Sunan Latin: | Podiceps cristatus |
Squad: | Grebe-kamar |
Iyali: | Girma |
Additionallyarin ƙari: | Bayanin jinsunan Turai |
Bayyanar mutum da hali. Mafi girma daga grebes. Tsawon Jiki 46-51 cm, fikafikai 85-90 cm. Tana da doguwar fuska, bakin ciki da girma, kai da elongated tare da kunkuntar da kaifi madaidaiciya. A cikin rigunan aure, da alama shugaban ya fi girma ne saboda “sautin kumburi” da kuma murhun da ya fi kama mai kama da ƙaho. Ya fi son zama a cikin ruwa a cikin buɗaɗɗen ruwa, ya mutu cikin haɗari, yana ɗaukar nauyi kuma ba da son rai ba, bayan dogon gudu. A cikin iska, wani lokacin, chomga wani lokacin yakan zama garken da ke da siffofi irin na sihiri wanda yawancin haɓikan ruwa ne (daga grebes irin waɗannan ginin dole ne a gani a cikin sulcus). A cikin kayan hunturu, ya bambanta da launin toka-toadled mai kama da shi a gaban farin gira wanda ke raba ido daga duhu "hat".
Bayanin. A cikin kayan daurin aure, jikin yayi launin toka-fata (bangarorin sun yi launin ja, ciki ya yi fari), wuya ta yi wuya, kawai wani madauri mai duhu ya shimfiɗa a bayan ta, “aƙano” masu launin fata, ja da “ƙaho” baƙaƙen fata ne, “fuskar” farare ne, daga gefunan bakin kawai. duhu ratsi shimfiɗa zuwa ga idanu. Idanun da kansu sunyi ja, kuma launi na baki na iya zama daga launin toka-ƙarfe zuwa ruwan hoda mai haske. A cikin tsuntsu mai tashi, manyan fararen fuka-fukai akan fikafikan suna bayyane bayyane - tare da gashin fuka-fukan na sakandare kuma tare da jagoran ɓangaren reshe, tare da kusanci da ƙarshen sashin sashin. A cikin kayan hunturu, “wassu sannu a hankali” da “ƙaho” sun ɓace, in ba haka ba launin ya kasance daidai da na lokacin rani (kawai launin fata da launin shuɗi ne kawai aka maye gurbinsu da launin toka). A kusan hanya ɗaya kamar tsuntsayen manya a cikin hunturu, kallon cikakke matasa, amma ana rarrabe su da kasancewar alamomin duhu a ɓangarorin wuyansa da kunci. Charshen kajin an karkatar da su gabaɗaya (ciki har da baya har ma da baki), tare da shekaru, rariyoyin a baya sun ɓace, akan kai da wuya ana iya ganinsu da yawa, har sai bayyanar manya. Chan ƙananan kahon sun tsallake fararen fata a cikin sasann bakin da idanu, da kan goshi.
Kuri'a Chomga tana da ƙarfi, tana son yin kururuwa. Mafi yawan lokuta ina jin mirgina "kroro", Kuma da annashuwa - mai ban dariya"dubawa". Kyankar ciwanya suna kusan ci gaba, a cikin wuraren jerawa inda Chomga ya zama ruwan dare, wannan ɓoyayyen ɓoyayyen yanayi ne na bazara.
Matsayi na Rarraba. Harshen jinsi kusan ko'ina cikin Eurasia (a Siberiya - kawai a kudu), masaniyar gida a Afirka, Ostiraliya, New Zealand. Buƙatun Winters suna nan har zuwa yanki mai zafi. A cikin Turai ta Rasha, mafi yalwatacce kuma mafi yawan masara. Ya kai Karelia zuwa arewa, kuma zuwa Tekun Bahar Maliya zuwa kudu. Tsuntsayenmu na hunturu a cikin tekun bakin ruwa na Baƙi da Azov Teas, amma, kamar sauran grebes, a gaban ruwa mai ƙanƙara, cingam na iya hunturu kusan ko'ina. Duk inda ba a saba ba.
Rayuwa. Don kiwo, da chomge yana buƙatar babban tafki mai kyau a cikin kifi. Da yardar rai ya zaunar da wurin tafkuna, tafkunan wuraren kiwo na kifi, har ma a tafkuna na halitta. Yana da mafi yawanci kusa da m (wato, fuskantar da kai) gefen Reed gadaje, gida ne mai iyo na tari, damp shuka sharan gona. Inda akwai chomg da yawa, suna da juriya da kyau da irin nau'in nasu, wani lokacin kuma ana samun mazaunin wasu yankuna kaɗan daga juna. Koyaya, waɗannan masarautun mazaunan, sabanin grebes na baki, basu da tsari. Bayan sun kori kajin, iyayen, a matsayin mai mulkin, ƙaura tare da su a bayansu don buɗe ruwa, inda suke zama har sai yaran sun tashi zuwa reshe. Babban abincin abinci na chomgas shine ƙananan kifi (ba fiye da 15 cm tsayi ba), wani lokacin suna ba da kwari na ruwa ga ƙananan kajin.
Chomga, ko Babban Grebe (Podiceps cristatus)
Bayanin
Canza launi. Namiji da mace a cikin rigunan farauta. Goshin goshi, rawanin, da na baya na baki baqi ne, gashin kann na kunshi da na occipital suna da tsawo kuma, idan yaji dadi, kaho suna fitowa daga bangarorin biyu. Farin fari ya kasance tsakanin farin kai da ido. Ba a ba da amarya ba. Cheeks fari ne. Gashin kunne da ƙananan gashin tsuntsaye sune elongated chestnut-ja, suna haifar da abin wuya, ƙararrawa cikin baƙar fata, halayyar halayya yayin farin ciki. A baya wuya yana da launin toka baƙi. A tarnaƙi da gaban wuyan farar fata farare ne tare da ƙaramar kwalliyar launuka masu launin shuɗi. Jiki na sama yana launin ruwan kasa-baki-baki tare da launin ruwan kwalliyar launin toka a gefun fuka-fukan. Gefen sassan jiki sunyi ja. Twal na jikin, kirji, gindin zama tare da gaban ɓangaren reshe fari ne. Nau'in Farko shine nau'in launin ruwan kasa-launin toka, mai wuta a ƙasa tare da farin sansanonin, ciki wanda akwai farin gudana. Oraramin flywheels fararen fata ne ko fari tare da duhu duhu akan webs ɗin waje. Gefen ya kusan ja ja sosai, tsirinsa launin ruwan kasa ne, bakinsa haske ne. Bakan gizo ja, ɗalibin yana kewaye da zoben orange mai haske. Foreafin hannu da kuɓun yatsun suna waje, gwal mai launin shuɗi, ciki-mai launin shuɗi, kusan launin shuɗi-baki.
