Seasonal benefits of farmland pond management for birds

Figures & data

Table 1. Bird species richness and abundance for seasonal bird α-diversity by pond management type and seasonal γ-diversity of birds over all ponds.

Season	Pond category	Species richness (mean ± se)	Abundance (mean ± se)	Shannon Diversity (exp)	Simpson’s Diversity (1/D)
Breeding	Alpha diversity
	Managed	24.75 ± 1.03***	100.38 ± 7.43***	16.69 ± 0.78***	13.11 ± 0.62***
	Unmanaged	11.75 ± 1.26***	46.50 ± 6.92***	8.25 ± 0.89***	6.82 ± 0.73***
	Gamma diversity
	All Ponds	52	1459	21.96	15.99
	Combined managed	48	992	24.80	18.80
	Combined unmanaged	25	467	12.58	9.74
Post-breeding	Alpha diversity
	Managed	29.2 ± 1.0***	74.25 ± 6.16**	17.80 ± 1.41***	13.05 ± 1.46**
	Unmanaged	12.63 ± 1.0***	41.25 ± 6.05**	8.21 ± 0.66***	6.70 ± 0.60**
	Gamma diversity
	All Ponds	57	1165	23.86	16.90
	Combined managed	52	762	24.96	16.22
	Combined unmanaged	26	403	12.64	9.60
Winter	Alpha diversity
	Managed	17 ± 0.94***	49.25 ± 3.96*	11.30 ± 0.93***	8.82 ± 1.00**
	Unmanaged	9 ± 1.27***	27.88 ± 6.00*	5.83 ± 0.71***	4.63 ± 0.62**
	Gamma diversity
	All Ponds	41	886	17.67	12.00
	Combined managed	39	580	20.04	14.79
	Combined unmanaged	24	306	9.36	6.10

α-diversity represented by mean values ± standard error of the mean. Statistically significant differences between managed and unmanaged ponds are denoted by P < 0.001 (***), P < 0.01 (**) and P < 0.05 (*).

Figure 1. Effect size plots for bird abundance over (a) breeding (b), post-breeding and (c) winter seasons. Taken from GLMM analysis, with se and upper and lower confidence intervals. Significance values as: P < 0.001 ***, P < 0.001 **, P < 0.05 *.

Table 2. Summary of the GLMMs explaining (a) breeding abundance and (b) species richness, in relation to pond features.

Component models	df	logLiK	AICc	delta	weight
Breeding abundance
1, 2, 3, 4	8	−559.97	1136.45	0	0.52
1, 2, 3, 4, 5	9	−559.62	1137.89	1.44	0.25
1, 2, 3, 4, 6	9	559.75	1138.15	1.70	0.22
Species richness
2, 3, 4	7	−695.47	1405.34	0	0.31
1, 2, 3, 4	8	−694.65	1405.81	0.47	0.25
2, 3, 4, 5	8	−695.05	1406.62	1.28	0.17
2, 3, 5	7	−696.28	1406.97	1.63	0.14
2, 3	6	−697.39	1407.09	1.75	0.13

Feature codes: 1: Bramble area, 2: Connectivity, 3: Management, 4: Margin area, 5: Tree area, 6: Water area.

Table 3. Full average parameter estimates from the GLMMs for bird abundance, by season.

	estimate	se	Z	P
Breeding
(Intercept)	1.524	0.085	17.873
Bramble area	0.164	0.050	3.249	**
Connectivity	0.180	0.057	3.144	**
Management	0.470	0.136	3.452	***
Margin area	0.125	0.048	2.602	**
Tree area	0.013	0.038	0.346
Water area	0.007	0.028	0.269
Post-breeding
(Intercept)	0.925	0.135	6.827
Bramble area	0.204	0.082	2.476	*
Connectivity	0.213	0.075	2.817	**
Management	0.271	0.202	1.338
Water area	−0.021	0.051	0.421
Tree area	0.011	0.040	0.278
Winter
(Intercept)	0.256	0.133	1.918
Connectivity	0.480	0.108	4.440	***
Management	0.684	0.179	3.807	***
Tree area	0.197	0.095	2.062	*
Margin area	0.021	0.057	0.373
Water area	−0.014	0.049	0.278

Statistical significance is based on a P-value threshold as P < 0.05 and are denoted by P < 0.001 (***), P < 0.01 (**) and P < 0.05 (*).

Figure 2. Effect size plots for bird species richness (a) over breeding (b), post-breeding and (b) winter seasons. Taken from GLMM analysis, with se and upper and lower confidence intervals. Significance value codes: P < 0.001 ***, P < 0.001 **, P < 0.05 *.

Table 4. Full average parameter estimates from the GLMMs for bird species richness, by season.

	estimate	se	Z	P
Breeding
(Intercept)	3.153	0.065	48.644
Connectivity	0.127	0.048	2.612	**
Management	0.678	0.103	6.533	***
Margin area	0.062	0.053	1.176
Bramble area	0.015	0.034	0.431
Tree area	0.018	0.040	0.459
Post-breeding
(Intercept)	2.497	0.042	58.844
Connectivity	0.154	0.029	5.287	***
Management	0.893	0.067	13.328	***
Tree area	0.099	0.029	3.394	***
Bramble area	−0.025	0.029	0.860
Water area	−0.010	0.020	0.477
Margin area	−0.001	0.009	0.126
Winter
(Intercept)	2.184	0.082	26.390
Connectivity	0.254	0.064	3.984	***
Management	0.578	0.128	4.515	***
Tree area	0.050	0.064	0.780
Water area	0.034	0.055	0.617
Margin area	0.020	0.042	0.465
Bramble area	−0.002	0.017	0.103

Statistical significance is based on a P-value threshold as P < 0.05 and are denoted by P < 0.001 (***), P < 0.01 (**) and P < 0.05 (*).

Figure 3. (a) Bird abundance by pond management and season, (b) bird species richness by pond management and season, (c) conservation priority (red and amber) bird abundance by pond management and season and (d) abundance of aerial insectivores by pond management and season. Boxplots show median, upper and lower quartiles, with data falling outside Q1–Q3 range plotted as outliers. Statistical significance of Mann–Whitney tests denoted by P < 0.001 ***, P < 0.01 **, P < 0.05 * and ns = not significant.