2002 Fall Banding Report for Rocky Point Bird Observatory

TABLE OF CONTENTS

Rocky Point Bird Observatory is a banding station located at the extreme southern tip of Vancouver Island. It is used to monitor the migration route of passerines (as well as raptors and seabirds to a lesser extent). This is done through banding, recaptures, and visual and auditory observations. The dominant passerines migrating through this area that were banded were Ruby-crowned Kinglets, Pacific-slope Flycatchers, Wilson’s Warblers, Winter Wrens and Song Sparrows.

The purpose of this research was to get an idea of the passerines migrating through the southwestern tip of Vancouver Island. Although scientific in nature, it does not give a complete summary of all bird migration. This research needs to be conducted and monitored over many years in order to get an accurate picture. This is the ninth year in existence. Also, to get an understanding of migration patterns, this data should be shared with other banding stations across North America.

This paper, however, concentrates on this particular station. Banding totals are examined as well as the efficiency of the nets. In particular, the reasons why some nets might be more productive and why banding totals were high this year. It is a summary of certain aspects of the 2002 banding season. For more information on Banding Totals and especially on Estimated Totals and Census figures see the RPBO website.

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METHODS

Research Site

The research was conducted from 20 July- 21 October, 2002. Days lost due to blasting by the Department of National Defence (DND) were from 8 October-11 October. The research site was located in rural Metchosin on the Department of National Defence’s Rocky Point Ammunition Depot, on the southwestern tip of Vancouver Island. The area monitored covered 9 km2. The area covered consisted of open meadows, old growth forest including Douglas and Grand Fir, endangered Garry Oaks and riparian habitat.

Nets and Equipment

There were thirteen mist nets in all, five of which were in the open meadow area and the remaining eight in the forest. The type of mist nets used were 70 denier/2-ply, 2.6 x 12 meters, made of nylon, with 30 mm mesh and 4 shelves. For banding purposes, banding pliers, rulers for measurements, and standardized scales for weighing were used. Birds, once caught in nets, were extracted and placed in cotton bags.

Standardized Procedure

Banding, recapture data, census and estimated totals were done daily, weather permitting. Banding and recaptures started with net openings, half an hour before sunrise. Net closing was six hours after net opening. Another hour was permitted to do observations. Therefore, a total of seven hours was spent in the field. Also, one hour after sunrise census was taken. This count area was within the monitoring area, and an individual who could identify birds conducted the count by sight and sound. The census-taker had one hour and twenty minutes to walk the census route and then report all sightings. At the end of each seven-hour day, estimated total (Ets), were tallied. They included all banded birds during the six-hour standardized banding period, the census count and all observations encountered during the seven-hour count period.

Personnel, Duties and Techniques

The research crew consisted of the bander-in-charge, volunteer staff and other volunteers. The bander-in-charge was responsible for banding the birds, teaching and supervising volunteers, opening and closing nets and administering tasks to the volunteers. Banding criteria was based on identifying the species, sex, age, wing chord, fat deposit and weight. This was done with the aid of the official bird-banding guide for North America written by Peter Pyle.

Ageing was done by using a combination of skulling and plumage techniques. Sexing was done using cloacal protrusions (CP) for males and brood patches (BP) for females. Both techniques, however, could only be used on adult birds. Plumage criteria for ageing and sexing could be used on hatch year (HY) and after hatch year (AHY) birds. For more information, see Pyle, 1997.

Where recaptures were concerned, all banding procedures were done with the exception of putting on a band. Volunteers were responsible for extracting birds from nets (after being supervised by the bander-in-charge), census, observations, acting as scribes and maintaining the net lanes. On days of heavy rain and/or high winds the station was not in operation.

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RESULTS

Banding Totals

In total, 3153 individuals were banded including 56 species (Appendix1). The most frequent banded species was the Ruby-crowned Kinglet (466), followed by the Pacific-slope Flycatcher (271) and Wilson's Warbler (231). These three species have been at or near the top for the past nine years of banding at Rocky Point (Table1). They accounted for 30.7% of the total birds banded in 2002. The top ten birds banded accounted for 63.5% of the total.