Namiji da mata a cikin hunturu. A saman kai mai launin toka ne mai kauri, a kunne. akwai fararen fuka-fukai biyu a kan yadu, ƙaho gajeru, haske yana gudana sama da ido da frenulum. Abin wuya ba ya nan ko ɗan gajeren bayanin da aka zana fuka-fukan baƙi da ja. Cheeks, yankin kunne kuma ya farfado. Wuyan fararen fata ne, a bayanta akwai madaurin toka mai kauri. Jikin na sama yayi duhu tare da faffadar gewayen fuka-fukan a jikin fuka-fukan. Bodyasan jikin da kirji fari. Gefen jiki suna launin toka. Gabaɗaya, maza sun fi girma fiye da mace kuma a kayan saɗani suna da babban abin wuya da ƙaho mafi tsayi.
Kaji mai kadan. Shugaban yana da launin ruwan kasa mai launin shuɗi, babban falon farin yadudduka ya haye saman daga tsakiyar, ƙarin madaidaiciyar fararen fararen fata "suna wucewa tsakanin bangarorin kai ta cikin gira da kuma rami tare da ido .. Akwai alamun launin fari a kan farin makogwaron launuka daban-daban, wuyan an liyi shi da fararen madaidaiciya da raunin launin ruwan kasa. Jaket din da ke ƙasa suna da launin ruwan kasa mai launin ruwan kasa-kasa mai launin ruwan hoda mai haske wacce take da madaidaicin haske, waɗanda suka fi girma suna da rigar duhu launin ruwan jiki .. Jikin jikin da kirji fari ne, akwai kyawawan launuka na fata a jikin amarya, sama da kambi da kuma idanu. kololuwa da babba Bani, gaba daya kewayewa: Bobbin mandible da bakin yatsunsu karfe-launin toka tare da kaomkami ruwan hoda, a gefen gewayen ..
Kayan kaya. Yi kama da kayan hunturu na manya. Farin fari ya kasance a kan goshin baki, ratsan haske akan bangarorin kai a bayan ido da kuma matakin gira. An fitar da abin wuya ta fata daban da launuka daban daban. Farkon kwari sune fari-launin ruwan kasa, tushensu fararen fata ne, mafi zurfin cikinsu suna da farin haske, Firamn kano na fari fari ne da launin shuɗi a saman webs da launin ruwan kasa a gindi. Gaban gefen reshe fari ne, mai cike da launin toka. Gefen yana da ja da launin toka a garesu. Bakan gizo
Farkon hunturu. An kwatanta shi da fararen fari, amma fararen mai duhu mai mottles mai launin shuɗi a cikin launi na gaban ɓangaren reshe. Gefen baya na rauni yana rauni a hankali, kuma rarrabuwarsa zuwa "fayilolin ƙusa" guda biyu an fayyace su. Sau da yawa, muraffun ya kasance akan kai da kuma na sama na jiki.
Farkon bikin aure. Ya bambanta da na ƙarshe ta ƙaramin abin wuya, ba wani farin launi mai launi na gaba na reshen reshe ba.
Miƙa
Kamar yadda yake tare da duka toadstools, manya suna molt sau biyu a shekara - daga kayan daskarewa a cikin hunturu (bazara - kaka - farkon hunturu) kuma daga hunturu zuwa dabbar ta hanyar canjin (marigayi wintering - bazara). Cikakken matakala yana farawa da wuri, a tsawon lokacin farashi a watan Yuni, yana kasancewa har zuwa Disamba, ya danganta da lokacin farawar mutane daban-daban, yawanci zuwa ƙarshen Satumba ko farkon Oktoba, tsuntsaye za su tsinke gaba ɗaya cikin kayan hunturu [Tsuntsaye na Soviet Union, 1951-1954, Gordienko, 1978, Nanzak, 1952]. An maye gurbin Flyworms lokaci guda a ƙarshen Yuli [Gordienko, 1978], a watan Agusta [Hanzak, 1952, Elkin, 1970]; rashin iya tashi sama da wata daya [Hanzak, 1952, Cramp, Simmons, 1977]. Maza sun fara yin motsi sati biyu zuwa uku a baya fiye da mace [Cramp, Simmons, 1977].
Da farko, karamin gashin tsuntsu kwano, sannan gashin fuka-fukan, kaho da abin wuya da aka zubar na karshe. Pre-molting yana farawa ne a cikin hunturu a watan Disamba ko Fabrairu, yana ƙare a cikin manya a ƙarshen Maris ko kuma farkon Afrilu [Tsuntsaye na Soviet Union, 1951-1954, Dementyev, 1952, Cramp, Simmons, 1977]. A cikin tsuntsayen tsuntsaye, yakan jan kunne har zuwa Mayu. Wannan molt din na juzu'i yana kama daskararren kai, wuya, ɓangare na ɓangaren ɓangaren ɓangaren jikin. Farin da yake kwance a jikin mutum yana canzawa sau daya a shekara. A cikin tsuntsayen matasa, ana ƙara molts biyu - daga kayan ƙyalƙyali zuwa kayan kawa da kuma daga kayan kajin a farkon hunturu. Kayan suturun suna sanye da ranar 20 ga watan Agusta - a tsakiyar Satumba [Kozlova, 1947]. An sayi kayan wasan farko na hunturu a watan Oktoba - Nuwamba, wani lokacin kuma a watan Disamba ne, yayin da ƙananan kera ke canzawa ko'ina cikin jiki, ban da kafada da ƙananan bangarorin jiki [Cramp, Simmons, 1977]. Don haka, a cikin shekaru na farko da rabi na rayuwa, chomga molt kusan ci gaba.
Yaɗa
Matsakaicin yankin. Turai, Asiya, Arewa da Afirka ta kudu, Australia da New Zealand. A Yammacin Turai, arewa ta kai 60 ° C. w. a Norway, kadan gaba a Sweden kuma har zuwa 65 ° C. w. a cikin Finland.
