Análisis energético: Preferencia conformacional

Chapter%3:

%Movement%patterns%and%habitat%use%-

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3.1

Introduction.

Given!the!recent!global!declines!in!amphibian!abundance!and!distribution,!it!has!become!

increasingly!important!to!protect!threatened!species!and!populations;!however,!due!to!the!

high!diversity!of!life!strategies!and!complex!life!cycles,!defining!effective!protection!areas!is!

challenging.!It!is!widely!understood!that!protection!of!amphibian!species!should!consider!

all! life! stages! and! therefore! should! include! all! types! of! habitat! used! (i.e.! aquatic! and!

terrestrial,! Wells! 2010).! For! streamWbreeding! amphibians,! many! studies! have! highlighted!

the! importance! of! terrestrial! habitat! adjacent! to! streams,! and! have! called! for! the!

protection!of!buffer!zones!(deMaynadier!and!Hunter!Jr!1995,!Vesely!and!McComb!2002,!

Semlitsch! and! Bodie! 2003).! However,! not! all! streamWbreeding! species! have! similar!

terrestrial! needs! (Semlitsch! and! Bodie! 2003).! For! example,! some! streamWbreeding!

amphibians! only! move! less! than! ten! metres! away! from! streams,! while! others,! move!

hundreds!of!metres!away!(Crawford!and!Semlitsch!2007).!Therefore,!to!protect!individual!

species,!it!is!essential!to!know!what!types!of!habitats!are!used!and!when!each!habitat!is!

used.!!

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3.1.1

Amphibian%migrations%and%movements%

home!ranges!during!the!postWbreeding!season!are!common!(Wells!2010).!Within!terrestrial!

habitat,!amphibians!often!move!through!the!landscape!to!find!shelter!and!food.!Whereas!

some!species!are!highly!vagile,!most!only!move!short!distances!(Wells!2010).!In!addition!to!

daily! movement! patterns! and! seasonal! migrations,! longer! dispersal! movements! between!

breeding! sites! are! also! common! in! amphibians.! Daily,! seasonal,! and! dispersal! movement!

patterns! are! all! important! for! population! regulation,! metapopulation! dynamics! and! the!

longWterm! persistence! of! species! (Semlitsch! 2008).! It! is! therefore! essential! for! the!

development!of!effective!management!measures!that!the!movement!patterns!and!habitat!

use!of!a!species!are!understood.!

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3.1.2

Telmatobufo-bullocki-

Telmatobufo+ bullocki+(Schmidt! 1952)+is! a! rare! and! critically! endangered! streamWbreeding!

amphibian.!They!reproduce!in!fast!flowing!mountain!streams!in!Chile's!temperate!forests,!

in!the!coastal!Nahuelbuta!mountain!range!(Formas!1988).!Habitat!loss!and!fragmentation!

have!been!identified!as!main!threats!for!T.+bullocki,!and!there!is!an!urgent!need!to!protect!

this! species'! habitat! (Veloso! et! al.! 2008,! Fenolio! et! al.! 2013).! Despite! being! historically!

observed! inside! protected! areas,! there! are! no! recent! records! of! the! species! inside!

Nahuelbuta! National! Park,! despite! several! surveys.! Furthermore,! most! of! the! known!

populations! are! in! areas! currently! covered! by! exotic! plantations,! which! poses! a! serious!

threat!to!the!species!(Chapter!2).!However,!since!little!is!known!about!this!species’!ecology!

and!behaviour,!management!and!conservation!measures!are!difficult!to!assess.!!

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found!under!a!log!150!m!from!a!stream!(Péfaur!1971).!Moreover,!the!stomach!contents!of!

the! paratype! included! terrestrial! invertebrates,! suggesting! terrestrial! feeding! (Schmidt!

1952).! Although! the! reproductive! habits! and! adaptations! of! the! species! suggest! a! strong!

relationship!with!stream!and!riparian!habitat,!the!observations!also!suggest!T.+bullocki!use!

terrestrial! habitat.! However,! the! extent! of! the! species'! terrestrial! habitat! use! remains!

unclear.!In!this!chapter,!T.+bullocki!habitat!use!was!described!through!the!use!of!tracking!

techniques!and!surveys!in!both!terrestrial!and!aquatic!habitat.!The!main!questions!behind!

this!study!were:!If!we!want!to!protect!T.+bullocki,!what!habitats!should!we!protect?!What!

constitutes! essential! habitat?! The! results! were! used! to! assess! potential! threats! and!

develop! management! recommendations! that! could! help! effectively! protect! this!

endangered!species,!including!the!estimation!of!terrestrial!core!habitat.!!

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3.2

Methods.

3.2.1

Movement%patterns%and%terrestrial%habitat%use%

Study%area%

The! location! for! the! movement! and! terrestrial! habitat! use! study,! El! Natri,! is! located! in! a!

section! of! Provoque! Stream! (2! km! length),! near! the! rural! locality! of! San! Ernesto,! in! the!

Elicura! Valley,! Biobío! Region! (37°54’! S,! 73°13’! W,! elevation! 100! m).! This! section! of! the!

stream!is!of!third!order!(sensu!Strahler

),!with!an!average!width!and!depth!of!6!m!and!40!

cm!respectively.!The!streambed!is!rocky,!with!boulders,!cobbles,!and!small!sand!banks.!The!

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!In!Strahler!stream!ordering,!the!smallest!tributaries!are!firstWorder,!and!usually!don’t!have!other! streams! feeding! them.! When! two! firstWorder! streams! join,! then! the! stream! becomes! a! secondW order! stream.! Similarly,! when! two! secondWorder! streams! join,! the! stream! becomes! a! thirdWorder!

channel! flow! is! moderate! to! fast,! with! many! riffles! and! pool! sequences,! with! a! mean!

gradient! of! 3%.! The! valley! slopes! surrounding! the! stream! are! steep! and! covered! by! a!

mosaic!of!native!forest!and!monoculture!pine!(Pinus+radiata)!plantation!(Figure!3.1).!The!

native!forest!area!is!part!of!a!fragment!of!nearly!400!ha!that!has!low!levels!of!disturbance.!

The! native! vegetation! is! characterized! by! evergreen! trees! including:! Coihue! (Nothofagus+

dombeyi),! Lingue! (Persea+ lingue),! Tiaca! (Caldcluvia+ paniculata),! Olivillo! (Aextoxicon+

punctatum),!with!a!dense!understory!dominated!by!Quila!(Chusquea+quila)!and!ferns.!This!

type! of! vegetation! provides! a! continuous! and! dense! cover.! The! pine! plantation! area! is!

mature! (24! years),! and! also! provides! a! dense! cover,! but! lacks! significant! understory.! It!

appears!the!area!was!cleared!using!fire!prior!to!plantation,!as!burnt!snags!were!frequently!

encountered.! Flat! riparian! zones! are! highly! disturbed;! they! have! been! cleared! of!

vegetation,! leaving! a! strip! of! open! area! of! approximately! 100! m! wide,! covered! by! grass!

(Figure!3.1),!with!some!patches!of!shrubs!(mainly!invasive!blackberry).!Terrestrial!habitat!

surveys! were! only! conducted! on! one! side! of! the! stream! (West),! due! to! a! collaboration!

partnership! with! the! landowners! (Forestal! Arauco),! and! because! the! East! side! had! less!

suitable!habitat!(i.e.!younger!plantation,!no!native!forest).!

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