evening grosbeaks part 2 The stats

male and female evening grosbeaks 

Well as promised I wanted to look at the stats of evening grosbeak numbers  to try and put our banding season into perspective. When I looked back at the Ontario bird banding journals I only had journals dating back about 12 years which lead to to suggest that the marsh was having a provincial record breaking year.  Fortunately I was able to send send out a request to other Ontario banders  and one of them sent me the historical numbers of evening grosbeaks  banded since 1960.  The first thing I would point out in my defense is that the  numbers show that if you go back to 2002 until present day the maximum number of grosbeaks banded  was 115 which made us feel that we were in great shape. We are currently sitting at 141 grosbeaks banded as of March 13th. I felt that we were making a contribution to helping understand what is happening to grosbeaks moving forward and that the potential for some of these grosbeaks to show up at another banding station or indeed being re-trapped by us in subsequent years would be a worthwhile contribution.  Then I looked at the historical numbers and see that the provincial number of banded grosbeak was  3711 back in 1983.  To put that into perspective the total of banded evening grosbeaks  since 2002 adds up to  823!!!  I cannot imagine  what the size of the flocks must have been for banders to  handle that many birds.  I am headed to the Ontario bird banding  annual conference  at bird studies Canada in Port Rowan  in a couple of weeks and I am looking forward to seeing  some of the banders that were actively catching evening grosbeaks  back when they were so plentiful. The sad news as I mentioned in a previous blog is that there numbers have dwindled to the point that they are now a federal species of concern and perhaps makes the chance to get a band on a bird even more significant for the chance to help track the movements of these boisterous brilliant birds. Try and say that five times fast.  I cannot help but think that the possibility that these birds would be in such low numbers would never have occurred to them when they were banding  so many in the 1980's
     A friend of mine is always pointing out that the last big outbreak of spruce bud worms was in the 1970's and 1980's which perfectly coincides with the the high banding totals that you can look up in the table below . Some may feel that we should not be basing our estimates on populations that were at their peak. This does not however  account for  the fact that grosbeaks are extremely nomadic and will migrate searching either for outbreaks of spruce bud worm or perhaps looking for  feeders with their other favourite food sunflower seeds as feeder watchers will attest to.  One of my concerns about the population dynamics is that is seems unlikely that there should be 50 year  gap between cycles of spruce bud worm outbreaks. Clearly resource management has had an impact on these outbreaks. Perhaps aerial spraying and fire suppression influenced these cycles with a clear impact on the cross Canada population of evening grosbeaks. I for one am glad that they have been listed as a species of concern which will result in a management plan with some suggestion about monitoring  the population moving into the future. I asked Kevin Hannah a Canadian Wildlife Service biologists what he thought about the decrease in population and this is what he sent me. 

"In terms of “normal” levels, I think we’re way below any historic population size. According to the data I’ve seen, based on the Breeding Bird Survey, the Evening Grosbeak population has declined by 86% over the 44 year period from 1970-2014. Much of these declines appear to be from eastern Canada. The most often cited reason for these declines is the control of spruce bud worm and the huge reduction in the size and frequency of outbreaks. Other threats include a loss of habitat due to commercial forestry, mortality from collisions (e.g. windows and cars), and habitat loss/modification due to climate change. As with many species, there’s very little evidence of a direct cause and effect relationship between population changes and these perceived threats, so not exactly a slam dunk in terms of the ultimate causes. There has been, albeit small and localized, a recent increase in spruce bud worm activity in Quebec and parts of Ontario. As a result, there seems to have been some bigger winter “pulses” of this species in the past few years. Perhaps this is a sign of the linkage between this species and bud worms, and signs that populations might be slowly improving. "

      It really is interesting that the last two years we have had our best years for  evening grosbeaks at the marsh and in pockets around the northeast. Again my birder friend mentioned that he saw some flocks of evening grosbeaks in the hundreds one flock potentially near  700 not far from Gowganda. I am curious where the the bud worm outbreaks in Quebec where and how close we are to them. 

      One thing I can say for certain is that  Hilliardton marsh researchers are  excited to have evening grosbeaks this year in the numbers that we do and we will do our best to be part of the research of these beautiful winter finches. The more birds we band the greater the chance for a recovery and adding yet another piece in the puzzle. In addition to the feather isotope study we are helping with I did let the Canadian Wildlife Service know that we have a motus tower  that allows us to track birds fitted with a transmitter so perhaps in the future there are more ways the the hilliardton marsh can help monitor the future health of such spectacular birds. If you have any stories about evening grosbeak numbers historical or otherwise I would love to hear from you. Bird is the word!

Species Number	Species Name	Country or State/Province	Year	Bandings Count	Encounters Count
5140	Evening Grosbeak	Ontario	1960	2,379	133
			1961	375	110
			1962	590	31
			1963	195	25
			1964	435	27
			1965	240	22
			1966	344	27
			1967	0	5
			1968	143	13
			1969	170	15
			1970	13	16
			1971	53	13
			1972	306	14
			1973	46	11
			1974	82	9
			1975	1,019	25
			1976	297	16
			1977	1,647	17
			1978	1,515	19
			1979	1,921	29
			1980	2,175	14
			1981	845	11
			1982	760	9
			1983	3,711	28
			1984	909	12
			1985	1,916	10
			1986	626	1
			1987	531	2
			1988	486	7
			1989	159	2
			1990	539	6
			1991	199	3
			1992	222	2
			1993	215	0
			1994	296	4
			1995	788	2
			1996	279	2
			1997	173	1
			1998	105	1
			1999	79	1
			2000	149	0
			2001	349	0
			2002	80	0
			2003	108	0
			2004	70	0
			2005	54	0
			2006	25	0
			2007	49	1
			2008	20	0
			2009	2	0
			2010	115	0
			2011	56	0
			2012	96	0
			2013	17	0
			2014	14	0
			2015	33	0
			2016	84	0
Totals:				28,104	696