Hoto na 36. Yankin rarraba yankin Chomga
a - iyaka na kewayon kiwo, b - ingantaccen bayanin iyakokin iyakar kiwo, c - yankin hunturu. Tallafi: 1 - Podiceps cristatus cristatus, 2 - P. s. infuscatus, 3 - P. s. australis
A cikin USSR - kusan dukkanin sassan Turai, Asiya ta Tsakiya da Kazakhstan, kudu maso yamma da Tsakiyar Siberiya, rabin kudanci Terimorsky Territory.
Hoto na 37. Range na Chomga a cikin USSR
a - iyaka na kewayon kiwo, b - a bayyane iyakar iyakance tsakanin kewayon kiwo, c - wuraren yiwuwar yin farauta, d - wuraren yankuna
Yankin arewa yana rarraba har zuwa gabas daga Unguwar Onega ta arewa zuwa Vologda Oblast zuwa gindin Karshe da bashin Vyatka, ya wuce Urals zuwa gundarin Ob, inda yake da nisan da ke tsakanin latum ɗin Tyumen, Tara da Tomsk. Ari - zuwa yankin Krasnoyarsk (raguwar Minusinsk), a cikin yankin Baikal [Bratsk Reservoir, Angara, Tolchin, 1979] da kuma a Transbaikalia (Torean Lakes, Selenga Delta [Leont'ev, 1965, Tolchin, 1979]). A cewar Amur, babu chomgi. Tana sake fitowa a cikin USSR kawai a cikin ƙananan Iman, a kan Lake. Khanka kuma a bakin tafkunan Kudancin Primorye, inda zai iya yin sheka [Birds of Soviet Union, 1951-1954, Ptushenko, 1962, Leontiev, 1965, Spangenberg, 1965, Ptushenko, Inozemtsev, 1968, Panov, 1973, Ivanov, 1976, Popov, 1977 , Cramp, Simmons, 1977]. Yankin kudu a yankin da ke cikin yankin chomga a ko'ina yana da iyakar kudu da iyakar USSR. Baƙi a cikin manyan lambobi tare da kogin deltas da kuma dukkan manyan kogunan da ke gudana cikin Tekun Baƙi, Azov da Caspian Seas, a cikin Arewacin Crimea [Dementiev, Gladkov et al., 1951-1954], a kan tabkuna da wuraren ajiye ruwa a Azerbaijan, kan manyan tafkuna da wuraren ajiyar ruwa a Kazakhstan, Asiya ta Tsakiya da Yammacin Siberiya tana mamaye duk wuraren da suka dace. A cikin Transcaucasia, tana da gida a Azerbaijan da Armenia (Lake Sevan, marshlands da koguna), kuma ba ta da gida a Georgia (Leister, Sosnin, 1944, Zhordania, 1962]. A Kyrgyzstan, a kan nkuna tabkuna. Issyk-Kul kuma yayi tsauni a tsaunuka a tafkin. Sonkel (3 016 m sama da matakin teku, ya bayyana a cikin 'yan shekarun nan, bayan kammala Ottoman, peled), a cikin Altai a bakin tafkin. Karakul (2,300 m sama da matakin teku) [Abdusalyamov, 1971, Dementiev, 1952, Strautman, 1954, 1963, Dolgushin, I960, Minoransky, 1963, Irisov, Totunov, 1972, Tuaev, Vasiliev, 1972, Oleynikov et al., 1973, Tatarinov, 1973, Kydyraliev, Sultanbaeva, 1977].
A Tsakiyar Asiya, tana da faɗi a kan tafkunan Yammacin Mongolia, watakila a cikin China ne a cikin tafkunan Alak-Nor da Kuku-Nor, a cikin Kashgar [kwafin tarin ZIN na Kwalejin Kimiyya ta USSR, Sudilovskaya, 1973]. A Yammacin Turai, a cikin shekaru 100 da suka gabata, adadin Chomga ya haɓaka zuwa arewa, kuma a wasu wurare yawan tsuntsayen da ke farauta sun ƙaru. A cikin Netherlands, tabbas ba a san chomga ba a ƙarni na 16 - 17. kuma ya bayyana a karni na XVIII. Thearfafa yawancin cakulan a farkon rabin na biyu na karni na ƙarshe akan furcin tsuntsu ya haifar da ƙaddarar lambobi (har 42 nau'i-nau'i a Ingila). Daga baya, a cikin 1900-1925. yawan chomgas ya fara girma cikin sauri, a cikin Burtaniya a 1931 - 2 800 tsuntsaye, 1965 - 4 132-4 734 tsuntsaye, a Netherlands a 1932 - 300 nau'i biyu ko lessasa, 1966 - 3 300-3 500 nau'i biyu, 1967 G. - 3 600-3 700 nau'i biyu, a Belgium - adadin ya fara ƙaruwa bayan 1900, a 1953-1954. - 40 nau'i-nau'i, a cikin 1959 - nau'i-nau'i 50, a cikin 1966 - nau'i-60-70. Yawan adadin kiwo a Ostiryia, Switzerland, Spain, Gabashin Jamus, da kuma wakilan Baltic na USSR suna ƙaruwa. Tun daga farkon 1900s, an sami ci gaba mai yawa zuwa arewa a cikin Finland, a Norway (farkon farawa a cikin 1904, nau'i-nau'i 30 a 1968). A lokaci guda, ba a lura da yanayi da yawa da yawa a Faransa; yawanci ya ragu a wasu yankuna na Jamus (Hesse, North Rhine-Westphalia), wanda a baya aka kasance a cikin Cyprus da Sicily [Oppo, 1970, Cramp, Simmons, 1977, Labaran Turai, 1978 ].