Banding totals were higher this year compared to the eight previous years (Table2). However, 1995 and 1996 had the highest banded species totals with 62 species recorded. It is important to note that this was the first year that thirteen nets were used on a daily basis. The two highest banding days were 17/09 with 101 and 26/09 with 100 (Appendix2).

Age and Sex

The age and sex of the top ten species banded are tabulated in Tables 3 & 4, respectively. Hatch year birds dominated (1629) compared to 302 after hatch year, one second year and 69 unknown age. Hatch years, therefore, accounted for 81.4% of the total top ten birds. Out of the 2001 top ten birds banded, 1140, or 57.0% were of unknown sex. Winter Wrens and Lincoln’s Sparrows were not sexed at all. Pacific-slope Flycatchers and Song Sparrows were only able to be sexed (all females) on seven occasions (Table4).

Coverage

Banding days accounted for 87 days out of a potential of 94. Four days were lost due to DND blasting near the site and three days were lost due to excessive rain. This comes to 92.6% banding day coverage. Days lost due to rain were 02 September, 16 September and 03 October. Days lost due to DND blasting were 8 October to 11 October.

Since thirteen nets were used daily, net coverage was the highest this year than any other year (Table5). Net hours this year came to 6509.5, out of a potential of 7332 hours if all thirteen nets had been open for the full six hours of the 94-day banding period. Due to weather (wind and/or rain), however, all or some of the nets may have been closed during the six-hour banding period. Also, since banding only occurred on 87 of the 94 potential banding days, each net had a potential of being open for 522 hours during the banding season. Nets1 and 2 were closed the most often. They both accounted for 428 and 428.5 hours respectively. Nets6, 9 and 10 were kept open the most often (517 hours). Table8 gives a detailed account of all the net hours.

The most productive net was net4 with 382 banded followed by net7 with 366 banded birds from that net (Table7). The additional nets (nets11-13) caught 820 of the total birds banded (Table6). This accounts for 26% of the total birds banded. Birds per net hour this year were 0.48 for nets1-13 and 0.53 for nets11-13. Tables 5 & 6 show how they compare to previous years.

Recaptures

In total 608 birds were recaptured. Song Sparrows (98) and Chestnut-backed Chickadee (90) being the most frequent (Table11). Two Wilson’s Warblers banded in 1998 at RPBO were recaptured.

Rarities

There were three new species added to the RPBO sightings list, including Cattle Egret, Marbled Godwit and Rusty Blackbird (Table9). Also, there were two new species added to the RPBO banding list, including Blue-grey Gnatcatcher and Northern Parula (Table10).

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DISCUSSION

Banding Totals

Banding totals were higher this year than previous years in part due to the fact that nets11-13 were open for the entire season. Very high Ruby-crowned Kinglet and Pacific-slope Flycatcher numbers also helped boost banding totals. However, Winter Wren and Orange-crowned Warbler numbers were relatively low compared to previous years. Because of this, it is hard to tell whether numbers were higher for other reasons. Good weather conditions play a certain role. For instance, more birds land when migrating at night when there is a weather disturbance during the night. However, weather conditions this year were very good. It was a very dry season, which could mean that large numbers of birds did not land. Only three full days were lost due to rain. Good breeding years for certain key species such as Ruby-crowned Kinglets and Pacific-slope Flycatchers could increase numbers but this type of insight would need co-operation with other biologists.

Banding totals increased from mid-September onward. This can be misleading, however, when looking at peak migration patterns. Certain species peak at different times. For example, Ruby-crowned Kinglets were banded late in the season from late September to late October. They definitely helped increase banding totals late in the season. Wilson Warblers and Pacific-slope Flycatchers were caught mostly in August and early September. These latter species are known to breed in the area so breeding birds could have helped increase banding totals. Ruby-crowned Kinglets are not known to breed in the immediate area but when they come through late in the season they often constitute most of the birds banded on any given day. Without Ruby-crowned Kinglets, banding in October would be very slow.

