Walter Ferrari ci guida alla scoperta della rana verde, simbolo degli stagni italiani e di un ecosistema fragile
Dalle risaie della Pianura Padana ai fossi di campagna, un viaggio tra biologia, curiosità e memorie d’infanzia per raccontare la rana per antonomasia, oggi sempre più minacciata dall’inquinamento e dalla scomparsa degli ambienti umidi
La rana per antonomasia
La rana verde o comune è la rana per antonomasia, quella che viene in mente a chiunque quando si parla di rana.
Più che di una singola specie, con rana verde si intende un complesso di specie di difficile distinzione che comprende la rana dei fossi (Pelophylax lessonae), la rana verde minore (Pelophylax esculentus) e la rana verde maggiore (Pelophylax ridibunda). È un anfibio anuro (senza coda) della famiglia Ranidae, dal muso appuntito e dalle dita ampiamente palmate.
Caratteristiche fisiche e riconoscimento
Le dimensioni vanno dai 12 ai 15 cm, con i maschi più piccoli delle femmine. Il colore del dorso varia dal verde erba al verde oliva, al verde scuro, al marrone punteggiato e spesso è presente una linea dorsale chiara; il ventre invece è bianco con macchie grigie. I maschi hanno due evidenti sacchi vocali biancastri posizionati dietro le mandibole; il loro gracidare echeggia per tutta la buona stagione.
Il corteggiamento e l’amplesso
Durante il periodo della riproduzione il maschio gonfia le guance per attirare la femmina; raggiunto dalla compagna si adagia sul suo dorso stringendola in una sorta di abbraccio, detto amplesso ascellare.
Habitat e ambienti di vita
Le rane verdi sono strettamente legate all’ambiente acquatico e sono abili nuotatrici. Si riproducono in vari habitat come risaie, marcite, fossi, stagni, bordi paludosi di laghi e fiumi. In genere evitano gli habitat freddi e ombrosi.
Ciclo annuale e svernamento
Il periodo di attività va da metà marzo a metà ottobre. D’estate vivono in acqua o nelle immediate vicinanze, mentre trascorrono l’inverno nel fango in fondo agli stagni o più raramente scavando buche nel terreno.
Riproduzione e metamorfosi
Le uova, numerosissime, vengono deposte in tarda primavera in ammassi sferici gelatinosi ancorati alla vegetazione di fondo. La metamorfosi (uova, girino, adulto) si completa in due o tre mesi.
Alimentazione
La rana verde si nutre generalmente di insetti come mosche, moscerini e zanzare e lepidotteri come farfalle e falene; i girini si nutrono di alghe e sedimento.
Predatori naturali
La rana verde è preda abituale di alcuni serpenti (bisce) e di mammiferi carnivori (volpi, tassi). Molte specie di uccelli acquatici mangiano sia le rane che i girini (aironi, garzette, cicogne, tuffetti).
I girini sono cibo anche di altri anfibi (tritoni) e degli insetti acquatici (libellule).
Distribuzione e longevità
Una rana comune vive in media 5 anni.
La specie è comune in gran parte dell’Europa occidentale, centrale e orientale. In Italia è presente con certezza solo nella Pianura Padana.
Declino e minacce ambientali
E’ una specie praticamente scomparsa da molti stagni e specchi d’acqua, a causa dell’inquinamento ambientale e delle acque da parte di sostanze tossiche. Anche l’impoverimento delle piante acquatiche ha prodotto un notevole ridimensionamento di questa specie.
Normative e regolamentazioni
Non è possibile cacciare liberamente la rana verde in Italia; la raccolta e l’allevamento sono vietati o limitati dalle normative regionali nonostante la specie sia commestibile. In Lombardia la cattura è consentita entro limiti giornalieri con licenza di pesca ed è vietata durante il periodo della riproduzione dal 1° ottobre al 30 giugno.
Ricordi di un tempo
Ben diversa era la situazione ai tempi della mia infanzia: ricordo la cattura nelle risaie, di notte con la torcia. Oggi queste modalità sono vietate. Le rane servite nelle trattorie e nei ristoranti locali provengono quasi interamente dai paesi orientali.