Dalilin canji a cikin kewayon yawa da cakulan a Turai gabaɗayan bayyane - na farko, bin mutum na kai tsaye don manufar shirya pelts, daga baya a karni na 20. canje-canje a mazaunin ruwa - eutrophication of reservoire, hanyar sadarwa, manyan rijiyoyin a Netherlands, damuwa ga 'yan wasa, yawon bude ido da mafarauta a wuraren farauta, yawan amfani da magungunan kashe kwari a cikin 1940-1950s, a cikin shekaru 20 da suka gabata ƙirƙirar babban cibiyar sadarwa na wuraren kariya ga tsuntsayen gonaki. Dangane da yanayin dumamar yanayi gaba daya da aka lura a cikin shekaru 50 da suka gabata, hadaddun dalilai masu dacewa sun zama mafi mahimmanci ga Chomga fiye da yanayin tasirin mummunan tasirin, wanda ya haifar da ƙarar yawan adadin da fadada kewayon. Amma a cikin tsakiyar yankin Turai na USSR, yawan chomg nesting a cikin ruwan halitta ya ragu sosai, kuma a wasu wuraren sun ɓace gaba ɗaya ƙarshen ƙarshen 1940s. A cikin Bashkiria, ya kasance ko'ina a cikin yawa a ƙarshen 19th da farkon ƙarni na 20, yanzu yana faruwa baƙuwa, babu inda yake da yawa [Ilyichev, Fomin, 1979]. A lokaci guda, canje-canje masu mahimmanci a cikin cibiyar sadarwar ruwa da ƙirƙirar ɗumbin yawa na tafki a cikin babban tudun Volga ya haifar da fitowar yawancin tsuntsaye masu farauta a cikin manyan ɗakunan ajiyar wucin gadi [Ptushenko, 1962, Ptushenko, Inozemtsev, 1968].
An ambaci ambaliyar ruwan tare da Ob zuwa 62-65 ° C. sh., zuwa Chukotka (Anadyr), zuwa Iceland, zuwa Azores [kofe na tarin ZIN na Cibiyar Kimiyya ta USSR, Ivanov, 1976, Cramp, Simmons, 1977].
Cin nasara
A cikin USSR, hunturu na kaburbura a adadi mai yawa a Kudancin Caspian, a Tekun Black Black a bakin tekun Crimea da Caucasus, a cikin adadi kaɗan a Tekun Azov, cikin ramuka daban a cikin Asiya ta Tsakiya (Issyk-Kul, samfuran 200-250, wuraren ajiyar ruwa a gefen Uzboy da Kara-Kumsky wani tafki a cikin Turkmenistan, a tafukan ruwa tare da Syr Darya a cikin Tajikistan), a cikin tafkuna da kuma wuraren ajiyar ruwa a Azerbaijan, a cikin 'yan shekarun nan, samfurori na mutum sun ci gaba da yin hunturu a tsarin hydraulic a cikin Latvia, Yammacin Yukren, a kan taskokin Dnieper [Abdusalyamov, 1971, Viksne, 1963, Vinokurov , Tu Aev, Vasiliev ,,, 1972, Mustafayev, 1972, Strokov, 1974, Sabinevsky, Sevastyanov, 1975, Kydyraliev, Sultanbaeva, 1977]. Don yin hunturu, cakulan suna tashi da wuri, tare da cikakken daskarewa da wuraren waha, a cikin Oktoba-Nuwamba. Suna fitowa a kudancin Caspian kusa da bakin gabar Azerbaijan a watan Nuwamba, kuma sun tashi daga hunturu a ƙarshen Fabrairu - tsakiyar Maris [Kozlova, 1947].
Sun bayyana a Tekun Caspian a bakin gabar Turkmenistan a watan Nuwamba, a cikin watan Disamba tsuntsaye sun zama kadan a cikin teku, a jikin ruwayen Turkmenistan jirgin zai tashi daga tsakiyar Oktoba zuwa tsakiyar Nuwamba, tashi daga hunturu a cikin Caspian yana faruwa ne a farkon Maris, ƙaura akan ruwan jikin Turkmenistan a rabin na Maris —A farkon Afrilu [Dementiev, 1952, Vasiliev, 1977]. Sun isa bakin Bahar Maliya a farkon - a ƙarshen Satumba - a tsakiyar Oktoba, ana tsare su cikin manyan taro, suna komawa zuwa ƙarshen Maris kuma suna tashi har tsakiyar Afrilu [Strokov, 1974]. Yankin Azerbaijan a Tekun Caspian an warwatsa, 98-102 samfurori a 1 km2 [Mustafayev, 1972].
A Yammacin Turai, suna fitowa a adadi mai yawa a gefen Tekun Atlantika a watan Oktoba-Nuwamba kuma suna nan har zuwa ƙarshen Fabrairu - farkon Maris, kuma har zuwa winters dubu 22 a kann manyan tabkuna a kowace shekara (Geneva, Bodene, Neuchatel). Kusan akwai kadan a lokacin hunturu a yamma da Kudancin Rum, kusa da bakin tekun Fotugal, a bakin tekun Maroko, watakila an rubuta sunayen Palaearctic chomga a cikin Senegal. Dubunnan 'yan chomg suna tafe a kan Bahar Maliya lokacin sanyi a bakin gabar Turkiyya, a Caspian - a bakin tekun, Iran. Ba su da yawa a lokacin hunturu a cikin Bahar Rum, a gabashin Rum [Cramp, Simmons, 1977].
Hijira
A wuraren farauta, chomga ya bayyana da wuri, a cikin Ciscaucasia a farkon bazara a tsakiyar Fabrairu, yawanci yawan ƙaura yana faruwa ne a cikin shekaru goma na uku na Maris - a farkon Afrilu [Oleinikov et al., 1973]. A tekun Bahar Maliya a bakin tekun Caucasus da ke kusa da Poti, chomgi ya tashi cikin manyan garkuna har tsakiyar watan Afrilu [Vronsky, Tomkovich, 1975]. A arewacin Priazovye (Berdyansk, Genichensk), yawan jirgin Chomga bisa la’akari da dogon lokaci shine Maris 21 zuwa 23 [Lysenko, 1975]. A shekara ta 1976, yawan garken chomg ya tashi a kan tafkin Kanevskoe a ranar 26 ga Maris - Afrilu 4, tsuntsaye sun tashi cikin garken mutane 16-60 a tsayinsa ya kai 20 m, an lura da hanyar a bayyane da safe daga 6 hours 30 minutes to 8 hours 45 minutes.