Net Coverage

Good coverage can be misleading. While nets hours were extremely high this year compared to previous years, birds per net/hour were not. If there are not as many birds in the area, leaving more nets open will not necessarily mean a higher proportion of birds. It seems that since birds/net hour were low this year, that weather could have played a factor in the total birds caught. In 2001,for instance, if there were thirteen nets open for the full season numbers could have been higher than 2002 due to the fact that birds/net hour were considerably higher. Nets11-13 also were not as efficient as 2001 and 2000. Birds/net hour were considerably higher in both previous years. This could suggest that other factors (other than the total of nets) are involved in total birds banded. The right weather conditions for birds to descend and productive breeding success being two possible considerations. Keeping thirteen nets open for the entire season in the years to come will give a better indication of banding totals.

Some nets were more productive than others. For instance, net8 was very poor. Nets4 and 7 were relatively productive. It could be that the latter nets were more hidden or that the vegetation contained more insects for forage. Nets that are well hidden usually catch more birds and it seems that in this case it was true. Although there were a lot of birds in the vicinity of net8 it was not very well hidden. Nets1 and 2 were very close to nets3 and 4 but not as productive. The previous were in the grassland area. The latter, however, were surrounded by tall bushes and trees as well as grassland. This could suggest that not only are the nets more hidden but also the area may contain a higher diversity of bird species. This seemed to be the case as nets3 and 4 caught high numbers of Sparrows and Warblers while nets1 and 2 caught mostly Sparrows and Goldfinches. Nets1 and 2, however, were often closed due to high westerly winds. This would have a negative impact on their banded totals.

Nets surrounded by a higher diversity of plants might enable birds to find more to forage on (insects, berries and seeds), hide from predators as well as not see nets since the vegetation makes the nets less visible. Various heights of vegetation around nets should also catch birds that forage at different levels. MacArthur (1958) found that five Warbler species occupied feeding niches in firs and spruces that were considerably distinct. Birds that occupy different foraging niches might get caught in different panels thereby increasing the number of birds that get caught. The fact that there is high vegetation surrounding nets and that the nets are well hidden does not in itself mean that they will be productive. Nets5 and 10 were well hidden by tall vegetation but did not catch a significantly higher amount of birds. Birds around these nets such Chestnut-backed Chickadees would often fly over. However, net10 was productive at catching Winter Wrens since they move about at low levels in dense brush.

Sex and Age

Most birds that were caught turned out to be hatch year birds. Skulling in the fall is a big help in determining their age. Pacific-slope Flycatchers were not reliably aged, as their skulls did not always match their plumage criteria. For instance, a bird that was skulled as a hatch year did not necessarily have plumage that would indicate a hatch year especially early in the season. Later in the season, hatch year skulls did match hatch year plumage on a more regular basis.

Species that do not show sexual dimorphism cannot be reliably sexed. These include the Sparrows, Flycatchers and Wrens. Since breeding birds were caught, some adults could be sexed by brood patch or cloacal protrusion. These were limited to breeding birds early in the season. Pacific-slope Flycatcher and Song Sparrows were two such species that were suspected of breeding in the area and were sexed using these methods.

Recaptures

Song Sparrows are suspected of breeding in the area. To confirm this some adults had been found with brood patches. This might help explain their high recapture rate. Wilson’s Warblers and Common Yellowthroats are also suspected breeders. Some hatch years that were caught had barely reached the fledgling stage. The two Wilson’s Warblers caught in 1998 could also help confirm breeding status. Backed-backed Chickadees might use the area to breed and forage year round. Ruby-crowned Kinglets were so numerous this year that recaptures seemed inevitable.