Testo e Foto Walter Ferrari
Tags: ambienti umidi biologia campagna curiosita inquinamento memorie d infanzia minacciata pianura padana rana verde scomparsa walter ferrari
Category passione-natura not found
----
FTL stack trace ("~" means nesting-related):
- Failed at: @get_category name=cat_name var="cate... [in template "dev.sevendaysweb.com/layouts/macro/utils.ftl" in macro "set_primary_category_color" at line 600, column 7]
- Reached through: @set_primary_category_color c [in template "dev.sevendaysweb.com/layouts/macro/content_suggested.ftl" in macro "hs_contents" at line 970, column 25]
- Reached through: @hs_contents ca, contents_preview, co... [in template "dev.sevendaysweb.com/layouts/macro/content_suggested.ftl" in macro "suggested_category_content" at line 461, column 17]
- Reached through: @suggested_category_content ca, last_... [in template "dev.sevendaysweb.com/layouts/macro/content_suggested.ftl" in macro "suggested_contents" at line 223, column 25]
- Reached through: @query name=name cache=false start=st... [in template "dev.sevendaysweb.com/layouts/macro/content_suggested.ftl" in macro "suggested_contents" at line 221, column 9]
- Reached through: @suggested_contents name=(mpName + "i... [in template "dev.sevendaysweb.com/layouts/macro/content_suggested.ftl" in macro "content_suggested" at line 81, column 41]
- Reached through: @query name="categories_area_sect" ca... [in template "dev.sevendaysweb.com/layouts/macro/content_suggested.ftl" in macro "content_suggested" at line 8, column 9]
- Reached through: @content_suggested bundle.OCDetail, "... [in template "dev.sevendaysweb.com/layouts/macro/content_details.ftl" in macro "content_details" at line 358, column 25]
- Reached through: @content var="c" show_last_content=ca... [in template "dev.sevendaysweb.com/layouts/macro/content_details.ftl" in macro "content_details" at line 118, column 9]
- Reached through: @content_details img_full_width=img_f... [in template "dev.sevendaysweb.com/layouts/default.ftl" in macro "contents_column" at line 9, column 13]
- Reached through: @contents_column [in template "dev.sevendaysweb.com/layouts/macro/skeleton.ftl" in macro "container" at line 412, column 49]
- Reached through: @query name="count_areas" cache=false... [in template "dev.sevendaysweb.com/layouts/macro/skeleton.ftl" in macro "container" at line 254, column 5]
- Reached through: @container context, "[left-mid-", "[c... [in template "dev.sevendaysweb.com/layouts/macro/skeleton.ftl" in macro "html" at line 111, column 33]
- Reached through: @cache sv=search_val [in template "dev.sevendaysweb.com/layouts/macro/skeleton.ftl" in macro "html" at line 66, column 9]
- Reached through: @html cat_layout="home" cat_title=tru... [in template "dev.sevendaysweb.com/layouts/default.ftl" at line 24, column 1]
----
Java stack trace (for programmers):
----
freemarker.template.TemplateException: [... Exception message was already printed; see it above ...]
at it.treis.utils.freemarker.BasicHeadingCategoryDirective.getCategoryByName(BasicHeadingCategoryDirective.java:63)
at it.treis.utils.freemarker.CategoryDirective.execute(CategoryDirective.java:65)
at freemarker.core.Environment.visit(Environment.java:445)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:101)
at freemarker.core.Environment.visit(Environment.java:330)
at freemarker.core.Environment.visit(Environment.java:372)
at freemarker.core.Environment.invoke(Environment.java:775)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:83)
at freemarker.core.Environment.visit(Environment.java:366)
at freemarker.core.IteratorBlock$IterationContext.executedNestedContentForCollOrSeqListing(IteratorBlock.java:291)
at freemarker.core.IteratorBlock$IterationContext.executeNestedContent(IteratorBlock.java:271)
at freemarker.core.IteratorBlock$IterationContext.accept(IteratorBlock.java:242)
at freemarker.core.Environment.visitIteratorBlock(Environment.java:642)
at freemarker.core.IteratorBlock.acceptWithResult(IteratorBlock.java:107)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:93)
at freemarker.core.Environment.visit(Environment.java:366)
at freemarker.core.Environment.invoke(Environment.java:775)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:83)
at freemarker.core.Environment.visit(Environment.java:330)
at freemarker.core.Environment.visit(Environment.java:372)
at freemarker.core.Environment.invoke(Environment.java:775)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:83)
at freemarker.core.Environment.visit(Environment.java:330)
at freemarker.core.Environment.visit(Environment.java:372)
at freemarker.core.Environment$NestedElementTemplateDirectiveBody.render(Environment.java:2900)
at it.treis.utils.freemarker.CategoryCachedQueryResultDirective.execute(CategoryCachedQueryResultDirective.java:202)
at freemarker.core.Environment.visit(Environment.java:445)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:101)
at freemarker.core.Environment.visit(Environment.java:366)
at freemarker.core.Environment.invoke(Environment.java:775)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:83)
at freemarker.core.Environment.visit(Environment.java:330)
at freemarker.core.Environment.visit(Environment.java:372)
at freemarker.core.IteratorBlock$IterationContext.executedNestedContentForCollOrSeqListing(IteratorBlock.java:291)
at freemarker.core.IteratorBlock$IterationContext.executeNestedContent(IteratorBlock.java:271)
at freemarker.core.IteratorBlock$IterationContext.accept(IteratorBlock.java:242)
at freemarker.core.Environment.visitIteratorBlock(Environment.java:642)
