largest ones skillfully choosing the acorns that haven't been attacked by insects [Music] the mice pick areas of dense undergrowth when there are lots of red deer and wild boar around thus avoiding the deer's hooves and the boar's snouts [Music] the safest spots are in big demand and some come not to put up food but to sack
the pantries of others this forces them to look for many different hiding places even in the open fields but a rodent's memory isn't infallible a small percentage of the buried acorns are never recovered and curiously this is the tree's big chance to reproduce the acorns that fall at the foot of the trees are consumed by many animals without a chance to germinate and take root in addition new home oaks need the shade and protection of the thickets to complete successfully the most critical phase in their development if too many enemies prevent the rodents from doing
their job it can be very difficult for the tree to reproduce because the acorns aren't taken to their hiding places but in the opposite situation if the mice don't feel any pressure from predators or competitors they consume the acorns at the foot of the tree with no need to bury them in protected places only when the presence of predators and competitors is moderate and unpredictable do the mice forget some of the acorns becoming the home oak's best ally and thus encouraging the regeneration of the mediterranean forests [Music] breeding helpers in the southwest of the iberian
peninsula lives a bird that is only found here and in eastern asia the azure winged magpie the most likely explanation is that the glacial ages of the last 500 000 years have managed to drive the bird to extinction in most of the eurasian continent leaving it only at the two extremes of its original distribution azure winged magpies are very social birds they live in flocks where they establish complex relationships not only among families but also in something like the gangs of friends among humans [Music] when the time comes to reproduce they do so in colonies
both the male and the female care for and feed their chicks when they approach the nest they alert the chicks so they'll ask for food they say something like who wants some only then did you shout gimme if any predators are near the parent silence ensures that no chick will betray himself by asking before it's time to but when azure winged magpies are busy carrying out the task of feeding their chicks something even more surprising happens other individuals different from the breeding pair also bring food to the nest and help defend it from predators the
helpers are usually males both young ones and adults some of them help out from the start of the reproductive season without breeding themselves others do it when they've lost their own clutch of eggs for some reason sometimes several helpers join forces to aid the same breeding pair contributing in a big way to easing the exhausting task of raising the chicks although not all breeding parents are so lucky as to have helpers dr carlos de la cruz and dr juliana valencia are studying azure winged magpie behavior in a breeding colony in badahorth [Music] here most of
the individuals are marked and have been followed for several years [Music] the researchers have confirmed that the presence of helpers brings really big benefits to the nest the chicks and nests with helpers receive more food grow better and have a better chance to survive they even have a stronger immune system you might expect that this help is a relief for the parents who could save their energy nevertheless the researchers observed that contrary to what they expected the parents that are backed by this team of collaborators work harder than the ones that don't have helpers especially
the male which can increase the food he brings to the nest by as much as 20 percent when there are helpers in the nest why work harder when you've got help the reason is that the presence of helpers makes the clutch more valuable the number of nests lost to predators is very high up to 80 percent when there are no helpers while the helpers can help reduce the number of nests lost the increased value of the clutch means the investment is safer which encourages the parents to work harder for thousands of years natural selection has
favored those individuals that have known how to get maximum results from their efforts in the form of young for the following generations investment and profitability are economic terms but they describe perfectly the way in which animals measure out their efforts according to their chances of success success which in nature means nothing other than descendants who can transmit your genetic material down through time [Music] you