Rarities

Two new species banded this year at RPBO were the Blue-grey Gnatcatcher and the Northern Parula. The previous breeds historically as far north as southern Oregon (National Geographic, third edition). The latter’s breeding range extends as far west as eastern Manitoba (National Geographic, third edition). They were definitely out of their historical range. The Marbled Godwit was seen early in the season on the mudflats and it hung around for several days. The Cattle Egret was a flyover.

Summary

Excellent coverage and additional nets made this the most productive banding season yet. However, because of the lack of weather disturbances it was not the most efficient in terms of birds caught per net. Banding totals should increase in the years to come with thirteen nets open and improved weather conditions. Ruby-crowned Kinglets were exceptionally high this year. Pacific-slope Flycatchers and Wilson’s Warblers were a distant second.

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ACKNOWLEDGMENTS

I wish to thank the following volunteers for their contribution to the banding season:

Gabriel David, June Pretzer, Robert Hadley, Michael Dyson, Ed Pellizzon, Jen Rock, Ted Ardley, Jeremy Gatton, Jessica Murray, Laurie Savard, Erin Burrell, Nathan Debruin, Rob Gowan, Camela Smith, Naira Johnstone, Kim West, Christy Morrissey, Nathan West, Brent Beach, Sue Ennis, Ann Duncan, Michael Clinchy, Joanne MacDonald, John Cooper, Susanne Maidment, Al Storey, Andy Stewart, Claudia Steinacker, Cyril Schonbachler, David Kelly, Kristi Millner, Ginette Heppelle, Rick Toochin, George Clulow, Brian Self, Carlo Giavanello, Owain Mckibbin, Rene Mckibbin, Chris Sanders, Don Eastman, Guy Monty, Eric Higgs, Andrew MacDonald and Dale Jensen.

I would especially like to thank the volunteer staff who run the banding station year-round. Without their tireless support, on and off the field, the season would have been a lot more gruelling. They are as follows:

President… David Allinson

Vice-President… Colleen O’Brien

Treasurer… Thomas Gillespie

Secretary… Denise Gubersky

Rod Mitchell

Ann Nightingale

Paul Levesque

Rick Schortinghuis

Michael Porter

Suzanne Beauschesne

Marilyn Lambert

Lastly, I would like to Jukka Jantunen who was the bander-in-charge for the last ten days of banding.

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LITERATURE CITED

Derbyshire, D. 2000. A report on Migration Monitoring at Rocky Point: Fall 2000. Rocky Point Bird Observatory, Metchosin, British Columbia.

Gibson, G.C. 2001. A report on Migration Monitoring at Rocky Point: Fall 2001. Rocky Point Bird Observatory, Metchosin, British Columbia.

Pyle, P. 1997. Identification Guide to North American Birds. Part1. Slate Creek Press, Bolinas, California.

REFERENCES

MacArthur, R.H. (1958). Population ecology of some warblers of northeastern coniferous forests. Ecology 39. 599-619.

National Geographic. 1999. Field Guide to the Birds of North America. Third Edition. Published by National Geographic Society.

TABLES

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Table 1. Top ten species banded in 2002 compared to years 1994-2001.
Species	2002	2001	2000	1999	1998	1997	1996	1995	1994
Pacific-sloped Flycatcher	271	187	228	228	209	91	54	79	52
Winter Wren	177	204	265	61	135	102	106	64	75
Golden-crowned Kinglet	117	94	81	57	53	37	25	10	26
Ruby-crowned Kinglet	466	186	295	199	156	159	232	79	70
Orange-crowned Warbler	150	220	125	185	117	109	82	67	66
Yellow Warbler	114	109	139	106	57	101	38	45	44
Wilson's Warbler	231	225	177	257	153	53	37	58	70
Song Sparrow	168	109	120	71	101	114	63	79	134
Lincoln's Sparrow	148	102	171	154	160	138	120	124	151
American Goldfinch	159	146	45	68	107	46	39	42	90
Totals	2001	1582	1646	1386	1248	950	796	647	778
Table 2. Total birds banded and species totals from 1994-2002
	2002	2001	2000	1999	1998	1997	1996	1995	1994
Total banded	3153	2576	2723	2255	2127	1818	1571	1260	1547
Total species	56	54	57	61	59	52	62	62	60
*2002 total of 13 nets
*2000-2001 nets 11-13 used only on odd days
*1994-1999 total of 10 nets