A cikin yankuna na yamma na Ukraine sun isa ƙarshen Maris - a farkon shekaru goma na Afrilu [Strautman, 1963, Tatarinov, 1973]. Suna tashi zuwa Belarus daga farkon zuwa ƙarshen Afrilu [Fedyushin, Dolbik, 1967]. A tsakiyar Volga (Tatar Automatous Soviet Socialist Republic), Chomga ya bayyana har sai an buɗe koguna a farkon rabin Afrilu, taron farkon shine ranar 6 ga Afrilu [Popov, 1977]. A cikin yankin Kursk, chomga na farko ya bayyana dangane da yanayin bazara daga ƙarshen Fabrairu zuwa farkon Maris, amma jirgin da aka ambata yana faruwa ne a tsakiyar watan Afrilu. A cikin yankin Moscow a cikin shekaru daban-daban daga 15 Maris zuwa 5 ga Mayu 5, amma ba a bayyana karin lokaci a nan ba. A cikin yankin Perm a cikin rafin kogin. Lasashe sun iso 10 Mayu [Kozlova, 1947]. A Lithuania kusa da Palanga, an yi rikodin chomgs a tsakiyar Afrilu; suna sauka ƙasa da saman ruwa sama da teku [Petraitis, 1975]. A Estonia, kaburbura suna fitowa a cikin lambobi masu mahimmanci a farkon shekarun Afrilu, kodayake a wasu shekaru wasu mutane sun tashi a cikin rabin na Maris (Maris 19, 1957, Maris 28, 1950). Hijira na faruwa a ƙarshen Afrilu ko farkon Mayu [Jogi, 1970].
A kan tabkuna na arewacin Kazakhstan (Naurzum da kuma duk baƙin ciki na Turgai), chomigas ya bayyana har sai kankara ta narke gabaɗaya lokacin da manyan faranks suka tashi a ranar 11 ga Afrilu, 23, kuma ƙaura suna faruwa a ƙarshen Afrilu - farkon Mayu, suna tashi cikin rukuni na tsuntsaye 39, wani lokacin garken har zuwa 20 [ Elkin, 1975, Gordienko, 1978]. A cikin kudu sosai na Kazakhstan (Turkestan), ƙararrakin farko sun bayyana a ƙarshen Fabrairu ko farkon Maris, tashi duka Maris da farkon farkon Afrilu, arewa - zuwa Syr Darya kusa da Kyzyl-Orda - a ƙarshen Maris kuma tashi duk Afrilu, a cikin Ural delta da kan Embe ya fara bayyana ne a tsakiyar watan Afrilu, ya isa Ili delta a farkon rabin Maris, akan Zaysan a tsakiyar Afrilu [Dolgushin, 1960]. A Kyrgyzstan, da yawa a cikin bazara a kan jirgin zuwa Lake. Issyk-Kul a cikin 1958 a ƙarshen Maris - Afrilu, ya ɓace ranar 17 Afrilu [Yanushevich et al., 1959]. A lake Sonkel Chomga ta isa tsakiyar watan Afrilu, tare da daskarewa a tafkin a ƙarshen Nuwamba, tayi ƙaura don hunturu, watakila a tafkin. Issyk-Kul, sabili da haka, yana yiwuwa a iya cewa yawan mutanen Kyrgyz na Chomg suna jagorantar yanayin rayuwa mai tsayayye [Kydyraliev, Sultanbaeva, 1977].
A Yammacin Siberiya a bakin tafkin. Erarancin Chan, Chomgy ya tashi a cikin shekaru goma na uku na Afrilu, a buɗe ƙofofin ruwa, tsuntsayen keɓewa na farko sun bayyana, sannan nau'i-nau'i da kuma rukuni da yawa, jirgin da aka ambata yana faruwa ne a cikin kwanaki goma na farko na Mayu, sarara ke tashi da daddare, a saman tabkuna, a tsawan 20-50 m, a yamma tsuntsaye wanda aka samo kawai akan ruwa [Koshelev, 1977].
A cikin Transbaikalia, tafkunan Torean suna da yawa a lokacin ƙawancin bazara daga 23 ga Afrilu zuwa 12 Mayu [Leont'ev, 1965]. A Kudancin Primorye, yana birgima a kan tabkuna a cikin karamin adadin a farkon rabin Maris - rabin farko na Mayu [Panov, 1973].
Chomgy farawa lokacin kaka na kaka, daga baya fiye da sauran grebes. A cikin wuraren ajiya da yawa, ana jinkirta su har sai daskarewa a Nuwamba-Disamba. A Kudancin Primorye, hanyar da ke kan tabkuna ba ta da ƙarfi sosai, a ranar 11 ga Satumbar 12, 1961, an lura da loners da ma'aurata, har zuwa farkon kwanaki goma na Nuwamba, an yi rikodin tsuntsaye guda [Panov, 1973]. A kan tafkunan Torean a Transbaikalia, ƙaura lokacin kaka yana faruwa daga Agusta 10 zuwa Satumba 15 [Leontyev, 1965]. Daga tafkin Sonkel tashi daga ƙarshen Nuwamba, watakila don lokacin hunturu a Issyk-Kul [Kydyraliev, Sultanbaeva, 1977]. A kan tafkunan Baraba, motsawar kaka yana farawa a farkon watan Agusta, lokacin da chomga ya bayyana akan jikin ruwa marasa kyau, tashi daga farawa daga ƙarshen watan Agusta, ya kai kololuwa a farkon farkon Satumba, yana zuwa ƙarshen Satumba, ƙarshen yana haɗuwa har zuwa 20 ga Oktoba, matasa suna tare har sai tashi. tsuntsaye manya kuma, wataƙila, ɗayan chomg yana cikin ƙungiyoyi na dangi na tsuntsaye biyu zuwa huɗu, amma da yawa suna motsa shi kaɗai kuma da wuya akwai gungun tsuntsaye bakwai ko fiye da Shchechelev, 1977].
Har ila yau jirgin yana faruwa a cikin dare, yayin da rana akwai rauni ƙaura yin iyo a kusa da koguna da kwalaye. A kann magudanun Naurzum, tsuntsayen da suka manyanta zauna tare da broods har zuwa farkon - ƙarshen Satumba, sannan kuma su tashi, matasa su kasance su kaɗai, suna tashi a ƙarshen Satumba - farkon Oktoba [Gordienko, 1978]. A kan tabkuna na turmutsitsin turgai, babban jirgin sama na chomg yana tafiya tsakiyar tsakiyar Oktoba [Elkin, 1970]. A cikin Tekun Caspian, kusa da Mangyshlak suna tashi cikin kananan kungiyoyi a tsakiyar Oktoba [Zaletaev, 1962]. A rabin rabin Satumba - a farkon rabin Oktoba suna tashi cikin lambobi masu yawa a kudancin Kazakhstan tare da kwarin kogin. Ko kuma, a Balkhash, a gefen Syr Darya, a gefen gabar Aral da Caspian Teas, a wannan lokacin suna tashi da yawa cikin garken mutane 10, kuma a cikin Caspian ta Arewa suna tarawa adadi mai yawa kuma ana ajiye su cikin manyan garken a bakin kogin. Urals sun lura da ƙaura ta yin iyo [Dolgushin, 1960]. A cikin Turkmenistan, suna tashi daga tsakiyar Oktoba zuwa tsakiyar Nuwamba a gefen Amu Darya da Uzboy, da kuma gabar tekun Caspian - galibi a watan Nuwamba [Dementiev, 1952, Vasiliev, 1977].