at freemarker.core.IteratorBlock.acceptWithResult(IteratorBlock.java:107)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:93)
at freemarker.core.Environment.visit(Environment.java:330)
at freemarker.core.Environment.visit(Environment.java:372)
at freemarker.core.Environment$NestedElementTemplateDirectiveBody.render(Environment.java:2900)
at it.treis.utils.freemarker.CategoryCachedQueryResultDirective.execute(CategoryCachedQueryResultDirective.java:202)
at freemarker.core.Environment.visit(Environment.java:445)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:101)
at freemarker.core.Environment.visit(Environment.java:366)
at freemarker.core.Environment.invoke(Environment.java:775)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:83)
at freemarker.core.Environment.visit(Environment.java:330)
at freemarker.core.Environment.visit(Environment.java:372)
at freemarker.core.Environment$NestedElementTemplateDirectiveBody.render(Environment.java:2900)
at it.treis.utils.freemarker.ContentCachedResultDirective.render(ContentCachedResultDirective.java:201)
at it.treis.utils.freemarker.ContentCachedResultDirective.execute(ContentCachedResultDirective.java:181)
at freemarker.core.Environment.visit(Environment.java:445)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:101)
at freemarker.core.Environment.visit(Environment.java:366)
at freemarker.core.Environment.invoke(Environment.java:775)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:83)
at freemarker.core.Environment.visit(Environment.java:330)
at freemarker.core.Environment.visit(Environment.java:372)
at freemarker.core.Environment.invoke(Environment.java:775)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:83)
at freemarker.core.Environment.visit(Environment.java:330)
at freemarker.core.Environment.visit(Environment.java:372)
at freemarker.core.Environment$NestedElementTemplateDirectiveBody.render(Environment.java:2900)
at it.treis.utils.freemarker.CategoryCachedQueryResultDirective.execute(CategoryCachedQueryResultDirective.java:202)
at freemarker.core.Environment.visit(Environment.java:445)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:101)
at freemarker.core.Environment.visit(Environment.java:366)
at freemarker.core.Environment.invoke(Environment.java:775)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:83)
at freemarker.core.Environment.visit(Environment.java:366)
at freemarker.core.Environment.visitAndTransform(Environment.java:495)
at freemarker.core.CompressedBlock.accept(CompressedBlock.java:42)
at freemarker.core.Environment.visit(Environment.java:366)
at freemarker.core.Environment$NestedElementTemplateDirectiveBody.render(Environment.java:2900)
at it.treis.utils.freemarker.CacheDirective.execute(CacheDirective.java:102)
at freemarker.core.Environment.visit(Environment.java:445)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:101)
at freemarker.core.Environment.visit(Environment.java:366)
at freemarker.core.Environment.invoke(Environment.java:775)
at freemarker.core.UnifiedCall.accept(UnifiedCall.java:83)
at freemarker.core.Environment.visit(Environment.java:330)
at freemarker.core.Environment.visit(Environment.java:336)
at freemarker.core.Environment.process(Environment.java:309)
at freemarker.template.Template.process(Template.java:384)
at org.apache.struts2.views.freemarker.FreemarkerResult.doExecute(FreemarkerResult.java:223)
at org.apache.struts2.dispatcher.StrutsResultSupport.execute(StrutsResultSupport.java:193)
at com.opensymphony.xwork2.DefaultActionInvocation.executeResult(DefaultActionInvocation.java:372)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:276)
at it.treis.smartmedia.navigation.interceptors.PrepareParametersInterceptor.intercept(PrepareParametersInterceptor.java:183)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at it.treis.smartmedia.navigation.interceptors.SubscriptionTokenMatcherInterceptor.intercept(SubscriptionTokenMatcherInterceptor.java:46)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.DeprecationInterceptor.intercept(DeprecationInterceptor.java:41)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:168)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:76)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.DateTextFieldInterceptor.intercept(DateTextFieldInterceptor.java:125)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:253)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:140)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:575)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:142)
at com.thetransactioncompany.cors.CORSFilter.doFilter(CORSFilter.java:209)
at com.thetransactioncompany.cors.CORSFilter.doFilter(CORSFilter.java:244)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:142)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:166)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:88)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:481)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:83)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:643)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:72)
at org.apache.catalina.valves.RemoteIpValve.invoke(RemoteIpValve.java:763)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:344)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:398)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:935)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1831)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:973)
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:491)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63)
at java.base/java.lang.Thread.run(Thread.java:829)
Annunci gratuiti
Lavora con noi
Telegram News
Pubblicità
Redazione