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Table 3. The ages of the top ten species banded.
Species	HY	AHY	U	SY
Pacific-slope Flycatcher	212	43	16
Winter Wren	143	27	7
Golden-crowned Kinglet	99	15	3
Ruby-crowned Kinglet	385	55	26
Orange-Crowned Warbler	101	44	5
Yellow Warbler	80	34
Wilson's Warbler	213	12	6
Song Sparrow	149	16	3
Lincoln's Sparrow	122	24	2
American Goldfinch	125	32	1	1
Total	1629	302	69	1
Table 4. The sexes of the top ten species banded.
Species	M	F	U
Pacific-slope Flycatcher		5	266
Winter Wren			177
Golden-crowned Kinglet	64	22	31
Ruby-crowned Kinglet	178	81	207
Orange-crowned Warbler	43	45	62
Yellow Warbler	43	38	33
Wilson's Warbler	116	88	27
Song Sparrow		2	166
Lincoln's Sparrow			148
American Goldfinch	86	50	23
Total	530	331	1140

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Table 5. Coverage effort from 1999-2002.
Year	Coverage period	Days	Banded	Net hours	Birds/net hour
2002	20/07-21/10	87	3153	6509.5	0.48
2001	23/07-7/10	75	2576	4296	0.6
2000	21/07-21/10	90	2724	5113	0.53
1999	23/07-23/10	87	2255	4493	0.48
*1999 ten mist nets used
*2000-2001 ten mist nets and three additional mist nets used on odd days
*2002 thirteen mist nets used
Table 6. Capture rate for nets 11-13 (additional nets).
Year	Banded	Net hours	Birds/net hour
2002	820	1536.5	0.53
2001	394	560	0.7
2000	620	692	0.89
Table 7. Productivity of all thirteen nets.				Table 8. Net hours per net
Net	Banded	% of total		Net	Hours
1	160	5.1		1	428.5
2	225	7.1		2	428
3	354	11.2		3	513.5
4	382	12.1		4	513.5
5	115	3.6		5	516.5
6	204	6.5		6	517
7	366	11.6		7	511
8	60	1.9		8	511
9	288	9.2		9	517
10	173	5.5		10	517
11	295	9.4		11	506.5
12	219	7		12	515
13	306	9.7		13	515
Total	3147	99.9		Total	6509.5
*percentage based on 3147 banded

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Table 9. Non-banded Rarities		Table 10. Banded Rarities
Yellow-billed loon		Northern Pygmy Owl
Sooty Shearwater		Dusky Flycatcher
Fork-tailed Storm Petrel		Blue-gray Gnatcatcher (RPBO first)
Cattle Egret (RPBO first)		Northern Parula (RPBO first)
Broad-winged Hawk		Black-headed Grosbeak
Rough-legged Hawk		Swamp Sparrow
Golden Eagle		White-throated Sparrow
Whimbrel
Marbled Godwit (RPBO first)
Ruddy Turnstone
Red Knot
Pomarine Jaeger
Parasitic Jaeger
Franklin's Gull
Little Gull
Black-legged Kittiwake
Tufted Puffin
Barn Owl
Black Swift
Red-breasted Sapsucker
Lewis's Woodpecker
Bank Swallow
Nashville Warbler
Northern Waterthrush
Western Palm Warbler
Yellow-headed Blackbird
Rusty Blackbird (new RPBO sp.)
Table 11. Top 5 recaptured species.
Species	#
Chestnut-backed Chickadee	90
Ruby-crowned Kinglet	54
Common Yellowthroat	55
Wilson's Warbler	50
Song Sparrow	98