A cikin yankunan Moscow, Ryazan da Kursk, chomga suna zama a wuraren da suke zaune har zuwa ƙarshen watan Agusta, kuma a watan Satumba sun ƙaura zuwa wasu wuraren ajiyar, daga ƙarshen Satumba sun fara yawo sosai, hanyar da aka ambata a cikin yankin Moscow yana faruwa ne a ranar 13 ga Satumba - 28 ga Oktoba - 23 ga Nuwamba 23 kuma an sananne sosai 22 –A Oktoba 27, tsuntsaye na ƙarshe ana samunsu kusan har zuwa ƙarshen Oktoba, kuma a cikin Kursk - har zuwa tsakiyar Nuwamba [Ptushenko, Inozemtsev, 1968]. A cikin arewa-gabashin Ukraine, chomga tashi har zuwa ƙarshen shekaru goma na biyu na Disamba; a Yammacin Yammacin Ukraine, tashi da tashi suna faruwa a cikin shekaru daban-daban daga ƙarshen Satumba zuwa farkon Disamba [Strautman, 1963, Matvienko, 1978]. A cikin Kudancin Ukraine, motsi na kaka ya zama sananne daga ƙarshen Agusta zuwa farkon Satumba, lokacin da loners, garken 3-5, da wuya kusan mutane 40 suka bayyana a kan koguna da wuraren rami inda ba a da, canji mai faɗi a tsakiya da ƙananan Dnieper yana faruwa a watan Oktoba, mafi yawa - a farkon shekarun farko ko na uku na wannan watan. A gefen tekun Estonia, jirgin sama mai alamar chomgi yana tashi daga ƙarshen Satumba zuwa tsakiyar Disamba, mafi yawan gaske a farkon Oktoba, amma a gaba ɗaya yawan adadin mashigin ruwan chomg yana da ƙanƙan - na tsawon watan da aka lura a 1960, samfurori 112, a 1962 - 99, mafi yawan adadin chomg yana tashi da maraice kafin faɗuwar rana [Yogi, 1963, Jogi, 1970].
Sakamakon bandeji na chomg a cikin Turai ya nuna cewa a farkon faduwar rayuwa a watan Agusta-Satumba, tsuntsayen da suka tsinke a cikin yankunan tsakiyar yankin na RSFSR, jihohin Baltic, Jamhuriyar Demokradiyyar Jamusawa, da Poland suna yin ƙaura sosai a cikin hanyoyi daban-daban, ciki har da arewacin 100-120 km [Kishchinsky, 1978]. Daga baya, a watan Oktoba-Nuwamba, suna tashi kudu da kudu maso gabas, suna bayyana a cikin tsakiyar yankuna na Ukraine, a gefen arewacin tekun Bahar Maliya da jihohin Baltic, da kuma hunturu a watan Disamba-Janairu a arewacin Rum. A cikin bazara na watan Afrilu-Mayu, suna sake bayyana a yankin Black Sea. Chomgy nesting a cikin Tekun Azov, har zuwa ƙarshen kaka, zauna a wurin da ake yin wuraren nesting, da kuma hunturu kusa da Bahar Maliya. Kayan Chomks a cikin Volga delta tashi don hunturu zuwa tekun Bahar Maliya na Caucasus.
A bayyane yake, yawan jama'ar yammacin Siberian da Kazakhstani na chomg masu cin nasara a cikin Caspian, babu alamun dawowa kai tsaye da ke tabbatar da wannan ra'ayi, amma Chomg yana yin kara akan shinge a kan layin yankin Omsk ya nuna mafi yawan yamma da kudu maso yamma na yawo na gida a cikin Satumba. Oktoba. Kayan rabe-rabe na Yammacin Turai sun nuna cewa wasu daga cikin tsuntsayen daga lokacin hunturucin Scandinavia a saman gabar tekun Baltic da Netherlands, kodayake yawancin suna tashi kudu maso gabas ta hanyar Ukraine da tekun Bahar Rum zuwa Bahar Rum. Chomgy daga Jamus, Netherlands da tsakiyar Faransa suna tashi zuwa kudu don yin hunturu a kan tafkunan Switzerland, kuma nesting da Switzerland suna faruwa a watan Nuwamba - Maris a gefen tekun Bahar Rum da Atlantika na Faransa, Italiya, Austria da Bavaria [Cramp, Simmons, 1977].
Lambar
Abu mara kyau ne kuma ya dogara da rarraba wuraren zama na mazaunan kiwo. Jimlar chomg na farauta a Estonia kusan 1,400 nau'i ne [Oppo, 1970], a cikin 1951-1957. ya yi daidai da 775 nau'i-nau'i [Oppo, 1969]. Yankin Chomgi a nan tsibirin teku, kusa da gabar teku, a kan tafkuna a kudu maso gabashin Estonia, ku guji wuraren sakewa na ƙasa da kadada 20 tare da yanki kuma kusan galibi suna mamaye tabkuna tare da yanki fiye da kadada 50, matsakaicin yawan jama'a yakai 5 nau'i a kan kadada 100 na tabkin lake. A karkashin yanayi mai kyau, ana kirkirar mazauna yanki na kusan 100 nau'i, yawanci tare da gulls lake (Oppot 1970]. A kan jikkunan ruwa a cikin yankin tsakiyar Turai na RSFSR, a cikin Volga-Kama Territory, a Belarus, gida mai gida daban.
