| Abstract | The population of pigeons (Columba livia) and crows (Corvus spp.) is overrepresented
in urban areas. Both species are considered as pests. Crows are extremely intelligent and have
a role in reducing the population of smaller bird species. Secondly, crows and pigeons are
responsible for the damages and contamination of buildings, monuments, etc. Furthermore,
both are recorded to carry pathogens and therefore pose public health and ecological concerns.
Therefore, the aim of the study was to analyze and observe the effect of using trained raptors
on the population of urban crows and pigeons. The study took place in the factory Valipile in
Dumovec, Zagrebačka county, Croatia. The study was divided in three phases. Phase one was
the monitoring of undisturbed pigeons and crows in the area, for eight days. In phase two,
raptors (Harris’s hawks) were released for four times (2 x 2) with varying intervals. There was
5 days interval between two raptors flights. Third phase started five days after the second one
and included four ousterings. Intervals between first and second, and third and fourth one was
one day, while interval between second and third was seven days. Presence of pigeons and
crows was monitored non-invasively using three phototraps: two Reolink Go Plus models, and
one Scout Guard, model Boly BG590-24mHD. In the first phase, we observed high numbers
of pigeons in the morning until midday (8 a.m. to 1 p.m.). Pigeons were more present at the
factory in October, probably due to arrival of the harvested corn and their preparations for
winter. During the second phase of the study, after each hawks´flight a sharp decline in pigeon
numbers were observed but the following day pigeons returned in ˝normal˝ numbers. In the
firts part of the third phase, hawks have induced decline in pigeon numbers during the flight
day, while in second part this decline was observed only a day after. Number of crows at the
study site was in general very low. Unlike pigeons, crows reacted better to raptors, flying
immediately away as soon as the raptors were visible, but this may be also a result of their low
numbers and consequent insecurity, or their previous experience with wild raptors. The results
of the study point to the habituation of pigeons to the presence of raptors. Falconry alone is not
efficient enough for bird control for a longer period of time and should be aided with other
methods of bird control. |
| Abstract (croatian) | Golubovi (Columba livia) i vrane (Corvus spp.) su sve prisutniji u urbanim sredinama.
Obje vrste smatraju se štetočinama. Vrane su izuzetno inteligentne i imaju negativan utjecaj na
brojnost manjih vrsta ptica. Pored toga, vrane i golubovi odgovorni su za oštećenja i
onečišćenja zgrada, spomenika, i sl. Nadalje, zabilježeno je da obje vrste prenose uzročnike
bolesti te stoga predstavljaju problem za javno zdravstvo i okoliš. Cilj ovoga istraživanja bio
je analizirati učinak upotrebe treniranih ptica grabljivica na urbane vrane i golubove. Studija je
provedena u tvornici Valipile u Dumovcu, Zagrebačka županija, Hrvatska. Istraživanje je
podijeljeno u tri faze. Prva faza bila je praćenje golubova i vrana na tom području bez
prisutnosti grabljivica tijekom osam dana. U drugoj fazi, grabljivice (Harrisovi jastrebovi)
puštene su četiri puta (2 x 2) u različitim intervalima. Razmak između dva leta grabljivice bio
je 5 dana. Treća faza započela je pet dana nakon druge, a uključivala je četiri istjerivanja.
Razmak između prvog i drugog, te trećeg i četvrtog istjerivanja bio je jedan dan, dok je razmak
između drugog i trećeg bio sedam dana. Prisutnost golubova i vrana praćena je neinvazivno
pomoću tri fotozamke: dvije modela Reolink Go Plus i jedne Scout Guard, model Boly BG590-
24mHD. U prvoj fazi uočena je velika brojnost golubova u jutarnjim satima do podneva (od 8
do 13 sati). Golubovi su u listopadu bili brojniji u tvornici, vjerojatno zbog dovoza kukuruza i
pojačane pripreme ptica za zimu. Tijekom druge faze studije, nakon svakog leta jastrebova
primijećen je nagli pad broja golubova, ali su se sljedeći dan vratili u ˝normalnom˝ broju. U
prvom dijelu treće faze jastrebovi su uzrokovali pad broja golubova tijekom dana leta, dok je
u drugom dijelu taj pad uočen samo dan nakon. Broj vrana na mjestu istraživanja općenito je
bio vrlo nizak. Za razliku od golubova, vrane su bolje reagirale na grabljivice te su odmah
odletjele, no to može biti rezultat njihove male brojnosti i posljedične nesigurnosti ili
prethodnog iskustva s divljim grabljivicama. Rezultati istraživanja ukazuju na navikavanje
golubova na prisutnost grabljivica. Samo sokolarenje nije dostatno učinkovito za dugotrajniju
kontrolu brojnosti ptica i potrebno ga je potpomoći drugim metodama kontrole. |
