i'm fresher than a dog be against the law i'm living my life like the rules of the game and this is "nightline." >> tonight news from the showdown in nevada. it's the first contestor the republican presidential hopefuls. and abc news is projecting that donald trump will finish first in the state's caucuses. down his campaign? and we go into the wild to the front lines of a modern war to save an ancient animal from extinction. we're with the rangers their lives to track poex here's kill for the coveted rhino s.

led to their daughter's murder. in this world of anonymous prichtparents have no idea what their kids are doing online. >> i wish i would have been there for my daughter. >> these students take usvate world.

evening. breaking news as we come on the air. abc news can now project donald trump will be the winner in the nevada republican caucuses. analysis, it is a two-person race for second between marco rubio and ted cruz. a win for trump will make three victories in a row after took first prize in surl south carolina and new hampshire. people said they were in favor of the outsider and of those voters, 70% said they billionaire businessman. we now turn to a high stakes war against trafficking. world more than gold, cocaine, even diamonds. the coveted hornrhino. but now a new military grade piece of machinery is being

ruthless poachers. to the south african bush. >> in the pitch black of the south african bush, these rangers can only listen and smell for any sign that'ss near. >> if they're not quiet, they will pick you up first. >> they hunt forery night. >> we need to protect them from being shot. >> tonight our patrol has eyes in the sky. we're on the front lines of a modern er an ancient animal. the future of the rhino is in the balance. according to the world wildlife fun, in south africa alone,g has skyrocketed 9,000% in just 8 years, fueled by a growing demand for its horn. ground up and used as a in asia. more expensive than gold and some say more desirable than cocaine. with the millions made from the illegal trade, now ma controlled by criminal networks, the plight of

implications. in the oldest south africa, they're trying something new. this is command central for air shepherd. a pilot project where ft are being deployed to help park rangers in their fight. >> nighttime operations has always been very, very difficult for thesed besides meeting one the poachers you might be tracking, the danger to the animals. >> we'll just guys carry on. we'll just keep you in the frame. >> tonight's mission is about to begin and tensions are high. with ruthless poexers dark, and the reason news of

a lion. don't let the laughter fool you. my nerves are kicking don't know what's on the other side of the bush. the drone infraredup heat signatures of animals and humans. and sends images back real-time to the commandhite dots are us on patrol. the experienced rangers keep several feet between them so if one of them is don't all go down at once. >> how many does it help? give you a sense of ease to some degree hovering above you now? >> i think it is quite fortunate

>> no signs ofis patrol. but in this vast territory, the drones and patrols can only . in the few days we're here, four rhinos were killed. many of the rinl owes that survive these attacks are brought sanctuary. >> high, big fello. somebody messed you up. somebody got paid off you, big e this mother and her calf. >> we hear poaching all the time. look at this animal. first time i'm seeing it in my life up close and but just, i mean, until you're this close to it. that is brutal. >> three months ago her in the bush, still groggy. her horn hacked off. left for dead. her baby clinging to her side. >> is the animal still in no. >> as much as we can get a success.

the two will be released back into the reserve. >> man it's a shame this place is even necessary. >> it is almost unfathomable to think, what would drive someone to this kind of brutality, until a single rhino horn can fetch up to a quarter million dollars on the black market. even a small fraction of that is hard to resist in a place with >> we're in a township outside pretoria. our poacher set up a meeting for us. >> a former poacher has agreed to meet us. only if we don't show his face. >> did you ever feel badou were doing for killing these animals? >> through a he felt bad but needed money to feed his family.

killed at least 50 rhinos.w always had a guy on the inside. a ranger on the take. >> park officials are being paid off. police are being paid off. the level of corruptions into local government offices. given the amounts of money, anyone is open to being corrupted. >>e money is taken by criminal networks. most of it ends up here in vietnam. >> it is a status symbol for the it up in special designed dishes. mix it with rice wine and water. >> it is that said toerything. despite the ban on the trading of rhino horn, markets can still be found as seen in this bbc program. here the back of a tailor l is underway.

>> but it's a >> there is no scientific proof that rhino horn has any benefit. >> i want to point out that it is simply made of xactly the same as your finger nails. >> celebrities. >> ask your friends and family never to buy rhino horn.nce william took up the cause. >> together we can save our wild rhinos. when the buying stops, the killing can too. >> may only go so far. >> you're dealing with faith. people firmly believe that rhino horn does have the attributes that it is said to have. as telling a christian, jesus christ doesn't exist. that's the level of belief that you're dealing with. for many people, it crosses

>> in africa the focus is on steming the supply. to harvesting the horns and selling them lega you know, the rhino horn grows back. it is a painless, relatively uninvasive procedure. >> i'm telling way we will save the rhinos from extinction. >> while not everyone agrees on the best path forward, what we've seen here on the fronteople trying everything. that's probably what it will do and more to win this battle against extinction. south africa. when we come back, the secret world of teens on social media. the digital dangers even the most tech savvy parents might not know about. that's where your friends are. seriously, it's, it's really fine. you don't want to be seen with your dad? no, it's..no.. oh, there's tracy.onking ] [ forward collision warning ]

