Table 1. Parameter values used in the model, with symbols, units and references.

Parameter	Symbol	Unit	Value	Reference
On pondweed beds (tuber foraging)
Water level pursued by water manager		m	-0.93**	a
Minimum water depth suitable for foraging		m	0.10	b
Maximum water depth for head-dipping		m	0.51	[32]
Maximum reachable depth		m	0.86	[27]
Tuber burial depth shape factor	β(Sand)	-	0.00077	[32]
	β (Clay)	-	0.00090	[32]
Energy density of food	e	J g-1	16866	[34]
Proportion of time spent foraging	f	-	0.66	[35]
Proportion of foraging time spent underwater	φ(Sand)	-	0.76	[32]
	φ(Clay)	-	0.72	[32]
Attack rate	a(Sand)	m2 s-1	0.00102	[34]
	a(Clay)	m2 s-1	0.000612	[32]
Handling time	h	s g-1	1.82	[34]
Benefit from area-restricted search	b	-	1.38	[36]
Assimilation efficiency	q	-	0.9	[34]
Metabolic rate while foraging	cf (S-S*)	J s-1	45.1	[27]
	cf (S-D*)	J s-1	56.7	[27]
	cf (C-S*)	J s-1	58.6	[32]
	cf (C-D*)	J s-1	73.7	[32]
Metabolic rate while resting	cr	J s-1	22.2	[34]
Metabolic rate while preening	cp	J s-1	33.8	[34]
Metabolic rate while flying		J s-1	204	[37]
Flight speed		m s-1	12.8	[34]
Mean flight distance (between inlets)		m	3317	c
Mean costs per flight (between inlets)		J	52699	c
Lean body mass		g	4660	[38]
Energy density of stores		J g-1	27.5 103	[39]
Initial energy store of swans		J	14.3 106	[40, 41]
Target energy store of swans		J	49.0 106	[40, 41]
On fields (sugar beet foraging)
Fraction of pondweed gain at switch to fields	p	-	0.65	[34]
Daily metabolizable energy intake	MEIb	J day-1	7.50 106	[34]
Daily energy expenditure	DEEb	J day-1	2.61 106	[34]

*S-S: sandy-shallow; S-D: sandy-deep; C-S: clayey-shallow; C-D: clayey-deep;

**above sea level (Normaal Amsterdam’s Peil, NAP).

References: a: Waterschap Noorderzijlvest; b: Personal observations; c: This study.