ISSN 1067-4136, Russian Journal of Ecology, 2016, Vol. 47, No. 2, pp. 200–206. © Pleiades Publishing, Ltd., 2016.
Do Forest Birds Take the Risk of Feeding in an Open Area in Winter?
Experiment with Extra Food Gradually Moved Away from the Edge
of the Forest Into the Open Area
and Jacek Zieliński
Department of Vertebrate Zoology, Faculty of Biology and Environmental Protection, Nicolaus Copernicus University,
Lwowska 1, 87-100 Toruń, Poland
Department of Zoology and Landscaping, UTP University of Science and Technology,
Kordeckiego 20, 85-225 Bydgoszcz, Poland
e-mail: email@example.com; firstname.lastname@example.org
Received September 30, 2015
Abstract—This paper attempts to determine whether and to what extent forest birds take the risk of feeding in
an open area in winter. In each of three plots the extra food (lard) was initially placed on the border of the
forest and open area and then moved into the open area and located within 15, 30 and 45 m from the edge of
the forest. Only in one plot the total number of all the birds feeding on lard significantly decreased along with
the food being moved away from the edge of the forest. In other plot the number of the most numerous Great
Tit Parus major and Blue Tit Cyanistes caeruleus significantly increased along with the food source being
moved away into open area. The numbers of the other 7 species of birds fell or did not have directional nature.
Only in one plot the aggregation (the number of individuals of a given species feeding simultaneously)
increased significantly along with moving the food into open area. In other plots differences in aggregation
did not have the directional nature and, in most cases, were not significant.
Keywords: winter avifauna, extra food, aggregation, Parus, foraging behavior
Previous studies indicate that small birds living in
forest ecosystems tend to avoid staying in open area
(Desrochers and Hannon, 1997; Desrochers and For-
tin, 2000; Bélisle and Desrochers, 2002; Creegan and
Osborne, 2005). Bélisle and Desrochers (2002)
showed that the birds do not choose the shortest path
to their destination if they have to fly through an open
space, but mostly bypass the open area and fly an indi-
rect route through the forest.
Avoiding open areas by forest birds is associated
with an increased danger of being depredated (Des-
rochers and Hannon, 1997; Rodríguez et al., 2001;
Bélisle and Desrochers, 2002; Turcotte and Des-
rochers, 2003; Creegan and Osborne, 2005). Dense
vegetation of trees and shrubs creates—especially for
small birds—greater opportunities to hide from preda-
tor attack and to be in places that are hard to reach for
bigger and less manoeuvrable bird predators (Kull-
Previous studies focused primarily on the descrip-
tion of the behaviour of the birds, which must decide
to fly through an open area between two forest areas
(e.g.: Bélisle and Desrochers, 2002; Norris and
Stutchbury, 2002; St Clair, 2003; Creegan and
Osborne, 2005; Boscolo et al., 2008; Robertson and
Radford, 2009). A measurable benefit for the birds,
despite the risk of being caught by a predator, is mini-
mizing energy expenditure by shortening the route to
the destination. An open area may be attractive for for-
est birds also, because of the food. This happens espe-
cially in winter, when the amount and distribution of
food play a key role in the survival of the birds, and
there are less and less dispersed and non-renewable
food resources, (Jansson et al., 1981; Hogstad, 1989;
Stapanian et al., 1999; Jokimäki et al., 2002; Turcotte
and Desrochers, 2003). Pulido and Díaz (2000) indi-
cate how attractive extra food can be for tits in winter.
These authors report that during the winter food
resources are 2.5 times lower, while energy demands of
tits are twice as large compared to the spring.
This paper attempts, for the first time in ornitho-
logical studies, to determine whether and to what
extent forest birds take the risk of feeding in winter on
extra food placed in an open area. We assumed that
decisions made by the birds, resulting from ambivalent
drives (motivations) of the fear of a predator, as well as
the desire to obtain food, will differ depending on the
species and distance of food from the forest edge.
The article is published in the original.