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een easy. it seal in the digital age, we have more blind spots to worry about. tonight, yahoo! global news anchor katie courick at a tragedy and gives as you glimpse at the world of teens and social media. >> nicole was a veryon. >> tammy weeks was facing the unimaginable unimaginable. her 13-year-oldead. >> she touched many people. >> a 13-year-old girl making headlines. >> the search for answers is just beginning. >> the reaction to hers become part of a conversation about girls and social media. nicole had secretly been

tech student. 18-year-old david on the social media app kick. according to investigators, they say that one night last month, nicole snuck out of her parents' house the meet up with never returned home. she was missing for three days until her body was discovered 80 miles away. >> a very preliminary of the cause of death is stabbing. >> nicole's story has become a cautionary tale about the dangers of secret messaging apps and their anonymous 'm willing to say kick is the devil for young children. it is like a free ability to text and parents can't see the number going in and out. >> an alleged female accomplice are now accused of kidnapping and murder of nicole. neither has entered a plea. nicole's father and stepith 2020. >> i wish you could have been there for my daughter. she deserved me to be there and

>> nicole'ss she turned to social media for acceptance after she was severely bullied in school. >> she had a huge boy crush kind of thing.s kind of innocent. she was still a child. and all she wanted was just the attention. >> we reached out to the people who run kik and they toldhave zero tolerance for any behavior that potentially affects safety of our users. we offer blocking and reporting tools to allow users to flagnted content. we are reviewing all aspects. >> when this case surfaced, have you heard of kik?very girl that i interviewed. >> but those secret apps are just part of the story. nancy has been reportiulture for more than a decade. in her new book, american girls, social media and the secret

she explores the dangers of coming of age by social media. >> tell me about the role this is playing in the life of the average teenage girl. >> conversations i had with some girls in los angeles really set the tone for the whole book. she said social media is destroying our lives.on't you go off it? she said then i would have no life. >> she said what she discovered was troubling. negative self-esteem. sometimes harsh judgment and has experienced. >> i got a message on instagram from this guy. he seems like he was my age so i trust him. friends. i started talking to him and we got really close. >> the friendship took a turn and carey stop communicating.

one of his friends began writing hurtful things. >> they were saying you're ugly and cursing me out when they've never met me or know me at all. it really scared me. >> her mom decided to do something about it.d out that the person who was actually cyber bullying her was not the boy but a friend of his who he was and she had sort of taken on this crusade to get back at my daughter for no reason. i spoke to this woman. is cyber bullying my child. and so she promised me it would never happen again. that she would talk to this kid'sd thankfully that did put an end to it. >> how has social media krebed to the notion of cyber almost every girl has been cyber bullied.

that because it didn't lead to >> sale says social media has become a popularity contest. where teens seek validation from the pictures they post and the number of like they it is having a major impact on how teenage girls view themselves. 18-year-old olivia agrees. >> i got over 150 oh, you know, what a good picture i took. and then if you post a photo that you think is good as well and you don't get a the love god. should i take this down? >> she said she met some girls who spend hours taking pictures of themselves ande images. we asked olivia to show us how some of these apps work. >> i can whiten my ter smile. if i wanted to be super blond.

i can make my arm at some people don't realize is that, look at the door. it's not supposed to look like that. >> but she says she these apps sparingly. >> sometimes if my voice gets really oily, i'll do that. but i don't reshape my about this depression we're hearing about among teenagers? >> think about it. if what you are thinking about is do i look hot? am i going tohis photo? these the constant thoughts being raised in teenage girls' minds through their use of social media. it is nots not something that produces a feeling of well being or security. >> both olivia and carey's moms say talking to about social media behavior is critically important. >> basically, your tarnlg wants

>> this is the way the kids will is way life is. and you need to have the channels of communication open. you need to educate them asssible. as to what the dangers are. >> for "nightline," katie couric in los nancy's book, american girls is on sale now. up next, a look ahead to a special event on profoundly topic. consent on campus. lease a 2016 lincoln mkx

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sexual assault and the of alcohol and hook-up culture creating what are some are calling fault lines. we hear from those whose us a lot to think about. >> if anyone had ever asked me, if someone has sex with you and you don't want them to have sex top them from doing that? the answer would have 110% been yes. then when the situation actually arose, thaponse to it. >> "nightline" invited experts and advocates to punish state university. some who see an epidemic of others who feel the pendulum has swung too far accusing men. we examine consent and a vital piece of sex education that's been missing.

a "nightline" event. watching abc news. overnight with breaking news and tune into "good morning america." and as always, we're online at

d, almost comics unleashed. with your host, byron allen. tonight byron welcomes todd west. keith. shawn collins. and maria lampert. now a man who invested all of his money incker stores, byron allen! [ cheers and applause ] [ cheers and applause ]