Veličina pologa i jaja crvenokljune čigre Sterna hirundo u morskim i slatkovodnim kolonijama Republike Hrvatske

master's thesis

• Title (english): Clutch and egg size of the common tern Sterna hirundo in marine and freshwater colonies in the Republic of Croatia
• Author: Toni Kočevar
• Mentor: Jelena Kralj (mentor)
• Committee member: Jelena Kralj (predsjednik povjerenstva)
• Committee member: Zoran Marčić (član povjerenstva)
• Committee member: Antun Alegro (član povjerenstva)
• Committee member: Jasna Lajtner (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2024-11-28, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Crvenokljuna čigra Sterna hirundo migratorna je ptica iz porodice Laridae koja se gnijezdi
kolonijalno na morskim i slatkovodnim staništima. Karakteriziraju ih mali broj jaja (prosječno tri)
i asinhrono izlijeganje ptića. To podrazumijeva redukciju veličine jaja ovisno o vremenu polaganja,
čime se smanjuje šanse za preživljavanje ptića. U istraživanju veličine pologa i jaja crvenokljunih
čigri, podaci su prikupljeni iz četiri slatkovodne i šest morskih kolonija u Republici Hrvatskoj
tijekom 2021. – 2024. godine. Izmjerene vrijednosti visine i širine jaja korištene su za izračun
volumena jaja. U analizi su korištena četiri nezavisna parametra: godina, stanište (morsko ili
slatkovodno), područje (dolina Save i Drave te Sjeverni i Srednji Jadran) i vrijeme polaganja
pologa (rani ili kasni polozi). U analizi veličine pologa u vrijeme polaganja nije uključeno, ali je
uključena veličina kolonije. Statistička analiza provedena je u programskom jeziku R 4.4.0
primjenom višestruke linearne regresije. Utvrđene su značajne razlike u ukupnom volumenu i
volumenu najvećih jaja ovisno godini, pri čemu su veća jaja zabilježena tijekom 2023. i 2024.
godine, što ukazuje na lošije uvjete gniježđenja 2021. i 2022. Značajne su razlike utvrđene i za
redukcije veličine srednjih i najmanjih jaja, pri čemu su najveće redukcije zabilježene u kasnim
polozima morskih kolonija, što ukazuje na lošije uvjete u morskim staništima, ali i općenito tijekom
kasnog gniježđenja. Veličina kolonije nije značajno utjecala na veličinu pologa, koja je najviše
ovisila o području gniježđenja čime se dodatno ističe utjecaj staništa na gniježđenje ove vrste.

Abstract (english)

The common tern Sterna hirundo is a migratory bird from the Laridae family that nests colonially
in marine and freshwater habitats. It is characterized by a small number of eggs (an average of
three) and asynchronous hatching of chicks. This results in a reduction of eggs depending on the
timing of laying, subsequently decreasing the survival chances of the chicks. In this study of clutch
and egg size of common terns, data were collected from four freshwater and six marine colonies in
Croatia between 2021 and 2024. The measured values of egg height and width were used to
calculate egg volume. Four independent factors were defined for the analysis:year, habitat (marine
or freshwater), region and early or late nest). In the analysis of clutch size, the late nest parameter
was replaced by the colony size. Statistical analysis was conducted in R 4.4.0 using multiple linear
regression. Significant differences were found in the total volume and volume of the largest eggs
depending on the year, with larger eggs recorded in 2023 and 2024, indicating poorer nesting
conditions in 2021 and 2022. Significant differences were also found for reductions in medium and
smallest eggs, with the highest values recorded in late clutches of marine colonies, suggesting
poorer conditions in marine habitats, as well as in general during late nesting. Colony size did not
significantly affect clutch size, which was primarily dependent on the region parameter, further
emphasizing the impactof habitat on the nesting of this species.

• Keywords: Laridae; gniježđenje; reproduktivni uspjeh; stanišni utjecaji; konzervacija
• Keywords (english): Laridae; nesting; reproductive success; habitat impacts; conservation
• Language: croatian
• URN:NBN: urn:nbn:hr:217:195737
• Project: Number: IP-2020-02-8793; Title: Kopno ili more: ekološki i genetički aspekti izbora staništa crvenokljune čigre; Title: Land or sea: ecological and genetic aspects of habitat choice in the Common Tern; Acronym: KiM: ČIGRE; Leader: Jelena Kralj; Jurisdiction: Croatia; Funder: Hrvatska zaklada za znanost; Funding stream: Research Projects
• Study programme: Title: Experimental Biology-University graduate programme; Study programme type: university; Study level: graduate; Academic / professional title: sveučilišni/a magistar/magistra eksperimentalne biologije (sveučilišni/a magistar/magistra eksperimentalne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2025-02-27 11:40:31