A tsakiyar yankin na Volga delta, yawan su ya fi girma, nau'i-nau'i 1-3 a cikin 100 ha [Markuse, 1965]. A cikin tabkuna na arewacin Kazakhstan, a cikin Naurzum, chomgy ya kai girman 0.2-1.5 nau'i biyu a hectare na ciyawa mai girma [Gordienko, 1978], nau'i-nau'i 11 cikin hectare 100 na ruwa a cikin tabkuna tsakanin kogunan Ubagani Ishim [Elkin, 1975]. A Kudancin Turkmenistan, kan tafki a tafkin. Karamin Delili tare da yanki mai kadada 700 a 1973 wanda aka yiwa kusan nau'i-nau'i 45, a 1974 - 5-6 nau'i-nau'i, a 1975 - game da nau'i-nau'i 33, an lura da samuwar wuraren mulkin mallaka na chomg anan - har zuwa nau'i-nau'i 8 a 1 ha [Karavaev, 1979 ]. A cikin ambaliyar ruwan kogin. Beisug a cikin yankin Krasnodar a 1967 a kan hanya na kilomita 15 a cikin tsinkaye 40 m, an yi amfani da makwancin chomg shida, cikin sharuddan daukacin yankin ambaliyar ruwa (dubu 20 ha), kusan nau'i-nau'i na 5,000 na mazaunan chomg ya kamata a zauna a nan [Kostoglod, 1977]. A kan tabkuna na gandun dajin Baraba-mai kusa da tafkin. Chanaramar Chan yawan kiwo chomg yana da ɗan ƙarami, akan tafkin. Beluga tare da yanki mai girman hekta 600 a 1975, nau'i-nau'i guda 15, akan masu lambar Zinare 4X1 a cikin girman a 1975 - nau'i-nau'i [Koshelev, 1977]. A lake lake Sonkel tare da yanki na 292 km2 a 1974-1975 kusan nau'ikan chomg 100 an yi la'akari dasu [Kydyraliev, Sultanbaeva, 1977]. A cikin Wuraren Czechoslovakia tare da yanki mai girman hekta 100, matsakaiciyar ƙimar ita ce nau'i nau'i biyu na 4.2, kuma cikin ɗakunan karamin yanki - nau'i-nau'i 8.9 [HanzakT 1952].
A cikin ƙasashe da yawa na Yammacin Turai, akwai bayanai game da adadin adadin kudan zuma da canje-canjen tarihinta. Bayan faduwarsa da kyau a tsakiyar karni na 19, wanda ya zama sanadin warwatsewar grebes saboda yawan buƙatar kumburin tsuntsaye daga farkon karni na 20, ya fara ƙaruwa daga ɗarurruwa da dubunnan nau'i-nau'i a cikin 60s. A Ingila a cikin 1860 akwai nau'i-nau'i kawai 32, a cikin ɗaukacin Biritaniya a 1931 - 2 800 tsuntsaye kuma a cikin 1965 - 4 132-4 734 tsuntsaye, a cikin Netherlands a 1932 - kusan 300 nau'i-nau'i, a 1966 - 3 300-3 500 nau'i-nau'i, a cikin 1967 - 3 600-3 700 nau'i-nau'i. Jimlar a wasu ƙasashe: Belgium - 60-70 nau'i-nau'i (1966), Norway - kimanin nau'i-nau'i 50 (1968), Denmark - 2,200-200 nau'i-nau'i (1960-1967), Sweden - kimanin nau'i-nau'i 500 (kafin 1971), Finland - kimanin 5,000 nau'i-nau'i (har zuwa 1958), Jamus: Baden-Württemberg - aƙalla 1250 nau'i (1968), Bavaria - kusan 800 nau'i-nau'i (1968-1970), Hesse —54-62 ma'aurata (1964-1966), Spain - ma'aurata 6-12 (shekarun 1960), a cikin Arewacin Afirka a Tunisiya a bakin tafkin. Kelba - nau'i-nau'i 60 (1968) [Cramp, Simmons, 1977], Austria - nau'i-nau'i 50 a 1970, nau'i biyu a 1978 [Labaran Turai, 1978]. Sakamakon haka, tun daga farkon karni na 20, an lura da karuwar yawan Chomg a Turai, da kuma yaduwar yankin zuwa arewa. Wannan ya faru ne sakamakon yaduwar sassan jikin ruwa, wanda ya dace da wadannan tsuntsaye, halittar babban tafki iri iri, da kuma kariya ta mazaunan tsuntsayen ruwa, musamman cikin shekaru 20 da suka gabata.
Abinci mai gina jiki
Ba kamar sauran nau'o'in grebes ba, ƙarar chomga galibi tana kan kifi. Akwai bambance-bambance da aka sani a yanayin yanayin ciyarwa a jikin ruwa daban daban tsakanin kuma yawan mutanen Chomgas. A cikin tabkuna na Naurzum, chomga sune ƙarancin cin kifi. Kifi ya zama sama da kashi 1.2% na dukkanin kayan abinci kuma ana samun shi ne kawai a cikin kashi 12.4% na ciki, tushen abinci shine tushen tsofaffin ƙwaro da kwari (78 da 50% na haɗuwa), crustaceans, larvae of sauro-saro, mollusks, sauro manya. , caddis kwari, gizo-gizo [Gordienko, Zolotareva, 1977]. Daga Afrilu zuwa Agusta, Chomga a Ust-Manych Reservoir a yammacin Ciscaucasia shine ke ciyar da kifi (pike, perch, rudd, bream, da sauran su), wanda yakai 65.8% na nauyin abinda ke ciki, ko kuma kashi 42% na kayan abinci. Kwayoyin cuta suna da nauyin 23.7% na abinci (ciki har da 7.3% - gwoza, 1.5% - kwari, 1.2% - jami'an diplomasiyya), amma sun fi rinjaye da adadin abubuwa (84,3%). A watan Afrilu-Mayu, asusun kifi na kusan 50% na abinci, a watan Yuni-Agusta - fiye da 70%, wannan ya faru ne saboda gaskiyar cewa bayan kyankyashe, Chomga ya shiga zurfin ruwa ya isa kuma ya kewaya [Oleinikov et al., 1973]. V. K. Markuse, wanda ya gudanar da bincike na musamman game da ciyar da grebes a gonakin kifi mai tsiro a cikin tsakiyar Volga delta, ya gano cewa tushen ciyar da chomga akwai kifi (51 - 90% na nauyin abinci gabaɗaya a cikin manya da kashi 32 cikin kajin).
