Cooperative harassment strategy by the European Starling to usurp cavities and reproductive cost for the neotropical Green-barred Woodpecker

Figures & data

Table 1. Nest monitoring of a breeding pair of Green-barred Woodpecker (Colaptes melanochloros) in an urban area of La Plata, Argentina, during the 2021–2022 breeding season. Dates of the beginning of nest construction and egg laying are indicated and the type of interaction with the European Starling (Sturnus vulgaris) is detailed.

# Nest	Initiation of cavity excavation	Initiation of egg laying	# Times starling perched near the nest*	# Times groupal harassment was detected	Timing of nest failure	Usurpation by starling	# Starling successful nests
1	4/9/2021	-	2	1	Construction	Yes	2
2	11/9/2021	-	2.5	-	Construction	Yes	1
3	22/9/2021	27/9/2021	1	1	Egg laying	Yes	1
4	1/10/2021	-	1	-	Construction	Yes	-
5	7/10/2021	12/10/2021	1.5	1	Egg laying	Yes	-
6	16/10/2021	23/10/2021	1	-	Nestlings	No	-
7	6/12/2021	10/12/2021	-	-	Nestlings	No	-

*Average number of events per visit (90 min)

Table 2. Features of the nest tree-support of a breeding pair of Green-barred Woodpecker (Colaptes melanochloros) in a urban area of La Plata, Argentina, during the 2021–2022 breeding season.

# Nest	Tree species	Diameter at breast height (cm)	Total tree height (m)	Cavity entrance height (m)	Alive tree	Main stem	Orientation (°)
1	Populus sp.	58	16.5	9.5	Yes	No	10
2	Populus sp.	70	18	7.5	Yes	No	340
3	Populus sp.	58	16.5	8	Yes	Yes	245
4	Populus sp.	53	5.5	5	No	Yes	85
5	Populus sp.	56	17.5	6.5	Yes	No	20
6	Populus sp.	62	16	8.5	Yes	No	320
7	Populus sp.	73	20.5	15.5	Yes	No	290

Figure 1. Image of the Green-barred Woodpecker (Colaptes melanochloros) nest entrance with a European Starling (Sturnus vulgaris) perched near the entrance hole.

Figure 2. Scheme representing the groupal harassment by European Starlings. a), b) and c) show three instances of alternance between starling individuals hovering near a cavity entrance protected by a Green-barred woodpecker. Starling individuals are identified across the sequence by numbers 1–4.