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Appendix 1 Total birds banded
Species	Numbers banded
Sharp-shinned Hawk	10
Northern Pygmy Owl	1
Northern Saw-whet Owl	1
Downy Woodpecker	1
Red-shafted Flicker	2
Traill's Flycatcher	47
Hammond's Flycatcher	23
Dusky Flycatcher	1
Pacific-sloped Flycatcher	271
Hutton's Vireo	4
Warbling Vireo	11
Steller's Jay	8
Violet-green Swallow	4
Northern Rough-winged Swallow	2
Chestnut-backed Chickadee	93
Bushtit	45
Red-breasted Nuthatch	4
Brown Creeper	9
Bewick's Wren	34
House Wren	11
Winter Wren	177
Marsh Wren	8
Golden-crowned Kinglet	117
Ruby-crowned Kinglet	466
Blue-gray Gnatcatcher	1
Swainson's Thrush	62
Hermit Thrush	53
American Robin	15
Cedar Waxwing	7
Orange-crowned Warbler	150
Northern Parula	1
Yellow Warbler	114
Yellow-rumped Warbler	31
Black-throated Grey Warbler	4
Townsend's Warbler	2
MacGillivray's Warbler	48
Common Yellowthroat	74
Wilson's Warbler	231
Black-headed Grosbeak	1
Spotted Towhee	88
Chipping Sparrow	14
Savannah's Sparrow	74
Fox Sparrow	95
Song Sparrow	168
Lincoln's Sparrow	148
Swamp Sparrow	1
White-throated Sparrow	1
White-crowned Sparrow	96
Golden-crowned Sparrow	66
Oregon Junco	63
Red-winged Blackbird	8
Brown-headed Cowbird	7
Purple Finch	6
House Finch	6
Pine Siskin	9
American Goldfinch	159
Total individuals	3153
Total Species	56

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Appendix 2 Captures per day.
Date	Banded
20-Jul	28	31-Aug	17	19-Oct	17
21-Jul	29	1-Sep	7	20-Oct	14
22-Jul	31	3-Sep	32	21-Oct	18
23-Jul	37	4-Sep	23	Total banded=3156
24-Jul	38	5-Sep	51	Total days banding=87
25-Jul	24	6-Sep	61	Average/day=36
26-Jul	45	7-Sep	67
27-Jul	27	8-Sep	17
28-Jul	27	9-Sep	11
29-Jul	11	10-Sep	8
30-Jul	33	11-Sep	59
31-Jul	31	12-Sep	37
1-Aug	48	13-Sep	27
2-Aug	30	14-Sep	20
3-Aug	35	15-Sep	16
4-Aug	21	17-Sep	101
5-Aug	27	18-Sep	80
6-Aug	57	19-Sep	26
7-Aug	36	20-Sep	50
8-Aug	26	21-Sep	50
9-Aug	22	22-Sep	39
10-Aug	25	23-Sep	54
11-Aug	20	24-Sep	51
12-Aug	24	25-Sep	44
13-Aug	8	26-Sep	100
14-Aug	14	27-Sep	58
15-Aug	11	28-Sep	60
16-Aug	14	29-Sep	74
17-Aug	14	30-Sep	66
18-Aug	26	1-Oct	70
19-Aug	19	2-Oct	66
20-Aug	50	4-Oct	85
21-Aug	33	5-Oct	69
22-Aug	38	6-Oct	44
23-Aug	24	7-Oct	40
24-Aug	39	12-Oct	37
25-Aug	30	13-Oct	24
26-Aug	17	14-Oct	26
27-Aug	33	15-Oct	28
28-Aug	17	16-Oct	29
29-Aug	27	17-Oct	48
30-Aug	46	18-Oct	40

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