A watan Mayu, an cinye kifin sako, a cikin watan Yuni (bayan fitowar kifin cinikin kasuwanci daga ilmeni), matattarar kifin cinikin matasa ya kai kashi 50% na kayan abinci, a watan Yuli-Agusta wannan adadin yana ƙaruwa sosai. Chomgi ku ci mafi yawan adadin ƙwayoyin gama gari na irin kifi gama-gari 3-8 cm, ƙarancin - Pike perch 2.5-3 cm, ƙasa da sigar fata a cikin chomg da ba a samu ba. Yana da halayyar cewa a waje da masunta, da chomga kama yafi na yara pike 9-16 cm tsawo. Daga cikin abubuwan motsa jiki, babban rabo a cikin ciyar da Chomg ya faɗi akan ƙwayoyin tsofaffi da lardin su. Koyaya, yana da wuya a iya magana game da cutar ƙarancin chomgas a wannan yanki, har ma da yanayin yanayin kamun kifayen al'adu, saboda yawan adadin ƙananan ƙwayoyin carp na kowa, Chomgis ya ci 0.04%, kuma zander - 0.24%. Dangane da bincike game da cututtukan chomgas 87 da aka samu a cikin watanni daban-daban na shekara a kudu, yamma da yankuna na tsakiyar Ukraine, yawan kifaye da kwari a cikin abincin sun kusan iri ɗaya.
Daga cikin kifin, nau'in ƙimar low-darajar - gobies, narkewa da dace; tsakanin kwari - weevils, ruwa irin ƙwaro, gwoza ƙasa, da iyo (Smogorzhevsky, 1979). A kan tafkuna a Czechoslovakia, babban abincin chomga shi ma kifi ne (kashi 83%), rarar da ke da kusan cm 8 tana cin nasara [Hanzak, 1952]. A Yammacin Turai, kashi 60-90% na chomg shima suna dauke da kifi (roach, bleak, gudgeon, perch), kuma a cikin ruwa, gobies, herring, Stickback, cod, da cyprinids. Hakanan suna cin abinci mai yawa na kwari na ruwa, ƙasa da crustaceans, mollusks, polychaetes, frogs, da tadpoles. Wasu lokuta, ana shuka tsaba da sauran tarkace na shuka a cikin adadin da za'a iya godiya. Manyan kifi da daskararre kullun ana kawo su a farfajiya kuma, bayan an wuce shi tsakanin jaws, ana haɗiye shi daga kai, an hadiye wani kifi a ƙarƙashin ruwa [Cramp, Simmons, 1977].
A cikin hunturu, suna ciyar da abinci na musamman game da kifi [Yanushevich et al., 1951, Abdusalyamov, 1971, Cramp, Simmons, 1977].
Suna ciyar da hanyoyi da yawa - ruwa, tattara abinci daga farfajiyar ruwa da tsirrai na ruwa, a cikin ƙasa mai cike da ruwa, suna rage kawunansu da wuya a ƙarƙashin ruwa, kamo kwari da kwari a cikin iska, kukan kifaye da kwari daga dunƙule na tsire-tsire masu ruwa tare da motsin ƙafar ƙafafunsu sannan kuma kama su cikin ruwa [ Cramp, Simmons, 1977, Gordienko, Zolotareva, 1977]. Ruwan Chomg shine babbar hanyar samun abinci. Suna nutse a cikin wuraren bude ruwa (kamar yadda akasin launin toka-mai daɗi, wanda ya fi son ciyar da ciyayi a lokacin bazara, bazara da kaka). Mitar ruwa a gabar ruwan Naurzum sau biyu zuwa uku a minti daya, yin iyo sama da 5-20 m, kuma a karkashin ruwa ya kai matsakaita 17,4 s [Gordienko, 1978]. Dangane da wasu ma'aunai, a matsakaita, suna ciyar da 26 s a karkashin ruwa, daga 15 zuwa 41 g, matsakaicin 56 s [Hanzak, 1952], daga cikin rarar 450 a cikin tafki guda a matsakaita 19.5 s, daga 5 zuwa 30 [Simmons, 1955]. Lokacin da aka kashe karkashin ruwa ya dogara da zurfin kandami da yawan abinci. Yawancin lokaci nutse har zuwa zurfin 1-4 m, kodayake a bakin tafkin. An san Zempach a Switzerland don shari'o'i 161 na cin chomg a cikin raga zuwa zurfin 30 m. Babu shakka, a cikin hunturu suna nutsewa cikin zurfi a cikin mafi yawan lokuta fiye da sauran yanayi na shekara [Cramp, Simmons, 1977].
Abokan gaba, dalilai masu illa
Abokan gaba na Chomga a lokacin farawar sune "tsuntsaye iri-iri" kamar duk sauran tsuntsayen da suke shugabansu akan ruwa, daga cikinsu shine wurin farko na wannan taron mutane da wata mai fadama, wanda ke kusan kashi 20% daga cikin clamgs ɗin. 30% na duk masonry sun mutu sakamakon canji a matakin ruwa a tafki, wani sashin ya mutu saboda wasu dalilai. Mahimmancin mutuwar jaket masu saukar ungulu daga mafarauta, gami da manyan kifayen da aka yanke, da kuma yanayin yanayi.Don tashi zuwa ga reshe, kajin 2-2.3 na kowane tsuntsayen tsuntsaye na wanzuwa. Wannan ya zama isasshen don sabuntawar jama'a na jama'a, amma Chomga ta fada cikin yanayin haɗari idan an ƙara wasu sababbi cikin abubuwan da suka shafi mummunan yanayin, alal misali, tsanantawar mutum ko mutuwa sakamakon hulɗa da kai tsaye.
Farauta kai tsaye don toadstools yanzu babu. Sukan yi ja da baya, ba da gangan ba, abincinsu ba ya dandanawa.
Yanzu manyan grebes suna mutuwa a tarbar kifi, duka a wuraren farauta a manyan tafkuna da kuma filayen hunturu. Toadstools, ciki har da Chomga, sun sha wahala sosai sakamakon zaluntar tsuntsayen masu cin kifi 1, wadanda ake zargin sun lalata tushe na kamun kifi na al'adu. Kamar yadda bincike na musamman a cikin Volga delta ya nuna, cutarwarsu ba zata iya yin tasiri wurin haifuwa irin ta kifi ba. Saboda haka, duk da ƙirƙirar a cikin yankin Turai na USSR a cikin shekaru 30v na ƙarshe na babban ɗakunan ajiya na wucin gadi, chomga kusan ko'ina ya zama tsuntsayen marasa galihu. A Yammacin Turai, tsarin magance wuraren ajiyar ruwa, ƙirƙirar ɗumbin ɗakunan ajiya na wucin gadi da kuma kiyaye kyakkyawan tsuntsaye: gaba ɗaya, da kuma kariya ga mazaunan tsuntsayen ruwa musamman, sun haifar da ci gaba da yawaitar adadin kiwo a cikin shekaru 20 da suka gabata.